| 11. |
- Johansson, Sara, 1973-
(författare)
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Vitamin A and Osteoporosis : Experimental and Clinical Studies
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vitamin A in high doses is severely toxic to the rat skeleton, and the active metabolite retinoic acid (RA) can induce bone resorption in vitro. An excessive dietary intake of vitamin A has been associated with reduced bone mineral density and an increased risk of hip fracture. In this thesis, mechanisms of vitamin A toxicity have been investigated.In the human osteosarcoma cell line MG-63 and in human primary osteoblast-like cultures, stimulation with RA decreased expression of osteoprotegerin (OPG), a potent inhibitor of osteoclast formation and activity. Expression of receptor activator of NF-κΒ ligand (RANKL), which stimulates osteoclastogenesis, was induced. This increase of the RANKL/OPG ratio is a likely mechanism of RA-induced bone resorption.An interaction between vitamin A and D was demonstrated in humans for the first time. Fifteen mg retinyl palmitate antagonized the serum calcium-increasing effect of 2 μg 1,25-(OH)2-D3. This antagonism did not appear to be mediated via PTH.Rats with subclinical hypervitaminosis A after 3 months’ exposure to approximately 9,000 IU retinyl palmitate per day had decreased bone strength, as measured by three-point-bending analysis of femur. Bone diameter and volume, but not bone mineral density, were reduced, suggesting the use of measurements other than BMD for evaluation of early hypervitaminosis A. Indirect mechanisms of toxicity may develop over time, since serum levels of other fat-soluble vitamins were decreased.In summary, vitamin A can increase bone fragility in the rat at doses considerably lower than previously shown. The regulation of RANKL/OPG is a likely pathway for direct effects of vitamin A in bone. An antagonistic effect between vitamin A and vitamin D has been demonstrated in humans, suggesting indirect mechanisms for vitamin A toxicity.
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| 12. |
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| 13. |
- Lorefält, Birgitta, 1944-, et al.
(författare)
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Bone mass in elderly patients with Parkinson's disease
- 2007
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 116:4, s. 248-254
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Tidskriftsartikel (refereegranskat)abstract
- Objective - The objective of the present study was to find risk factors for low bone mineral density (BMD) in patients with Parkinson's disease (PD). Material and methods - Twenty-six PD patients and 26 age-and sex-matched healthy controls were assessed twice within a 1-year period. PD symptoms, body weight, body fat mass, BMD, physical activity, smoking and serum concentrations of several laboratory analyses were investigated. Results - BMD in different locations was lower in PD patients compared with their controls and decreased during the investigated year. BMD was lower in PD patients with low body weight. BMD Z-score of trochanter in the PD group was directly correlated to the degree of physical activity and indirectly to the length of recumbent rest. Total body BMD Z-score in the PD group was directly correlated to the degree of rigidity. Serum 25-hydroxy-vitamin D was slightly lower in PD patients. Conclusion - Low body weight and low physical activity were risk factors for low BMD in PD, while rigidity seemed to be protective. © 2007 The Authors.
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| 14. |
- Lorefält, Birgitta, et al.
(författare)
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Factors of importance for weight loss in elderly patients with Parkinson's disease
- 2004
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 110:3, s. 180-187
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Tidskriftsartikel (refereegranskat)abstract
- Objective – Weight loss is reported frequently in patients with Parkinson's disease (PD). The objective of this study was to find the underlying factors of this phenomenon.Participants and methods – Twenty-six l-dopa-treated patients with PD and 26 age- and sex-matched healthy controls were assessed twice within a 1-year interval. Body weight, body fat mass, resting energy expenditure, physical activity, energy intake, thyroid hormones and cognitive function were investigated.Results – Nineteen (73%) of the PD patients lost body weight, although energy intake and the time for rest increased. Weight loss was most marked in patients with more severe PD symptoms and in whom cognitive function had decreased. Multiple regression analyses showed that determinants for weight loss were female gender, age and low physical activity.Conclusion – Weight loss was common in PD patients, in spite of the increased energy intake and was most obvious in patients with increased PD symptoms and decreased cognitive function.
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| 15. |
- Lorefält, Birgitta, et al.
(författare)
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Weight Loss, Body Fat Mass, and Leptin in Parkinsons Disease
- 2009
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Ingår i: MOVEMENT DISORDERS. - : Wiley. - 0885-3185 .- 1531-8257. ; 24:6, s. 885-890
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Tidskriftsartikel (refereegranskat)abstract
- Weight loss is a common problem in Parkinsons disease (PD), but the causative mechanisms behind this weight loss are unclear. We compared 2( PD patients with sex and age matched healthy controls. Examinations were repeated at baseline, after one and after two years. Body fat mass was measured by Dual X-ray Absorptiometry (DXA). Seventy three per cent of the PD patients lost body weight. Loss of body fat mass constituted a considerable part of the loss of body weight. In the patients who lost weight, serum leptin levels were lower than in those who did not lose weight. The relationship between low body fat mass and low leptin levels seems to be relevant, at least for female PD patients. It is reasonable to believe that low leptin levels in these patients could be secondary to the decreased body fat mass.
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| 16. |
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| 17. |
- Löfman, Owe, et al.
(författare)
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Bone Mineral Density in Diagnosis of Osteoporosis : Reference Population, Definition of Peak Bone Mass, and Measured Site Determine Prevalence
- 2000
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Ingår i: Journal of clinical densitometry. - 1094-6950 .- 1559-0747. ; 3:2, s. 177-186
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Tidskriftsartikel (refereegranskat)abstract
- A population-based study was performed in order to compare different definitions of peak bone mass, and to apply the corresponding T-scores for different skeletal sites to a cohort of 70-yr-old women for studying the prevalence of osteoporosis. Bone mineral density (BMD) of the hip, lumbar spine, and forearm was measured by dual X-ray absorptiometry (Hologic 4500) in 296 women ages 16–31 yr and 210 women age 70 yr. Peak bone mass occurred in women in their early 20s at the proximal femur and at 28 and 31 yr at the spine and forearm, respectively. BMD cutoff levels were compared to machine-specific cutoff values for the different sites. When applied to our cohort of 70-yr-old women, the prevalence of osteoporosis at the total hip was 9–25%, depending on which peak bone mass the T-score of – 2.5 was based. The prevalence in the spine was 28–33% and in the forearm 45–67%. Osteoporosis in at least one of the three measured sites was documented in 49–72% of the population sample. Our results show that the use of T-score to define osteoporosis results in a highly different prevalence rate in a given population depending on the reference population and the skeletal sites chosen for measurement.
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| 18. |
- Löfman, Owe, et al.
(författare)
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Bone mineral density in normal Swedish women
- 1997
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Ingår i: Bone. - 8756-3282 .- 1873-2763. ; 20:2, s. 167-174
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Tidskriftsartikel (refereegranskat)abstract
- We examined 429 women, aged 20–80 years, randomly selected from the population register to establish normal values for bone mineral density (BMD) in Swedish women. BMD of the spine and hip was measured by dual-energy X-ray absorptiometry (DEXA; Hologic QDR 1000) and in the forearm by single photon absorptiometry (SPA; Molsgaard ND-1100). The recalled age of menarche was negatively correlated to BMD at all ages. There was no significant change in BMD from 20–49 years at any site except a slight decline at Ward's triangle. Bone loss was rapid at all sites during the first decade after menopause. Thereafter, BMD declined slowly in the trochanter and total hip but more rapidly in the forearm, femoral neck, and Ward's triangle. BMD in the spine even increased in the eighth decade probably due to osteoarthritis. The average change in forearm BMD during the 15 perimenopausal years comprising mean age for menopause ± 2 SD (43–57 years) was −0.4% per year in premenopausal females and −1.6% per year in postmenopausal females. The corresponding annual percental change was, for the spine, +0.2 and −1.7; neck, −0.7 and −1.7; trochanter, +0.5 and −1.5; and Ward's triangle, −0.1% and −2.2%, respectively. Our normal values for lumbar spine BMD prior to menopause did not differ from published values or the manufacturer's normal values; however, our spine BMD values for the first decade after menopause were significantly lower (≈10%) than in other studies. Our femoral neck BMD values for younger women were, like those of several other groups, significantly lower than the manufacturer's normal values, but our sample of young women in this study was small. The prevalence of osteoporosis, if defined as t score < −2.5 is highly dependent on the sampling of the reference population of young adult women, and also on the choice of skeletal site. Further studies on bone mineral density in healthy young adult women are needed.
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| 19. |
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| 20. |
- Löfman, Owe, et al.
(författare)
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Changes in Hip Fracture Epidemiology : Redistribution Between Ages, Genders and Fracture Types
- 2002
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 13:1, s. 18-25
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Tidskriftsartikel (refereegranskat)abstract
- After several reports of increasing hip fracture incidence some studies have suggested a trend-break. In a previous study of hip fractures we forecast a 70% increase in the total number of fractures from 1985 up to year 2000. We therefore studied the incidence trend for the last 15 years and supply a new prognosis up to year 2010. We recorded all incident hip fractures treated in the county of Östergötland, Sweden (≈ 400 000 inhabitants) 1982–96. A total of 11 517 hip fractures in men and women aged 50 years and above were included in the study after cross-validation between a computerized register of radiologic investigations and the hospital records. The projected number of fractures up to year 2010 was estimated by a Poisson regression model, considering both age and year of fracture in every single year 1982–96 for the respective fracture type and gender, and applied to the projected population. The annual number of hip fractures increased by 39% in men and 25% in women during the study period. Amongst men, the age-adjusted incidence of cervical fractures increased from 188 to 220/100 000 and of trochanteric fractures from 138 to 170/100 000. In women the incidence of cervical fractures decreased from 462/100 000 to 418/100 000 and of trochanteric fractures from 407/100 000 to 361/100 000. Cervical/trochanteric fracture incidence rate ratio leveled off, and also the female/male fracture rate ratio declined. A prognosis assuming that the incidence development will continue as during 1982–96, and a population in agreement with the forecast, predicts that the total age- and sex-adjusted number of hip fractures will decrease by 11% up to year 2010 compared with 1996. In women and men, however, a decrease of 19% and an increase of 7% respectively were projected. If the age- and sex-specific incidence remains at the same level as at the end of the study period, no significant change in the total numbers will occur. A trend-break was thus found in hip fracture incidence for women but not for men. Whether this is due to therapeutic and/or preventive measures in women is unknown. According to the most probable scenario a substantial increase in male trochanteric fractures (36%) is expected up to 2010, while all other hip fractures in both genders will decrease by 4–32% resulting in a total reduction of 11%.
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