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1.
Summary The effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) (2.3×10-12-1.4×10-6 [M]) on alkaline phosphatase, collagen, and cell proliferation were examined in primary cultured hypertrophic chondrocytes prepared from the distal epiphyseal growth plate of the tibias of 12-day chick embryos. 1,25(OH)2D3 showed time- and dose-dependent inhibitory effects on the alkaline phosphatase and collagen levels. The inhibition of alkaline phosphatase activity became detectable at 2×10-11 [M] and reached 10% of control at 10-7 [M]. The concentration of 1,25(OH)2D3 giving a 50% inhibition of the enzyme level was approximately 3×10-10 [M]. Of the two extracellular collagen pools, a cell-associated matrix pool showed a more dramatic decrease (to 10% of control) than a culture medium pool (to 50% of control) at increased 1,25(OH)2D3 concentrations. The degree of inhibition was different for each type of chondrocyte-specific collagen (types II, IX, X, and XI). Types II and IX were inhibited in a parallel manner to only 60–80% of control. On the other hand, types X and XI were more greatly reduced up to 10% of control, and their dose-dependent inhibitory curves were similar to that of alkaline phosphatase. On cell proliferation, 1,25(OH)2D3 had a biphasic effect: stimulation at 10-10–10-8 [M] and inhibition at higher levels. The results revealed the significant involvement of 1,25(OH)2D3 in the metabolism of two probable calcification-related products, alkaline phosphatase and type X collagen. 相似文献
2.
Summary To determine the relationship between alkaline phosphatase (AP), 1,25(OD)2D3 and bone formationin vivo, we have examined the effects of levamisole, a stereospecific inhibitor of AP on bone formation and on 1,25(OH)2D3-stimulated bone mineralization in the mouse. Normal mice were injected daily with levamisole at doses of 40 and 80 mg/kg/b.w.
The compound was given alone or in combination with 1,25(OH)2D3 infusion (0.05 μg/kg/d) for 7 days. Treatment with levamisole alone inhibited the serum AP activity (mainly of skeletal origin
in mice) by 18.4 and 61.3% for the low and high dose respectively. No deleterious effect on body growth, tibia length, and
bone cells population was detected. The moderate inhibition of AP activity produced by the lower dose of levamisole alone
(18.4%) or in combination with 1,25(OH)2D3 (37.9%) was associated with a reduced endosteal matrix apposition rate (MaAR) determined by double3H-proline labeling method. This effect was related to a levamisole-induced fall in serum phosphate. Despite the moderate inhibition
of AP activity, the mineral apposition rate (MiAR) determined by the double tetracycline labeling method remained normal.
Moreover, 1,25(OH)2D3 infusion still resulted in increased MiAR which was stimulated to the same extent as in the absence of levamisole. By contrast,
the more severe inhibition of AP activity induced by 80 mg/kg of levamisole alone (61.3%) or in combination with 1,25(OH)2D3 (45.8%) inhibited both the MaAR and the MiAR and prevented the stimulatory effect of 1,25(OH)2D3 on bone mineralization. The data show that AP activity affects the bone matrix and mineral apposition ratesin vivo and that severe inhibition of AP activity inhibits the 1,25(OH)2D3-induced stimulation of bone mineralization in the mouse. 相似文献
3.
Summary Cultured mouse kidney cells grown in serum-free medium were used to assess the metabolism of 25-hydroxyvitamin D3 in the presence of simulated metabolic acidosis. Kidney epithelial cells isolated from 4–6 week old mice were grown to confluence
in a defined serum-free medium at pH 7.4. The confluent monolayers were incubated with tritiated 25-hydroxyvitamin D3 for 6 hours, the samples were extracted, and vitamin D metabolites were separated and quantitated by high pressure liquid
chromatography (HPLC). The pH of the incubation medium was set at 6.9, 7.1, 7.4, or 7.7 by adjusting the bicarbonate concentration,
using chloride as the balancing anion at constant Pco2. When pH was altered at the beginning of the 6 hour assay, production of 1,25-dihydroxyvitamin D3 was the same at each pH. More prolonged pH perturbation for a total of 30 hours likewise had no influence on 1,25-dihydroxyvitamin
D3 production. These results confirm that intact mammalian kidney cells in serum-free culture possess an active 25-hydroxyvitamin
D3-1-hydroxylase and that the activity of the enzyme is unaffected by pH over the range 6.8–7.7. In experiments where acidosis
has been shown to alter 1,25-dihydroxyvitamin D3 production, the mechanism was probably indirect. 相似文献
4.
Stavros C. Manolagas Jean Abare Leonard J. Deftos 《Calcified tissue international》1984,36(1):153-157
Summary We have used cultured osteoblastlike rat osteogenic sarcoma cells (ROS 17/2) which have receptors for 1,25(OH)2D3 and for glucocorticoids, and have examined the modulation of the 1,25(OH)2D3 receptor by the potent glucocorticoid triamcinolone acetonide. We report that triamcinolone acetonide caused an increase
of the 1,25(OH)2D3 receptor concentration in these cells but it did not affect the affinity of the receptor to 1,25(OH)2D3; this phenomenon occurred in a dosedependent fashion for triamcinolone (10−9 to 10−7 M) with a maximum increase of 1,25(OH)2D3 receptor concentration of ⋍twofold. During the culture period, the 1,25(OH)2D3 receptor concentration was altered both in untreated as well as in triamcinolone-treated cells, being highest at the early
logarithmic phase and diminished progressively as cells approached confluence. However, throughout the culture period, the
1,25(OH)2D3 receptor concentration was higher in the triamcinolone-treated cells. 相似文献
5.
J. P. T. M. van Leeuwen H. A. P. Pols J. P. Schilte T. J. Visser J. C. Birkenhäger 《Calcified tissue international》1991,49(1):35-42
Summary The effects of epidermal growth factor (EGF) on basal 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) receptor level and on parathyroid hormone (PTH)-induced 1,25-(OH)2D3 (OH)2D3 receptor up-regulation were studied in the phenotypically osteoblastic cell line UMR 106. EGF in concentrations exceeding
0.1 ng/ml reduced the number of 1,25(OH)2D3 binding sites without changing the binding affinity. Maximal reduction was 30% at about 1 ng/ml. This reduction was independent
of a change in cAMP content. EGF dose-dependently attenuated both PTH-induced 1,25(OH)2D3 receptor up-regulation and PTH-stimulated cAMP production without and effect on the ED50 of the PTH effects. For both PTH responses the IC50 and the maximal effective dose were similar, 0.1 ng/ml an 1 ng/ml EGF, respectively. Reduction was first seen at 0.01 ng/ml
EGF. At this concentration. EGF reduced PTH-stimulated 1,25-(OH)2D3 receptor binding without an inhibition of the cAMP response. Time-course studies with 1 ng/ml EGF revealed that at 2 h preincubation
EGF reduced the heterologous up regulation by PTH, and maximal inhibition was seen after 4 h. In contrast, PTH-stimulated
cAMP production was just significantly inhibited only after 6 h, with 60% inhibition after 24 h preincubation. The effects
of prostaglandin E2 and forskolin on both 1,25(OH)2D3 binding and cAMP production were inhibited in a similar fashion. On the other hand, dibutyryl cAMP- and 3-isobutyl-1-methylxanthinestimulated
1,25(OH)2D3 binding were not affected by EGF. Taken together, our results demonstrate that EGF reduces both the basal number of 1,25(OH)2D3 binding sites and the heterologous up-regulation of the 1,25(OH)2D3 receptor. The current data suggest that EGF reduces heterologous upregulation of the 1,25(OH)2D3 receptor independent of as well as dependent on the cAMP messenger system. The EGF effect is not primarily located at the
PTH receptor, at cAMP phosphodiesterase, or at protein kinase A level. 相似文献
6.
Silvano Bertelloni G. I. Baroncelli G. Di Nero G. Saggese 《Calcified tissue international》1992,51(1):20-23
Summary Idiopathic juvenile osteoporosis (IJO) is a rare form of bone demineralization that occurs during childhood. The mechanism of bone loss is unclear. Some bone hystomorphometric studies have found osteoblast failure and decreased bone formation in the affected patients whereas others have reported increased bone resorption. To elucidate this issue, we studied osteoblast function in six patients with IJO (five males, one female; aged 2.3–14.6 years) and five healthy sex- and age-matched subjects (four males, one female; aged 2.0–15.1 years) measuring serum values of osteocalcin under basal condition and during an osteoblast stimulation test performed by oral 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] administration (1.8 g/1.73 m2/daily). After a baseline day (day 0), all the subjects (patients and controls) received 1,25(OH)2D3 in four divided doses for 6 days (days 1–6). Fasting blood samples were obtained every morning (0800 h) for the determination of serum osteocalcin. Baseline osteocalcin levels were not significantly different between IJO and controls (13.58±6.05 ng/ml versus 16.04±5.09 ng/ml, respectively) even if two patients had low osteocalcin values. During 1,25(OH)2D3 administration, serum osteocalcin values significantly increased (P<0.001) from baseline in both children with IJO and controls, reaching peak values not significantly different in the two groups. Our results do not support the hypothesis that defective osteoblast function is the primary factor of bone demineralization in IJO. 相似文献
7.
Y. Seino K. Yamaoka M. Ishida H. Yabuuchi M. Ichikawa H. Ishige H. Yoshino L. V. Avioli 《Calcified tissue international》1982,34(1):265-269
Summary This study presents measurements of serum vitamin D metabolites, calcium and phosphorus as well as measurements of the equilibrium
dissociation constant for duodenal 1,25(OH)2D3 receptor in 15-, 18-, 19-, and 20-day chick embryos in comparison to that in 1- and 118-day-old chicks and to vitamin D-deficient
chicks. The present results showed that: (a) serum 1,25(OH)2D and 24,25(OH)2D levels rise from 15 and 18 to days 19 and 20 of embryonic development while serum phosphate levels are stable; (b) serum
calcium levels rise at hatching to adult levels; (c) the duodenal 1,25(OH)2D3 receptor is detectable in 15-day-old embryo and has a Kd similar to that of 118-day-old vitamin D-replete chicks; and (d)
the activity of 1,25(OH)2D3 receptor in chick duodenal cytosol is maximal at hatching. 相似文献
8.
Yusuke Tsukamoto M.D. 《Journal of bone and mineral metabolism》1991,9(1):54-57
Conclusion In our experience, after a few months of therapy, every patient showed a marked improvement in both X-ray abnormalities derived
from osteitis fibrosa and symptoms of renal osteodystrophy, especially bone pain, unless the serum phosphorus level was very
high. The effectiveness of this therapy on the suppression of PTH secretion apparently depends on the initial PTH level, and
also on the size of the gland itself. One of the major current difficulties in this therapy is the prevention of hypercalcemia
when calcium carbonate is used. The calcium concentration of the dialysate must be reduced to 2.5 mEq/l not only for pulse
therapy, but also for conventional therapy by vitamin D with calcium carbonate. Parathyroidectomy should be indicated only
for the patient who does not respond to pulse therapy. 相似文献
9.
Human promyelocytic HL-60 cells can be induced by biochemical agents to differentiate in vitro towards divergent types of myelomonocytic cells. It has been reported that prostaglandin E1 (PGE1) can induce granulocytic differentiation and that 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) can induce monocytic differentiation. We have now examined the effects of these compounds, both alone and in combination, on HL-60 cell differentiation. PGE1 (1 g/ml) or 1,25(OH)2D3 (10 nM) each inhibited cell proliferation over 48–96 hours of treatment, but combined treatment with both agents was necessary to produce a strong inhibition. The percentage of HL-60 cells that can reduce nitroblue tetrazolium (NBT) (a characteristic index of early monocytic or granulocytic differentiation) increased 13-fold within 72 hours of PGE1 treatment, and 1,25(OH)2D3 produced a fivefold stimulation. However, combined treatment (PGE1 plus 1,25(OH)2D3) produced a dramatic 35-fold increase. HL-60 cells did not produce significant levels of nitric oxide (NO) before 48 hours in culture, and treatment with PGE1 or 1,25(OH)2D3 did not significantly increase cellular NO elaboration over control levels. However, combined treatment produced a striking 12-fold increase over control levels. Similarly, combined treatment was necessary to obtain the maximal time-dependent stimulation of cellular lactate dehydrogenase (LDH) activity (a marker of granulocytic differentiation) as well as acid phosphatase (ACP) activity. During this same period of time, PGE1, but not 1,25(OH)2D3, markedly stimulated cellular claboration of interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-, and 1,25(OH)2D3 cotreatment strongly augmented these effects. Thus, combined treatment with 1,25(OH)2D3 plus PGE1 generally augmented the apparent conversion of these cells, producing synergistic (multiplicative) or additive effects. Furthermore, PGE1 induced within 48 hours the more general phenotypic changes classically associated with the differentiation of these cells: increased expression of chloroacetate esterase (ChAE) (a granulocytic marker), decreases in the nuclear/cytoplasmic ratio (characteristic of development beyond the promyelocyte/myelocyte stage), and major alterations in morphology from floating spherical cells to loosely adherent, elliptical polygons. 1,25(OH)2D3 had little effect itself on most of these parameters, but augmented the morphological changes induced by PGE1 treatment. Within 48 hours, the ability of these cells to reduce the tetrazolium salt WST-1, a general measure of cellular metabolic activity, was increased by PGE1, but not by 1,25(OH)2D3; however, the combination of 1,25(OH)2D3 and PGE1 again produced the strongest stimulation. Similarly, only PGE1 significantly reduced intracellular ATP levels, but combined treatments produced a more pronounced decrease. In summary, our findings suggest that PGE1, not 1,25(OH)2D3, is sufficient to promote rapid in vitro differentiation of HL-60 cells along the granulocytic pathway; however, the PGE1-induced conversion of these cells is markedly augmented by cotreatment with 1,25(OH)2D3. In addition, these converted HL-60 cells preferentially utilize the glycolytic pathway, rather than the citric acid cycle, for production of ATP, a metabolic characteristic that resembles that described for mature granulocytes. 相似文献
10.
Dr. Ana R. de Boland Virginia Massheimer Luis M. Fernandez 《Calcified tissue international》1988,43(6):370-375
Summary 1,25 Dihydroxyvitamin D3 has been shown to stimulate calcium fluxes across skeletal muscle membranes. The involvement of calmodulin in the effects
of the metabolite was investigated. Primary cultures of chick embryo skeletal muscle myoblasts and soleus muscles from vitamin
D-deficient or 1,25 (OH)2D3-treated chicks were used. Culture of myoblasts and vitamin D-deficient soleus with 1,25 (OH)2D3 (0.05 ng/ml) for 24 and 1 hour, respectively, significantly increased45Ca uptake by the preparations. In the presence of the calmodulin antagonists flufenazine or compound 48/80 in the uptake medium,
no differences between control and treated cultures were observed. The calmodulin content of myoblasts and soleus homogenates
and subcellular fractions derived therefrom was estimated by measuring their capacity to stimulate calmodulin-depleted cAMP
phosphodiesterase. No changes in total calmodulin cellular content could be detected in response to 1,25(OH)2D3. However, the sterol produced an increase in calmodulin levels of microsomes, mitochondria, and crude myofibrillar fraction
and a proportional decrease in cytosolic calmodulin concentration. The 1,25(OH)2D3-dependent changes in calmodulin distribution among subcellular fractions of soleus muscle were observed eitherin vivo orin vitro. The effectsin vitro were already detectable after 5 minutes of treatment with the sterol and parallel 1,25(OH)2D3-dependent changes in tissue Ca uptake. The results suggest that changes in calmodulin intracellular distribution may underly
part of the mechanism by which 1,25(OH)2D3 affects muscle calcium transport. 相似文献
11.
G. G. Langston L. D. Swain Z. Schwartz F. Del Toro R. Gomez Barbara D. Boyan 《Calcified tissue international》1990,47(4):230-236
Summary Vitamin D3 metabolites have been shown to affect proliferation, differentiation, and maturation of cartilage cells. Previous studies
have shown that growth zone chondrocytes respond primarily to 1,25(OH)2D3 whereas resting zone chondrocytes respond primarily to 24,25(OH)2D3. To examine the role of calcium in the mechanism of hormone action, this study examined the effects of the Ca ionophore A23187,
1,25(OH)2D3, and 24,25(OH)2D3 on Ca influx and efflux in growth zone chondrocytes and resting zone chondrocytes derived from the costochondral junction
of 125 g rats. Influex was measured as incorporation of45Ca. Efflux was measured as release of45Ca from prelabeled cultures into fresh media. The pattern of45Ca influx in unstimulated (control) cells over the incubation period was different in the two chondrocyte populations, whereas
the pattern of efflux was comparable. A23187 induced a rapid influx of45Ca in both types of chondrocytes which peaked by 3 minutes and was over by 6 minutes. Influx was greatest in the growth zone
chondrocytes. Addition of 10−8–10−9 M 1,25(OH)2D3 to growth zone chondrocyte cultures results in a dose-dependent increase in45Ca influx after 15 minutes. Efflux was stimulated by these concentrations of hormone throughout the incubation period. Addition
of 10−6–10−7 M 24,25(OH)2D3 to resting zone chondrocytes resulted in an inhibition in ion efflux between 1 and 6 minutes, with no effect on influx during
this period. Efflux returned to control values between 6 and 15 minutes.45Ca influx was inhibited by these concentrations of hormone from 15 to 30 minutes. These studies demonstrate that changes in
Ca influx and efflux are metabolite specific and may be a mechanism by which vitamin D metabolites directly regulated chondrocytes
in culture. 相似文献
12.
13.
Socorro Vargas Roger Bouillon Hugo Van Baelen Dr. Lawrence G. Raisz 《Calcified tissue international》1990,47(3):164-168
Summary Vitamin D and its metabolites are tightly bound to the serum vitamin D-binding protein (DBP) and only the free hormone is
considered to be physiologically active. On the other hand, DBP could interact with cell membranes and even favor its intracellular
entry. The present study was undertaken to examine the effects of DBP on bone resorption stimulated by 1,25-dihydroxyvitamin
D3 [1,25(OH)2D3]. Forelimb bones from 19-day-old fetal rats were cultured for 5 days in the presence of purified human or rat serum albumin
(hSAP or rSAP) and 1,25(OH)2D3, with or without human or rat DBP (hDBP or rDBP). Bone resorption was assessed by measuring the release of previously incorporated45Ca. We found that the resorptive response to 1,25(OH)2D3 was minimally altered by hDBP (5 μM). The minimal effects of hDBP on 1,25(OH)2D3 activity on rat bones might be explained by a 6-fold lower affinity of hDBP (1.1×107 M−1) than rDBP (5.9×107 M−1) for 1,25(OH)2D3 or by species differences in cellular recognition of DBP. In a homologous rat system, however, rDBP at low (0.5 μM) or physiological
(5 μM) concentration significantly decreased 1,25(OH)2D3-induced bone resorption. These data therefore support the hypothesis that free rather than DBP-bound 1,25(OH)2D3 is physiologically important. 相似文献
14.
Summary Rachitic rats, maintained on diets with low or normal P contents, were given daily intraperitoneal doses of 1,25(OH)2D3 or 25OHD3 at levels of 100 or 200 ng. Plasma chemistry was measured and the ash content and histological appearance of the bones investigated.
Using labeled material it was shown that the dosing levels of 1,25(OH)2D3 employed ensured a higher than normal plasma concentration of that metabolite over the period between doses. 1,25(OH)2D3 was not as effective as 25OHD3 in raising bone ash or reducing the amount of osteoid. The difference between the effects of the metabolites was evident
at both dietary P levels, but more marked at the higher P level. In contrast, the metabolites reduced the width of the epiphyseal
plate to an approximately similar degree, and this is possibly the reason why there are discrepancies between previous reports
of the effectiveness of 1,25(OH)2D3 compared with 25OHD3 or vitamin D3. Dosing with 1,25(OH)2D3 failed to maintain a constant plasma Pi value over the period between doses in animals fed the low P diet. 相似文献
15.
Summary The direct effect of 1,25(OH)2D3 upon osteoclast formation from precursor cells is still unknown. In the present experiments we have tested the effects of
1,25(OH)2D3 on the generation of osteoclastlike cells in cat bone marrow cultures. These cultures contain proliferating nonattached mononuclear
cells and precursor cells that subsequently attach to the culture flask surface and then fuse to form multinucleated osteoclastlike
cells. After 7 days of culture we separated the nonattached precursor cells from the attached cells and studied the effects
of 1,25(OH)2D3 (10−10 M–10−8 M) on multinucleated cell formation in these two cell populations. In cultures derived from the non-attached precursor cells,
7 days of treatment with 1,25(OH)2D3 (10−8 M) resulted in a 180% increase in the number of attached mononuclear cells and a 90% increase in the number of nuclei contained
within multinucleated cells. These effects were dose-dependent. 1,25(OH)2D3 did not have a consistent effect on the number of nonattached precursor cells. In cultures derived from attached cells, 7
days of treatment with 1,25(OH)2D3 (10−8 M) induced a 50% increase in the number of mononuclear attached cells and a 40% increase in the number of nuclei within polykaryons.
The most likely explanation for these results is that 1,25(OH)2D3 promotes the differentiation and subsequent adhesion of nonattached precursor cells, stimulates proliferation of attached
mononuclear precursor cells, and possibly stimulates fusion of these attached precursor cells. 相似文献
16.
Dr. M. Gunness-Hey I. Gera J. Fonseca L. G. Raisz J. M. Hock 《Calcified tissue international》1988,43(5):284-288
Summary Parathyroid hormone (PTH) alone is known to increase bone mass, but clinical studies of osteoporotic men suggest that when
1,25 dihydroxyvitamin D3 (1,25(OH)2D3) is given in combination with PTH, the effect on bone growth is enhanced. To determine if 1,25(OH)2D3 alone would stimulate bone growth, young male rats were given daily subcutaneous injections of either vehicle or 2.5, 5,
10, or 20 ng 1,25(OH)2D3 per 100 g body weight for 30 days. To determine if 1,25(OH)2D3 would augment the PTH anabolic response, rats were given daily subcutaneous injections of either vehicle for 12 days; or
4 μg/100 g hPTH alone or in combination with 5 ng/100 g 1,25(OH)2D3; or 8 μg/100 g hPTH alone or in combination with 5 ng/100 g 1,25(OH)2D3. Calcium (Ca), dry weight (DW), and hydroxyproline (Hyp) of the distal femur; the rate of mineralization in the metaphysis
of the proximal tibia; and serum calcium and phosphate were measured. Low normocalcemic doses of 1,25(OH)2D3 did not significantly stimulate bone growth. 1,25(OH)2D3 did not augment the PTH-stimulated anabolic effect in young male rats. Low doses (2.5 and 5 ng) of 1,25(OH)2D3 were not hypercalcemic, and there was no increase in total bone calcium or dry weight although the 5 ng dose increased trabecular
bone calcium. 1,25(OH)2D3 at 10 and 20 ng increased trabecular bone DW and Hyp, but mineralization was impaired and rats were hypercalcemic. 1,25(OH)2D3 in combination with PTH did not augment the PTH stimulation of bone growth as trabecular and cortical bone Ca, DW, and HYP
were not increased in rats given both hPTH and 1,25(OH)2D3 compared with values for rats treated with hPTH alone. 相似文献
17.
We have reported that physiological dose (30pM-650pM) of 1,25-dihydroxyvitamin D3[1,25(OH)2D3] increased the unidirectional movement of45Ca2+ from the lumen to the venous effluent within a few minutes in perfused duodena from normal chicks, and hypercalcemia inhibited
this rapid stimulatory effect on calcium transport mediated by 1,25(OH)2 D3. The purpose of the present study was to determine the effect of somatostatin on calcium transport in chicks. The basal Ca2+ transport, in the absence of 1,25(OH)2 D3, did not change when 10−8M to 10−6M of somatostatin was added to the perfusate. The effect of 1,25(OH)2D3 on calcium transport, however, was completely abolished on addtion of 10−6M somatostatin in the perfusate, and partially blocked on addition of 10−7M somatostatin and 10−8M somatostatin had no effect on 1,25(OH)2 D3 mediated calcium transport. These results suggest that somatostatin may decrease intestinal calcium transport mediated by
the rapid direct action of 1,25(OH)2 D3. 相似文献
18.
Summary The responses of suckling rat pups of different ages to high doses of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) were determined. Four daily oral doses of 1,25(OH)2D3 (2 ng/g body wt) given to 9–13-day-old pups produced severe hypercalcemia 24 h after the last dose (15.52 ± 0.14 mg/dl vs.
10.94 ± 0.15 mg/dl in controls of the same age) and a 9-fold increase in kidney Ca content; the same doses given to 16–20-day-old
pups produced only modest hypercalcemia (12.34 ± 0.22 mg/dl vs. 10.57 ± 0.22 mg/dl in controls of the same age) and a 4-fold
increase in kidney Ca content. There was no change in serum phosphorus (P) at either age. Six-week-old weaned rats, given
the same doses of 1,25(OH)2D3, showed neither hypercalcemia nor kidney calcification and thus were protected against the toxic effects of the treatment.
The difference in responses of the twoages of suckling pups was also observed with lower doses. Removal of the solid food
from the diet of the 16–20-day pups showed that the consumption of solid food, in addition to milk, in this age group was
not the cause of the lower serum Ca response. The changes in both serum and kidney Ca after intraperitoneal (i.p.) injections
of 1,25(OH)2D3 at the same dose in each age group were similar to those observed with oral administration. The time course of the rise in
serum Ca following a single dose of 1,25(OH)2D3, given either orally or i.p., showed that the hypercalcemia was more pronounced and lasted longer in the 9–13-day pups than
in the 16–20-day pups. The results suggest that weaned rats are relatively well protected against hypervitaminosis D and that
younger pups gradually develop such protection during the suckling period. 相似文献
19.
Summary 1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) was recently shown to promote maturation of 5-fluorouracil (5FU)-treated bone marrow cells by up-regulating macrophage-colony stimulating factor (M-CSF) receptors in the presence of interleukin la (IL-1). In order to reveal how 1,25(OH)2D3 interacts with colony-stimulating factors and regulates the differentiation of bone marrow progenitor cell populations, in the present study, natural bone marrow cells were isolated from untreated mice and used in a-minimum essential medium supplemented with 20% heat-inactivated horse serum without added appropriate cytokines. Under the conditions, cells spontaneously differentiated gradually with days of culture, as assessed by expression of macrophage differentiation antigens such as Mac-1 (CD11b) and F4/80. Both M-CSF and granulocyte macrophage-colony stimulating factor (GM-CSF) induced only Mac-1 antigen expression. Simultaneous treatment with M-CSF and 1,25(OH)2D3 enhanced the M-CSF's effect on expression of both antigens, although (1,25(OH)2D3) per se has no effect on the expression for up to 11 days. In addition, successive treatment with 1,25(OH)2D3 and M-CSF or GM-CSF dramatically enhanced expression of both antigens or Mac-1 antigen, respectively. Similarly, both simultaneous and successive treatment with 1,25(OH)2D3 and M-CSF significantly enhanced phagocytic activity and H2O2 production, whereas successive treatment with (1,25(OH)2D3) and GM-CSF significantly enhanced only phagocytic activity. Enzymehistochemical study demonstrated that cells treated simultaneously or successively with 1,25(OH)2D3 and M-CSF were strongly positive for nonspecific esterase (NSE), a macrophage-specific marker, and that simultaneous or successive treatment with 1,25(OH)2D3 and GM-CSF yielded cells strongly positive for NSE or for chloroacetate esterase (ChAE), a granulocyte-specific marker, respectively. These findings suggest that 1,25(OH)2D3 primes bone marrow progenitor cell populations not only to M-CSF but also to GM-CSF and thereby accelerates the CSFs-dependent differentiation of the cells to the macrophage or granulocyte. 相似文献
20.
Monolayer cultures of normal human bone cells contain multiple subpopulations of alkaline phosphatase positive cells 总被引:5,自引:0,他引:5
Toshikatsu Matsuyama K. -H. William Lau Jon E. Wergedal 《Calcified tissue international》1990,47(5):276-283
Summary Cytochemical staining of normal human bone cells in monolayer cultures for alkaline phosphatase (ALP) indicated that the cultures
contained mixed-cell populations. Time course evaluations of the cytochemical staining revealed, in addition to the ALP-negative
cell population, at least two subpopulations of ALP-positive human bone cells with different levels of ALP. A cytochemical
method has been developed which separates the ALP-positive cells into high and intermediate ALP subpopulations. In this method,
human bone cells were stained for ALP using an azo-dye method and incubating at 4°C for 10 and 30 minutes, respectively. We
defined the cell population that stained positively for ALP at 10 minutes as strong ALP-positive cells, and both strong and
intermediate cells were stained at 30 minutes. The intermediate cells were determined from the difference between the values
at the two time points. The intra- and interassay variations of the assay, with the same investigator in blinded investigations,
were both less than 10% and the interobserver variation was approximately 25%. Analysis of the distribution of ALP levels
in cells with a laser densitometer confirmed the presence of at least three cell subpopulations. 1,25(OH)2D3 treatment increased the proportions of both ALP-positive cell populations, whereas TGF-beta treatment increased only the
intermediate ALP-positive cell population. On the contrary, fluoride increased the proportion of the strong ALP cells, and
IGF-1 had no effect on the proportions of either ALP-positive subpopulation. When the ALP-specific activity was compared with
the percentage of each ALP-positive subpopulations for the cells treated with effectors, the ALP-specific activity correlated
with the total ALP-positive and with the strong ALP-positive populations but not with the intermediate ALP-positive subpopulation.
In summary, this study represents the first evidence that normal human bone cells in monolayer cultures contained at least
two subpopulations of ALP-positive cells, and that bone cell effectors could have differential effects on each cell population. 相似文献