| 11. |
- Flodgren, G, et al.
(författare)
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Bone mineral density in flatwater sprint kayakers.
- 1999
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Ingår i: Calcified Tissue International. - 0171-967X .- 1432-0827. ; 64:5, s. 374-379
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Tidskriftsartikel (refereegranskat)abstract
- To elucidate the possible skeletal benefits of the muscular contractions and the nonweight-bearing loading pattern associated with kayaking, we investigated the bone mineral density (BMD, g/cm2) of 10 elite kayakers, six males and four females, with a median age of 19 years. Each subject was compared with the mean value of two matched controls. BMD of the total body, head, ribs, humerus, legs, proximal femur (neck, wards, trochanter), spine, lumbar spine, and bone mineral content (BMC, g), of the arms was obtained using a dual energy X-ray absorptiometer (DXA). Body composition was also assessed. The kayakers had a significantly (P < 0.05-0.01) greater BMD in most upper body sites: left and right humerus (10.4% and 11. 7%), respectively, ribs (6.4%), spine (10.9%), and a greater BMC of the left and right arm (15.7% and 10.6%, respectively). No significant differences in the BMD of the total body, head, or any of the lower body sites were found, except for the pelvis, which was significantly greater in kayakers (5.1%). The controls had a significantly lesser lean body mass (10.4%) and greater percentage of body fat (19.5%) than the kayakers. Bivariate correlation analysis in the controls demonstrated significant and strong relationships between BMD in upper body sites and lean body mass, weight, and fat; the effects of training seem to outweigh most such relationships in kayakers. In conclusion, it seems that the loading pattern and muscular contractions associated with kayaking may result in site-specific adaptations of the skeleton.
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| 12. |
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| 13. |
- Kaastad, T S, et al.
(författare)
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Effects of clodronate on cortical and trabecular bone in ovariectomized rats on a low calcium diet
- 1997
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 1432-0827 .- 0171-967X. ; 61:2, s. 158-164
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the contribution of a low calcium diet to the cortical and trabecular osteoporosis seen in ovariectomized rats after 7 weeks on a low calcium diet and to investigate the effects of the bisphosphonate clodronate on this development of osteoporosis. Thirty-six mature, female Wistar rats were randomized into four groups: Ovx-B (bisphosphonate) and Ovx-C (control) were ovariectomized, and Sham-Ca (low calcium) and Sham+Ca (normal calcium) were sham operated. The first three groups were fed a low calcium diet (0.01%) and Sham+Ca normal rat chow (Ca 1.1%). The Ovx-B received 10 mg/kg s.c. clodronate daily for nine weeks, and Ovx-C, Sham-Ca, and Sham+Ca received the same volumes of saline. Bone mineral turnover measured as 85Sr-uptake was increased in all low calcium groups compared to Sham+Ca. The Sham+Ca femora had higher dry weight and ash weight than the other groups, and Ovx-C had higher dry weight compared with Ovx-B and Sham-Ca. Calcium content was lower in both Ovx groups compared to both Sham groups. Magnesium was lower in all groups compared to Sham+Ca and higher in Ovx-B compared with Ovx-C. In the femoral shaft, Sham+Ca had significantly higher ultimate bending moment, energy absorption, and deflection compared to the other three groups. Ultimate bending moment was higher in Sham-Ca than in Ovx-C. Stiffness was increased in both Sham+Ca and Ovx-B compared to Ovx-C. The maximum stress in the femoral midshaft was higher in Sham+Ca than in the other groups, and higher in Ovx-B than in Ovx-C. Histomorphometry showed increased medullary area in all low calcium groups compared to Sham+Ca and larger cortical area in Sham+Ca and Ovx-B compared to Ovx-C. Compared to Sham+Ca the trabecular bone volume was decreased to 30% in Sham-Ca and to 9% in Ovx-C, but was unchanged in Ovx-B. The low calcium diet generally increased bone mineral turnover and reduced the tibial bone volume. Femoral changes led to a reduction of cortical fracture strength and maximal stress. Ovariectomy in addition to a low calcium diet reduced femoral strength even more. Daily injections of clodronate to ovariectomized rats on a low calcium diet increased femoral shaft stiffness and maximum stress, and clodronate preserved both trabecular and cortical tibial bone volume completely.
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| 14. |
- Kindmark, Andreas, et al.
(författare)
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Inhibitory effects of 9-cis and all-trans retinoic acid on 1,25(OH)2 vitamin D3 induced bone resorption
- 1995
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Ingår i: Calcified Tissue International. - 0171-967X .- 1432-0827. ; 57:3, s. 242-244
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Tidskriftsartikel (refereegranskat)abstract
- The effects of retinoic acid (RA), and calcitriol are mediated by specific nuclear receptors (RARs and VDR, respectively). Induction of RAR and VDR responsive elements in target genes requires a cofactor, the retinoid-X-receptor (RXR), with its ligand 9-cis RA. We have previously demonstrated the expression of RARs and RXRs in osteoblasts, and herein investigated the effects of the retinoids all-trans RA and 9-cis RA alone and combined with calcitriol on bone resorption in vitro, measured by 45Ca-release from prelabeled neonatal mouse calvarial bones. All-trans RA and 9-cis RA were powerful stimulators of bone resorption and essentially equipotent. At threshold concentrations (1 nM) both 9-cis RA and at-RA markedly inhibited the resorption induced by calcitriol (1 pM). The findings are compatible with a physiological role for retinoids in bone metabolism.
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| 15. |
- Lidén, Maria, et al.
(författare)
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Polymorphism at the Sp 1 binding site in the collagen type I alpha 1 gene does not predict bone mineral density in postmenopausal women in sweden
- 1998
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 63:4, s. 293-295
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Tidskriftsartikel (refereegranskat)abstract
- Polymorphisms at the binding site of the Sp 1 transcription factor of the collagen type I alpha1 gene have recently been suggested to be an important marker for low bone mineral density (BMD) and vertebral fracture in a population of predominantly postmenopausal British women. We examined whether the unfavorable "s" allele was associated with low BMD in 64 patients with primary osteoporosis and in 72 healthy controls. We found no statistically significant differences between COLIA1 genotypes with regard to BMD at the spine and femoral neck. In 36 patients with severe osteoporosis with vertebral fracture the genotype frequencies were similar to that observed in 67 age-matched controls. These data indicate that the Sp 1 polymorphisms in the COLIA1 gene are unlikely to be of clinical value in identifying Swedish subjects who are at risk of postmenopausal osteoporosis.
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| 16. |
- Michaëlsson, Karl, 1959-, et al.
(författare)
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Diet, bone mass, and osteocalcin : A cross-sectional study
- 1995
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Ingår i: Calcified Tissue International. - 0171-967X .- 1432-0827. ; 57:2, s. 86-93
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Tidskriftsartikel (refereegranskat)abstract
- To determine the relationships among nutrients intake, bone mass, and bone turnover in women we have investigated these issues in a population-based, cross-sectional, observational study in one county in central Sweden. A total of 175 women aged 28-74 at entry to the study were included. Dietary assessment was made by both a semiquantitative food frequency questionnaire and by four 1-week dietary records. Dual energy X-ray absorptiometry was performed at five sites: total body, L2-L4 region of the lumbar spine, and three regions of the proximal femur. Serum concentrations of osteocalcin (an osteoblast-specific protein reflecting bone turnover) were measured by a radioimmunoassay. Linear regression models, with adjustment for possible confounding factors were used for statistical analyses. A weak positive association was found between dietary calcium intake as calculated from the semiquantitative food frequency questionnaire and total body bone mineral density (BMD) among premenopausal women. No association emerged between dietary calcium intake and site-specific bone mass, i.e., lumbar spine and femoral neck, nor was an association found between dietary calcium intake and serum osteocalcin. BMD at some of the measured sites was positively associated with protein and carbohydrates and negatively associated with dietary fat. In no previous studies of diet and bone mass have dietary habits been ascertained so carefully and the results adjusted for possible confounding factors. Neither of the two methods of dietary assessment used in this study revealed any effect of calcium intake on BMD at fracture-relevant sites among these healthy, mostly middle-aged women. A weak positive association was found between calcium intake estimates based on the food frequency questionnaire and total body BMD. In this study population the preventive effect of high dietary calcium on osteoporosis is probably very weak. The independent significance of protein, carbohydrates, and fat is uncertain.
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| 17. |
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| 18. |
- Pettersson, Ulrika, et al.
(författare)
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A comparison of bone mineral density and muscle strength in young male adults with different exercise level.
- 1999
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Ingår i: Calcified Tissue International. - 0171-967X .- 1432-0827. ; 64:6, s. 490-8
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate any differences in bone mass at different sites between young adults subjected to a high physical activity and a group of young adults with a low level of physical activity. In addition, we compared the relationship among bone mass, muscle strength, and body constitution in these two groups. The reference group consisted of 20 men, age 24.6 +/- 2.3 years, not training for more than 3 hours per week. The ice hockey players consisted of 20 players, age 23.4 +/- 4.9 years, from an ice hockey team in the second highest national Swedish league, training for about 10 hours per week. The groups were matched according to age, height, and weight. Areal bone mineral density (BMD) was measured in total body, head, humerus, spine, pelvis, femur, femoral neck, Ward's triangle, trochanter, femur diaphysis, proximal tibia, and tibia diaphysis using dual energy X-ray absorptiometry. BMD was significantly higher in the total body (8.1%), humerus (11.4%), spine (12.7%), pelvis (12.4%), femoral neck (10.3%), femur (7.4%), proximal tibia (9.8%), and tibia diaphysis (7.5%) in the high activity group. Fat mass was significantly lower in the high activity group (18.7%). The high activity group also had a significantly higher lean body mass (5.4%) and a significantly higher isokinetic muscle strength of the quadriceps muscle compared with the reference group. In the reference group, there was a general strong independent relationship between muscle strength of the thigh and all BMD sites, except for the head, tibia diaphysis, and proximal tibia. Furthermore, in the same group, body mass index (BMI) independently predicted pelvis BMD. On the contrary, in the high activity group, muscle strength did not predict any BMD site at all. In the same group, body constitutional parameters (weight, height, and fat mass) independently predicted pelvis BMD, and BMI was shown to be an independent predictor of humerus BMD. The differences in BMD between the groups seem to be site-specific and may be associated with the type and magnitude of loading during off season training and preferentially during ice hockey. High physical activity seems to weaken the relationship between BMD and muscle strength. Hence, impact forces may be of greater importance in regulating bone mass than muscle strength in itself in highly trained athletes.
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| 19. |
- Pettersson, Ulrika, et al.
(författare)
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Low bone mass density at multiple skeletal sites, including the appendicular skeleton in amenorrheic runners
- 1999
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 64:2, s. 117-125
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate any difference in bone mass at different sites between female long-distance runners with amenorrhea and those with eumenorrhea. We compared 10 amenorrheic and 10 eumenorrheic athletes to determine whether athletes with amenorrhea have lower BMD in multiple skeletal regions, including weight-bearing lower limbs. The amenorrheic group had experienced menstrual dysfunction ranging from 3 to 43 months. As a further control group, 16 eumenorrheic soccer players were compared with the former two running groups regarding their BMD measurements. The two groups were matched for age, height, and amount of training. Areal bone mineral density (BMD) was measured and was found to be significantly lower in the total body, humerus, spine, lumbar spine, pelvis, femoral neck, trochanter, total femur, femur diaphysis, tibia diaphysis and in the nonweight-bearing head of the femur in the amenorrheic group. Body weight, BMI, fat mass, and body fat percent were significantly lower in the amenorrheic group. The differences in the BMD of the head, humerus, femoral neck, total femur, femur diaphysis, and tibia diaphysis disappeared when adjusted for body weight. Compared with the soccer group, the amenorrheic subjects had significantly lower BMD values at all sites except for the head, Ward's triangle, and femur diaphysis. Blood samples were obtained in the two running groups for analysis of osteocalcin, carboxy terminal telopeptide (ICTP), procollagen I (PICP), and estradiol. There were no significant differences between the groups but there was a strong tendency towards a lower estradiol level and a higher osteocalcin level in the amenorrheic group. A free estradiol index (FE2) was derived as the ratio of estradiol to sex hormone binding globulin (SHBG) and was significantly lower in the amenorrheic group. No difference in their daily intake of total energy, protein, carbohydrates, fiber, calcium, and vitamin D was observed. However, both groups showed a surprisingly low energy intake in relation to their training regimens. Stepwise regression analyses revealed that weight was the best predictor of spine BMD in both groups. Estradiol and FE2 were significant predictors of the BMD of the proximal femur in the eumenorrheic group, but did not predict any BMD site in the amenorrheic group. In conclusion, amenorrhea in athletic women affects trabecular and cortical bone in both axial and appendicular skeleton. However, some of the discrepancy can be explained by a lower body weight. Physical weight-bearing activity does not seem to completely compensate for the side effects of reduced estrogen levels even in weight-bearing bones in the lower extremity and spine.
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| 20. |
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