Biomedical subjects

Merja Kärkkäinen

Publications and source records attributed to Merja Kärkkäinen.

8 recordsLinked to original sources

PubMed2006

A seasonal variation of calcitropic hormones, bone turnover and bone mineral density in early and mid-puberty girls - a cross-sectional study.

The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11.4 (sd 0.4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (P < 0.01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r -0.325, P < 0.001). Moreover, the BMD in the femur (P = 0.047) and to a lesser extent in vertebrae (P = 0.057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7.0-7.6 % difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.

Adolescent↗

PubMed2006

How much vitamin D3 do the elderly need?

BACKGROUND: Vitamin D insufficiency poses a problem in many parts of the world, the elderly being an especially vulnerable group. This insufficiency results from an inadequate amount of sunshine and a low dietary intake of vitamin D. Typically, insufficiency is accompanied with high intact parathyroid hormone, (S-iPTH) concentrations. AIMS OF THE STUDY: We studied how serum 25-hydroxy vitamin D (S-25-OHD) concentrations respond to different doses of vitamin D3 supplementation. Secondly to determine the smallest efficient dose to maintain serum 25-OHD concentration above the insufficiency level. We also studied which dose would be efficient in decreasing S-iPTH concentration in these subjects. SUBJECTS AND METHODS: Forty-nine 65- to 85-year-old women participated. The women were randomly assigned into one of four groups receiving 0 (placebo), 5, 10 or 20 microg of vitamin D3 daily for 12 weeks. Fasting morning blood was drawn at the beginning of the study, and thereafter every second week. Calciotropic variables were assessed from serum and urine samples. RESULTS: The S-25-OHD concentration increased significantly (p < 0.001) in all supplemented groups [5 microg: by 10.9 (8.5) nmol/L, 10 microg: by 14.4 (6.9) nmol/L, 20 microg: by 23.7 (11.9) nmol/L], whereas it decreased in the placebo group by 8.3 (13.2) nmol/L. Equilibrium in S-25-OHD concentration was reached in all groups after 6 weeks of supplementation at 57.7 (8.9) nmol/L, 59.9 (8.9) nmol/L and 70.9 (8.9) nmol/L in the groups with increasing vitamin D supplementation. The dose-response to supplementation decreased with increasing vitamin D status at baseline, r = -0.513, p = 0.002. S-iPTH tended to decrease in those with highest dose response to supplementation. CONCLUSIONS: A clear dose response was noted in S-25-OHD to different doses of vitamin D3. The recommended dietary intake of 15 microg is adequate to maintain the S-25-OHD concentration around 40-55 nmol/L during winter, but if the optimal S-25-OHD is higher than that even higher vitamin D intakes are needed. Interestingly, subjects with lower vitamin D status at baseline responded more efficiently to supplementation than those with more adequate status.

Aged↗

PubMed2006

A positive dose-response effect of vitamin D supplementation on site-specific bone mineral augmentation in adolescent girls: a double-blinded randomized placebo-controlled 1-year intervention.

UNLABELLED: The effect of vitamin D supplementation on bone mineral augmentation in 212 adolescent girls with adequate calcium intake was studied in a randomized placebo-controlled setting. Bone mineral augmentation determined by DXA increased with supplementation both in the femur and the lumbar vertebrae in a dose-responsive manner. Supplementation decreased the urinary excretion of resorption markers, but had no impact on formation markers. INTRODUCTION: Adequate vitamin D intake protects the elderly against osteoporosis, but there exists no indisputable evidence that vitamin D supplementation would benefit bone mineral augmentation. The aim of this 1-year study was to determine in a randomized double-blinded trial the effect of 5 and 10 microg vitamin D3 supplementation on bone mineral augmentation in adolescent girls with adequate dietary calcium intake. MATERIALS AND METHODS: Altogether, 228 girls (mean age, 11.4 +/- 0.4 years) participated. Their BMC was measured by DXA from the femur and lumbar spine. Serum 25-hydroxyvitamin D [S-25(OH)D], intact PTH (S-iPTH), osteocalcin (S-OC), and urinary pyridinoline (U-Pyr) and deoxypyridinoline (U-Dpyr) were measured. Statistical analysis was performed both with the intention-to-treat (IT) and compliance-based (CB) method. RESULTS: In the CB analysis, vitamin D supplementation increased femoral BMC augmentation by 14.3% with 5 microg and by 17.2% with 10 microg compared with the placebo group (ANCOVA, p = 0.012). A dose-response effect was observed in the vertebrae (ANCOVA, p = 0.039), although only with the highest dose. The mean concentration of S-25(OH)D increased (p < 0.001) in the 5-microg group by 5.7 +/- 15.7 nM and in the 10-microg group by 12.4 +/- 13.7 nM, whereas it decreased by 6.7 +/- 11.3 nM in the placebo group. Supplementation had no effect on S-iPTH or S-OC, but it decreased U-DPyr (p = 0.042). CONCLUSIONS: Bone mineral augmentation in the femur was 14.3% and 17.2% higher in the groups receiving 5 and 10 microg of vitamin D, respectively, compared with the placebo group, but only 10 mug increased lumbar spine BMC augmentation significantly. Vitamin D supplementation decreased the concentration of bone resorption markers, but had no impact on bone formation markers, thus explaining increased bone mineral augmentation. However, the positive effects were noted with the CB method but not with IT.

Biomarkers↗

PubMed2004

Effects of long-term intervention with Lactobacillus helveticus-fermented milk on bone mineral density and bone mineral content in growing rats.

BACKGROUND: Lactobacillus helveticus-fermented milk has been shown to increase calcium absorption compared to ordinary sour milk. In the present study the possible effect of L. helveticus-fermented milk on bone was studied in growing rats. METHODS: Spontaneously hypertensive male rats, which develop an osteoporotic bone disorder with age, were randomized into 5 groups (n = 10) receiving milk fermented with L. helveticus 16H and, as reference drinks, milk fermented with L. helveticus and Saccharomyces cerevisiae, sour milk, skim milk or water, for 14 weeks. After the intervention bone mineral density and bone mineral content were measured by dual-energy X-ray absorptiometry. The femur weight, length and volume were measured before ashing. From the ashes the weight and mineral content were assessed. RESULTS: As the body weight gain differed significantly between the groups, the results were related to the body weight. The L. helveticus-fermented milk intervention significantly increased the bone mineral density and bone mineral content compared to the sour milk, skim milk and water interventions. The mean values of the bone mineral density and bone mineral content were higher in the L. helveticus-fermented milk group compared to the Saccharomyces-fermented milk group but the difference was not statistically significant. CONCLUSION: L. helveticus-fermented milk increases bone mineral density and bone mineral content in relation to body weight in the long-term feeding of growing rats. The mechanism of L. helveticus remains to be discovered.

Absorptiometry, Photon↗

PubMed2003

Caseinphosphopeptides in milk and fermented milk do not affect calcium metabolism acutely in postmenopausal women.

BACKGROUND: Caseinphosphopeptides (CPPs) are formed in food processing or during digestion in the gastrointestinal tract. CPPs prevent the formation of insoluble calcium salts; thus, the hypothesis is that CPPs increase the absorption of calcium. OBJECTIVE: We examined the effect of additional caseinphosphopeptides in milk and fermented milk on acute calcium metabolism by measuring intact PTH (iPTH), ionized calcium (iCa), total calcium (Ca) and phosphate (P) from serum, and 24-hour calcium from urine (U-Ca). METHODS: The study consisted of two separate parts, both applying a double-blind randomized crossover study with two interventions, in nine postmenopausal women. The acute effect on calcium metabolism was analysed by measuring iPTH, iCa, Ca and P from serum during the first six hours after the administration of the study milks. U-Ca was analysed 24 hours prior to the study and 0, 2, 4, 6, 12 and 24 hours after the administration of the study milks. The study included two parts, both consisting of two study days with a one-week washout period in between. In the first part the effect of control milk and CPP-enriched milk was measured. The second part evaluated the effect of fermentation by giving subjects milk or fermented milk, both enriched with CPPs. RESULTS: In the first part of the study there were no statistically significant differences in iPTH, iCa, Ca, P or U-Ca between the groups receiving control milk compared to CPP-containing milk. There was no difference in the AUC((0-6)) of iCa and iPTH. In the second part, fermentation did not affect calcium metabolism, when results from the CPP-enriched milk and CPP-enriched fermented milk groups were compared. CONCLUSION: One gram of caseinphosphopeptides does not affect calcium metabolism acutely in postmenopausal women.

Aged↗

PubMed2003

Association of low 25-hydroxyvitamin D concentrations with elevated parathyroid hormone concentrations and low cortical bone density in early pubertal and prepubertal Finnish girls.

BACKGROUND: Very few studies have evaluated both parathyroid hormone (PTH) and 25-hydroxyvitamin D [25(OH)D] and their effects on bone mass in children. OBJECTIVE: We studied the associations of serum 25(OH)D and intact PTH (iPTH) with bone mineral content (BMC) and bone mineral density (BMD) at different bone sites and the relation between serum 25(OH)D and iPTH in early pubertal and prepubertal Finnish girls. DESIGN: The subjects were 10-12-y-old girls (n = 193) at Tanner stage 1 or 2, who reported a mean (+/- SD) dietary calcium intake of 733 +/- 288 mg/d. 25(OH)D, iPTH, tartrate-resistant acid phosphatase 5b (TRAP 5b), urinary calcium excretion, BMC, areal BMD, and volumetric BMD were assessed by using different methods. RESULTS: Thirty-two percent of the girls were vitamin D deficient [serum 25(OH)D < or = 25 nmol/L], and 46% of the girls had an insufficient concentration (26-40 nmol/L). iPTH and TRAP 5b concentrations were significantly higher in the deficient group than in the insufficient and sufficient groups [iPTH: 43.9 +/- 15.7 compared with 38.6 +/- 11.2 pg/L (P = 0.049) and 32.7 +/- 12.1 pg/L (P < 0.001), respectively; TRAP 5b: 12.2 +/- 2.9 compared with 11.0 +/- 2.8 U/L (P = 0.009) and 10.9 +/- 1.9 U/L (P = 0.006), respectively]. The girls in the deficient group also had significantly lower cortical volumetric BMD of the distal radius (P < 0.001) and tibia shaft (P = 0.002). High iPTH concentrations were also associated with low total-body apparent mineral density and urinary calcium excretion (P < 0.007). CONCLUSIONS: Vitamin D-deficient girls have low cortical BMD and high iPTH concentrations, which are consistent with secondary hyperparathyroidism. A low vitamin D concentration accompanied by high bone resorption (TRAP 5b) may limit the accretion of bone mass in young girls.

Acid Phosphatase↗

PubMed2002

Functionality of endogenous folates from rye and orange juice using human in vivo model.

BACKGROUND: Cereals contribute about a quarter of the daily folate intake from a typical diet in several European countries. However, studies on bioavailability of endogenous folates, in particular of cereal sources, are scarce. AIM OF THE STUDY: We aimed to study how well natural folates from rye (different rye breads and muesli made of malted rye) and orange juice function in improving folate status of human volunteers compared to a diet containing folic acid fortified wheat bread. METHODS: Healthy human volunteers aged 20-66 y took part in a four-week intervention trial in which bread, breakfast cereal and juice were provided. The study had a parallel design with two groups, 1) rye and orange juice group (33 volunteers) and 2) fortified wheat bread and apple juice group (31 volunteers). The test foods provided on average 184 microg and 188 microg folate per day in rye and wheat groups, respectively. Test foods were consumed as part of the subjects' normal diet. RESULTS: In both groups statistically significant increases in serum and red cell folates were observed after the intervention period. The serum folate increased 26 % and 31 %, and red cell folate levels increased 17 % and 15 % in rye and orange juice and wheat and apple juice groups, respectively. The effects did not differ between the rye and wheat groups. Increases in serum and red cell folate were more profound among subjects with low starting folate levels. Decrease in the plasma homocysteine concentrations was observed only in the highest tertile of both groups but not in the group means. CONCLUSIONS: Endogenous folates incorporated into a healthy diet, even in moderate amounts, is an efficient way to improve folate status among healthy adults. Folates from different rye products and orange juice showed good bioavailability that was similar to folic acid from fortified white bread.

Adult↗

PubMed2002

Vitamin D receptor gene BsmI-polymorphism in Finnish premenopausal and postmenopausal women: its association with bone mineral density, markers of bone turnover, and intestinal calcium absorption, with adjustment for lifestyle factors.

Bone mineral density (BMD) is regulated by genetic and environmental factors. Sixty percent to 80% of bone mass is suggested to be under polygenetic control, but the role of individual genes seems to be modest. Several studies have indicated that the vitamin D receptor ( VDR) gene has a role in the regulation of BMD and bone metabolism, but the results are very controversial. We studied the associations between BsmI-polymorphism of the VDR gene and BMD and bone metabolism in 24 premenopausal (aged 22-45 years) and 69 postmenopausal (aged 48-65 years) Finnish women. The BMD of the lumbar spine and femoral neck and bone turnover markers were measured, and the intestinal calcium absorption was investigated, using a method based on the absorption of non-radioactive strontium. The genotype distribution was 16%, BB; 34.5%, Bb; and 49.5%, bb, which differs from the genotype distribution found in other Caucasian populations, but is similar to earlier Finnish reports. The winter value of 25-hydroxyvitamin-D (25-OH-D) was highest for the BB genotype in both age groups (analysis of covariance [ANCOVA]; premenopausal women P = 0.5, postmenopausal women P = 0.03, and for the groups combined P = 0.02). Lumbar spine BMD and intestinal strontium absorption were highest for the BB genotype in both age groups, but these results were nonsignificant. The markers of bone metabolism did not differ significantly between the VDR genotypes. The BB genotype had the best vitamin D status, which could explain the differences in calcium absorption between the genotypes. However, the conclusions of our study are limited because of the small number of subjects.

Adult↗