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 15,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ipriflavone (i.p.) positively affects bone density in postmenopausal osteoporosis, primarily by inhibiting bone resorption. Using in vitro models of human osteoblast differentiation, we have observed that i.p. and some of its metabolites stimulate the expression of bone sialoprotein, decorin, and type I collagen, and facilitate the deposition of mineralized matrix. This suggests that i.p. may stimulate bone formation in addition to its antiresorptive activity. To assess whether these effects translate into an improved bone "quality" in vivo, we measured biomechanical properties, mineral composition, and crystallinity of femurs of 12-week-old, male, Sprague-Dawley rats treated with i.p. for 1 month. i.p. significantly decreased vibration damping, an index of strain energy loss. Because vibration damping increases as bone porosity increases, the results indicate that i.p.-treated bones acquired a higher capacity to withstand dynamic stress. In fact, 1.5-fold higher energy was required to fracture femurs of i.p.-treated rats after a single supramaximal impact. i.p. also increased BMD, assessed by both volume displacement and ash analysis, whereas the relative contents of Ca, P, and Mg in the ashes were not affected. Thus, no gross abnormalities in mineral composition of bone occurred after i.p. administration. As a measure of bone crystallinity, X-ray diffraction analysis was performed. The broadening parameter beta 1/2 for the (310) and (002) reflections was not significantly different between i.p.-treated and control animals. Similarly, there were no differences in serum levels of Ca, Mg, alkaline phosphatase, and type I collagen telopeptides between treated and control animals at the end of the study. Therefore, 1-month treatment with i.p. increased bone density and improved the biomechanical properties of adult male rat bones without altering mineral composition or bone crystallinity.
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PMID:In vitro and in vivo effects of ipriflavone on bone formation and bone biomechanics. 926 10

One thousand male Hubbard chicks were used in a 21-d study (10 birds per battery cage) to determine relative biological availability of phosphorus in seven samples of commercial dicalcium phosphate, expected to contain variable amounts of monocalcium phosphate. Five samples were from established producers in Brazil and two from the U.S. Pure calcium phosphate dibasic dihydrate was used as the reference standard. Phosphates were added to the corn-soybean basal diet (22.5% CP; 0.4% total phosphorus) to provide 0.1, 0.2, and 0.3% supplemental phosphorus. The calcium level was 1.0% for all diets. Left tibias were removed for bone ash (BA) and bone strength (BS) determination. Body weight, feed intake (FI), BA, BS, and plasma phosphorus increased (P < 0.01) and plasma calcium and alkaline phosphatase decreased (P < 0.01) with increasing dietary phosphorus regardless of source. The availability of phosphorus for each test phosphate was determined by slope ratio, with BW, BA, and BS regressed on phosphorus added within each phosphorus source. A relative biological value (RBV) was calculated based on BW, BA, and gain:feed ratio. Availability based on BW ranged from 97.07 to 110.41%. When BA was the criterion, values were 80.32 to 107.84% and for BS were 79.34 to 110.52%. The RBV ranged from 97.55 to 100.60%. Phosphate sources did not vary greatly in phosphorus availability. Overall phosphorus availability averages were higher for BW (103%) and RBV (99%) and lowest for BA (96%) and BS (94%).
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PMID:Biological evaluations of commercial dicalcium phosphates as sources of available phosphorus for broiler chicks. 943 86

Daily oral clodronate treatment was evaluated in Sprague-Dawley rats for its ability to inhibit estrogen-deficiency-induced changes in femoral neck, femoral diaphysis, and lumbar vertebrae (L4-L5). Six-month-old ovariectomized (OVX) rats were administered by gavage a vehicle (Veh) or clodronate (100 or 500 mg/kg/day). Sham-operated (SHAM) control rats received the vehicle (n = 15/group). Treatment was started on the day of operation and continued for 3 months. Trabecular bone volume (BV/TV) and structural variables (trabecular number, Tb.N; thickness, Tb.Th; separation, Tb.Sp; and trabecular bone pattern factor, Tb.Pf) were assessed on secondary spongiosa of the right femoral neck Furthermore, cantilever bending test of the left femoral neck and compression test of L4, ash weight of L5, and morphometric studies of femoral diaphysis were carried out, and serum and urinary markers of bone turnover were determined. The OVX/Veh group had higher levels of serum osteocalcin and alkaline phosphatase and higher urinary excretion of deoxypyridinoline/creatinine than the SHAM/Veh group at 3 months postsurgery, and clodronate reduced these changes. BV/TV of femoral neck, bone mass of L5, and the maximum loads of the femoral neck and L4 were lower after OVX than SHAM operation. Although clodronate prevented trabecular bone loss in the femoral neck and preserved Tb.Pf at the SHAM control level, it failed to preserve the mechanical strength at the femoral neck However, in lumbar vertebrae, clodronate prevented the loss of bone mass and mechanical properties. Furthermore, there was a good positive correlation between maximum load of L4 and the ash weight of L5 (n = 58, r = 0.69, p < 0.001). In the femoral neck (n = 55), Tb.Pf correlated negatively with BV/TV and Tb.N (r = -0.59 and r = -0.55;p < 0.001, respectively) and positively with Tb.Sp (r = 0.61, p < 0.001). In femoral mid-diaphysis, there were no significant changes in cortical bone geometry in any of the groups. We conclude that orally administered clodronate suppresses the enhanced bone turnover in adult OVX rats and preserves trabecular bone volume and connectivity in the femoral neck In the axial skeleton, clodronate has a beneficial effect on lumbar vertebral bone mass and strength.
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PMID:Clodronate prevents osteopenia and loss of trabecular connectivity in estrogen-deficient rats. 949 23

The present study was designed to examine the metabolic changes and early effects of short-term parathyroid hormone (PTH) treatment on bone mass, mineral content, and strength. Forty-eight 10-week-old intact female rats were randomized into six groups. The three PTH-treated groups were subcutaneously given PTH 50 microg/kg body weight daily for 5 (PTH5), 10 (PTH10), or 15 (PTH15) days. The three respective time control groups (C5, C10, and C15) were injected with saline solution. In serum, total calcium, alkaline phosphatase, and insulin-like growth factor-I (IGF-I) were analyzed. Bone mass was estimated with wet and dry weights of the femora and hydroxyproline content of the tibiae. Ash weight and calcium, magnesium, and phosphorus contents (determined by AAS) were used to measure femoral mineral content. Bone mineral density (BMD) of the femora was measured using dual-energy X-ray absorptiometry (DXA) and the biomechanical properties of the femoral neck were tested. After 5 days of PTH treatment, some trends of the anabolic actions of PTH could be observed, but there was no significant effect on relevant parameters of bone formation. After 10 days, bone mass, mineral content (assessed by ash weight), and BMD of the PTH-treated rats were significantly increased compared with those of controls. The relative femoral magnesium content of the PTH-treated animals was significantly higher than that of controls. After 15 days, the length of the femora, bone mass, mineral content, BMD, and the width of the femoral neck were increased, and its biomechanical properties were significantly improved in PTH-treated rats compared with the respective time control group. PTH treatment significantly increased circulating alkaline phosphatase and decreased systemic IGF-I concentrations throughout the study. In conclusion, intermittent PTH administration to still growing female rats is anabolic in bone with significant effects already taking place after 10 days of treatment. The effects of PTH consisted of: (1) an increase in bone mass and mineral content with a transient augmentation of relative magnesium content; and (2) improved width and mechanical properties of the femoral neck after 15 days of treatment. These effects are accompanied by an increase in longitudinal bone growth. They are unlikely related to any changes in systemic IGF-I concentrations.
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PMID:Early effects of short-term parathyroid hormone administration on bone mass, mineral content, and strength in female rats. 951 14

Female Sprague-Dawley rats, 9 weeks of age, were assigned to four groups: Group 0 (n = 8) was dissected for base-line control, and the other three groups were fed for 3 mo: Group 1 (n = 9), sedentary controls; Group 2 (n = 6), running rats housed in a cage with a treadmill and pair-fed with Group 1; and Group 3 (n = 7), running rats, pair-fed and allowed free access to additional glucose. The distances of voluntary running did not significantly differ between Groups 2 and 3. Menstrual cycles in these rats were apparently maintained as observed from daily running distances. The amount of glucose taken by rats in Group 3 was 3.5 +/- 0.4 (mean and SE) g/d. Body weight (BW) at the end of the experiment for Groups 1, 2, and 3 were 295.0 +/- 7.9, 211.7 +/- 5.4 (p < 0.001 vs. Group 1), and 259.0 +/- 3.5 g (p < 0.01 vs. Group 2), respectively. The parameters of bone mass such as ash weights of the femur and bone mineral content of the lumbar spine and the tibia in Groups 1 and 2 did not differ, but the values were significantly greater in Group 3 than in Group 2. However, these parameter values corrected for BW were significantly greater in Group 2 than in Group 1 and did not significantly differ between Groups 2 and 3. The parameters of bone formation, such as serum bone alkaline phosphatase activity levels and trabecular bone formation rates corrected for BW, were significantly greater in Group 2 than in Group 1 but did not differ between Group 2 and 3. However, the parameters of bone resorption, such as serum tartrate resistant acid-phosphatase levels, were significantly less in Group 3 than in Group 2. These results suggest that voluntary running augments the age-dependent increase in bone mass by modulating the bone turnover when an adequate energy source is supplied under conditions of normal menstruation, and an adequate supply of energy could be necessary to enhance the age-dependent increase in bone mass.
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PMID:Modulation of bone mass and turnover in growing rats by voluntary weight-bearing exercise and glucose supplementation. 974 61

Studies on calcium nutrition in appropriate large animal models can be directly relevant to humans. We have examined the effect of dietary Ca deficiency on various bone and bone-related variables, including plasma markers, histomorphometry, mineral content and breaking strength in pigs. Three groups of eight 38-d-old female pigs were fed adequate (0.9%; control), low (0.4%; LCa) or very low (0.1%; VLCa) Ca diets for 32 d. Plasma Ca significantly decreased over time only in the VLCa-deficient pigs. The concentrations of the parathyroid hormones (PTH) and calcitriol increased as Ca deficiency developed, and the plasma PTH and calcitriol levels varied inversely with dietary Ca. The total bone ash contents, bending moments, trabecular bone volume and the mineral apposition rate all decreased as the calcium intake decreased. The osteoclast surface areas were greater than those of controls in both Ca-deficient groups, whereas the osteoblast surface areas were greater only in the VLCa group. The plasma osteoblast-related markers (alkaline phosphatase, carboxy-terminal propeptide of type I procollagen and osteocalcin) were either greater or unaffected in the Ca-deficient pigs. The results indicate that deficient bone mineralization combined with an increased bone resorption led to bone loss and fragility. The differences in the changes in bone cells (number and activity) between LCa and VLCa groups might be due to differences (time and extent) of circulating PTH and calcitriol. The defective mineralization in both Ca-depleted groups resulted mainly from the lack of Ca because their osteoblast activity was either maintained or stimulated. The results also underline the progressive sensitivity of pigs to Ca supply and the usefulness of this model.
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PMID:Calcium-regulating hormones, bone mineral content, breaking load and trabecular remodeling are altered in growing pigs fed calcium-deficient diets. 991 98

To predict the potential utility of calcitriol in human osteoporosis with hepatic dysfunction, we examined the effects of calcitriol and alfacalcidol in ovariectomized (OVX) aged-rats with CCl4-induced hepatic failure. In OVX+CCl4 rats, GOT, GTP, alkaline phosphatase and total bilirubin increased and hepatic enzyme activity (cytochrome b5 and P450) decreased. Repeated oral doses of calcitriol (0.1 and 0.2 microgram/kg) for 51 days inhibited a decrease in serum calcium concentration. This effect was more potent than that of alfacalcidol at the same dose. Both drugs tended to inhibit a decrease in femoral calcium contents. Calcitriol (0.2 microgram/kg) prevented a decrease in femoral bone density (dry and ash weight per volume), unlike alfacalcidol. Soft X-ray imaging analysis revealed that both drugs tended to inhibit the decrease in femoral bone density. There were no differences in the femoral bone strength between OVX+CCl4 and sham-operated rats. The serum calcitriol concentrations increased after the last doses of calcitriol, while they did not increase after the last dose of alfacalcidol. All these effects of calcitriol were related to the serum calcitriol levels. These results suggest that calcitriol, unlike alfacalcidol, may have a clinical therapeutic effect in osteoporosis with hepatic dysfunction.
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PMID:[Effects of calcitriol and alfacalcidol on an osteoporosis model in rats with hepatic failure]. 1009 6

Vitamin D insufficiency is still a concern in countries where there is no routine food supplementation, such as France. A low vitamin D status is clearly associated with an increased risk of fracture in the elderly, but the long-term consequences of latent vitamin D insufficiency in young people and adults are not known. We fed 26 growing pigs a high calcium diet (1.1%) with a 1000 IU cholecalciferol/kg diet (controls), or without vitamin D (0D) for 4 months. We then analyzed the overall impact of low vitamin D status on osteotropic hormones (calcitriol and immunoreactive parathyroid hormone), plasma markers of bone remodeling (alkaline phosphatase [ALP] activity, carboxyterminal propeptide of type I procollagen [PICP], osteocalcin, hydroxyproline), whole bone parameters (ash content, bending moment), histomorphometry, and the populations of marrow osteoblastic and osteoclastic precursors by ex vivo cultures. The fall in plasma 25-dihydroxyvitamin [25(OH)D] in the 0D pigs indicated severe depletion of their vitamin D stores. However, they remained normocalcemic, were mildly hyperparathyroid after 2 months of vitamin D deprivation, and showed only a slight decrease in plasma calcitriol. The bone mineral content and bending moment of metatarsals decreased and they had increased osteoblastic (+59%, p < 0.05 0D vs. controls) and osteoclastic (+31%, p < 0.1 0D vs. controls) surfaces. This was not paralleled by increased bone turnover, because plasma hydroxyproline and ALP were unchanged and PICP and osteocalcin were decreased. The adherent fraction of bone marrow cells showed a great increase in the number of total stromal colony-forming units (CFU-F; +93%, p < 0.05 0D vs. controls) and in the percent of ALP(+) CFU-F (+58%, p < 0.01 0D vs. controls) in cultures from 0D pigs. More tartrate-resistant acid phosphatase-positive (TRAP(+)) multinucleated cells were generated in cultures of nonadherent marrow cells from 0D pigs, and the area of resorption was 345% greater than in controls. Thus, vitamin D deprivation caused only moderate hormonal changes in growing pigs fed a high-calcium diet, but affected their bone characteristics and greatly enhanced the pool of osteoblasts and osteoclasts by stimulating the commitment of their precursors in bone marrow.
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PMID:In vivo bone metabolism and ex vivo bone marrow osteoprogenitors in vitamin D-deprived pigs. 1077 89

Intestinal transference pattern of calcium and associated changes in the activities of intestinal mucosal enzymes, rate of bone turnover and bone metabolism were evaluated in ovariectomized rats exposed to cold stress of various intensities i.e., mild (15 degrees C) or stronger (8 degrees C and 4 degrees C) for 5 min everyday for 7 consecutive days. Except mild cold stress-induced group (15 degrees C), rats of other two groups (8 degrees C and 4 degrees C) showed considerable decrease in the rate of in situ intestinal transference of calcium. Likewise, in these groups, the activities of intestinal mucosal enzymes, alkaline phosphatase (AP) and calcium ATPase (Ca2+-ATPase) were decreased significantly in all the segments of small intestine in a descending gradient. Also significant changes in bone turnover and bone resorption were confirmed in these animals by marked alterations in plasma AP activity, urinary calcium and phosphate excretion and urinary calcium to creatinine ratio (Ca: Cr). The skeletal changes were further ascertained by examining other physical and biochemical parameters of bone metabolism viz., body mass, bone density, ratio of mineral to matrix and mineral content of bone ash (calcium and phosphate) in the ovariectomized rat model. All these results suggest that stronger cold stress (8 degrees C and 4 degrees C) may be an important ecological factor in the development of earlier bone loss in hypogonadal rats.
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PMID:Effects of different intensities of cold stress on certain physiological phenomena related to skeletal health in a hypogonadal rat model. 1122 Apr 94

Three experiments were conducted to determine the effect of dietary vitamin K1 (K1) on selected plasma characteristics and bone ash in poults. In Experiment 1, diets were supplemented with 0, 0.5, 1.0, or 2.0 mg of K1/kg. All diets contained 1,650 IU of vitamin D3 (D3)/kg. Dietary K1 had no effect on tibia ash at 7 d or incidence of a severe, rickets-like condition. Tibia ash of poults fed 2.0 mg of K1/kg, however, was greater at 14 d of age than that of poults fed the basal diet. Dietary inclusion of 0.5 mg of K1/kg was as effective as 1 or 2 mg of K1/kg in reducing plasma prothrombin time. In Experiment 2, a 2 x 4 factorial arrangement was used consisting of 1,650 or 550 IU of D3/kg and 0.1, 0.45, 1.0, and 2.0 mg of K1/kg. Dietary D3 and K1 had no effect on bone ash. Dietary inclusion of 0.1 mg of K1/kg seemed to be enough to minimize plasma prothrombin time. In Experiment 3, dietary treatments consisted of a control (1,650 IU of D3 and 2.0 mg of K1/kg) and K1 concentrations of 0, 0.37, 2.28, or 5.33 mg/kg in diets containing 275 IU of D3/kg. Poults fed the low-D3 diet without K1 consumed less feed, gained less weight, and had increased plasma alkaline phosphatase activity, decreased inorganic phosphorus level, and decreased tibia ash (P < 0.05) compared with those of poults fed the control diet. Feed intake and body weight gain were improved, plasma alkaline phosphatase activity decreased, and plasma inorganic phosphorus increased or tended to increase when poults were fed the low-D3 diet supplemented with 0.37 or 2.88 mg of K1/kg compared with poults fed the low-D3 diet without K1 supplementation. Tibia ash of poults fed the low-D3 diet was not affected by K1 supplementation. The results of this research show that dietary K1 concentration had little, if any, effect on bone development in 1- to 14-d-old turkeys.
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PMID:Effect of dietary vitamin K1 on selected plasma characteristics and bone ash in young turkeys fed diets adequate or deficient in vitamin D3. 1137 10


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