85 research outputs found
Bone mineral density and body composition of children and adolescents in health and disease
Osteoporosis is characterized by low bone mass and microarchitectural deterioration of
bone tissue, leading to enhanced bone fragility and a consequent increase in fracture
risk. Osteoporosis is a major public health problem involving postmenopausal women
and aging individuals. The lifetime risk of osteoporotic fractures of the vertebral
bodies (symptomatic), hip, and distal radius is about 40 % for white women and 13 %
for white men. At present, the best possibility to assess the fracture risk of an
individual is the measurement of bone mass (g) or bone mineral density (BMD, glcm).
Studies in postmenopausal women showed that for each standard deviation decrease in
BMD there was a 2-3 fold increase in fracture risk. Bone mass later in life is
determined by the peak bone mass acquired during adolescence and the subsequent rate
of bone loss. Low peak bone mass results in a higher risk of osteoporosis. A high
peak bone mass provides a larger reserve later in life.
BMD increases during childhood until the peak bone mass is achieved, around the age
of 18 to 20 years. Thereafter, bone mass stabilizes and then decreases progressively
in both sexes after 35 to 40 years of age with a steeper decline in women after the
menopause
Bone mineral density and body composition of children and adolescents in health and disease
Osteoporosis is characterized by low bone mass and microarchitectural deterioration of
bone tissue, leading to enhanced bone fragility and a consequent increase in fracture
risk. Osteoporosis is a major public health problem involving postmenopausal women
and aging individuals. The lifetime risk of osteoporotic fractures of the vertebral
bodies (symptomatic), hip, and distal radius is about 40 % for white women and 13 %
for white men. At present, the best possibility to assess the fracture risk of an
individual is the measurement of bone mass (g) or bone mineral density (BMD, glcm).
Studies in postmenopausal women showed that for each standard deviation decrease in
BMD there was a 2-3 fold increase in fracture risk. Bone mass later in life is
determined by the peak bone mass acquired during adolescence and the subsequent rate
of bone loss. Low peak bone mass results in a higher risk of osteoporosis. A high
peak bone mass provides a larger reserve later in life.
BMD increases during childhood until the peak bone mass is achieved, around the age
of 18 to 20 years. Thereafter, bone mass stabilizes and then decreases progressively
in both sexes after 35 to 40 years of age with a steeper decline in women after the
menopause
Metabolism of carveol and dihydrocarveol in Rhodococcus erythropolis DCL14
Rhodococcus erythropolis DCL14 assimilates all stereoisomers of carveol and dihydrocarveol as sole source of carbon and energy. Induction experiments with carveol- or dihydrocarveol-grown cells showed high oxygen consumption rates with these two compounds and with carvone and dihydrocarvone. (Dihydro)carveol-grown cells of R. erythropolis DCL14 contained the following enzymic activities involved in the carveol and dihydrocarveol degradation pathways of this micro-organism: (dihydro)carveol dehydrogenase (both NAD - and dichlorophenolindophenol-dependent activities), an unknown cofactor-dependent carvone reductase, (iso-)dihydrocarvone isomerase activity, NADPH-dependent dihydrocarvone monooxygenase (Baeyer–Villiger monooxygenase), -lactone hydrolase and an NAD -dependent 6-hydroxy-3-isopropenylheptanoate dehydrogenase. Product accumulation studies identified (4R)-carvone, (1R,4R)-dihydrocarvone, (4R,7R)-4-isopropenyl-7-methyl-2-oxo-oxepanone, (3R)-6-hydroxy-3-isopropenylheptanoate, (3R)-3-isopropenyl-6-oxoheptanoate, (3S,6R)-6-isopropenyl-3-methyl-2-oxo-oxepanone and (5R)-6-hydroxy-5-isopropenyl-2-methylhexanoate as intermediates in the (4R)-carveol degradation pathway. The opposite stereoisomers of these compounds were identified in the (4S)-carveol degradation pathway. With dihydrocarveol, the same intermediates are involved except that carvone was absent. These results show that R. erythropolis DCL14 metabolizes all four diastereomers of carveol via oxidation to carvone, which is subsequently stereospecifically reduced to (1R)-(iso-)dihydrocarvone. At this point also dihydrocarveol enters the pathway, and this compound is directly oxidized to (iso-)dihydrocarvone. Cell extracts contained both (1R)-(iso-)dihydrocarvone 1,2-monooxygenase and (1S)-(iso)-dihydrocarvone 2,3-monooxygenase activity, resulting in a branch point of the degradation pathway; (1R)-(iso-)dihydrocarvone was converted to 4-isopropenyl-7-methyl-2-oxo-oxepanone, while (1S)-(iso)-dihydrocarvone, which in vivo is isomerized to (1R)-(iso-)dihydrocarvone, was converted to 6-isopropenyl-3-methyl-2-oxo-oxepanone. 4-Isopropenyl-7-methyl-2-oxo-oxepanone is hydrolysed to 6-hydroxy-3-isopropenylheptanoate, which is subsequently oxidized to 3-isopropenyl-6-oxoheptanoate, thereby linking the (dihydro)carveol degradation pathways to the limonene degradation pathway of this micro-organism. 6-Isopropenyl-3-methyl-2-oxo-oxepanone is, in vitro, hydrolysed to 6-hydroxy-5-isopropenyl-2-methylhexanoate, which is thought to be a dead-end metabolite
Bone mineral density and body composition before and during treatment with gonadotropin-releasing hormone agonist in children with central precocious and early puberty
Major changes in bone mineral density (BMD) and body composition occur
during puberty. In the present longitudinal study, we evaluated BMD and
calculated volumetric BMD [bone mineral apparent density (BMAD)], bone
metabolism, and body composition of children (32 girls and 2 boys) with
central precocious and early puberty before and during treatment with GnRH
agonist (GnRH). Patients were studied at baseline and during treatment for
6 months (n = 34), 1 yr (n = 33), and 2 yr (n = 16). Lumbar spine and
total body BMD and body composition were measured with dual-energy x-ray
absorptiometry. The variables were compared with age- and sex-matched
reference values of the same population and expressed as SD score (SDS).
Bone age was assessed. Serum calcium, phosphate, alkaline phosphatase,
osteocalcin, the carboxyterminal propeptide of type I collagen (PICP),
cross-linked telopeptide of collagen I (ICTP), 1,25 dihydroxyvitamin D and
urinary hydroxyproline/creatinine, and calcium/ creatinine ratios were
measured. Mean lumbar spine BMD SDS was significantly higher than zero at
baseline (P < 0.02) and did not differ from normal, after 2 yr of
treatment. Mean spinal BMAD SDS and total body BMD SDS were not
significantly different from zero at baseline and had not changed
significantly after 2 yr of treatment. During therapy, fat mass and
percentage body fat SDS increased, whereas lean tissue mass SDS decreased.
Mean lumbar spine BMD and BMAD and total body BMD SDS, calculated for bone
age, were all lower than zero at baseline (BMD P < 0.001 and BMAD P <
0.05) and also after 2 yr treatment (respectively, P < 0.001, P < 0.05,
and P < 0.01). Biochemical bone parameters were significantly higher than
prepubertal values at baseline, and they decreased during treatment. In
conclusion, patients with central precocious and early puberty had normal
BMD for chronological age but low BMD for bone age, after 2 yr of
treatment with GnRH. Bone turnover decreased during treatment. Changes in
body composition resembled those seen in patients with GH deficiency
Bone mineral density in children and adolescents: relation to puberty, calcium intake, and physical activity
The association of height, weight, pubertal stage, calcium intake, and
physical activity with bone mineral density (BMD) was evaluated in 500
children and adolescents (205 boys and 295 girls), aged 4-20 yr. The BMD
(grams per cm2) of lumbar spine and total body was measured with dual
energy x-ray absorptiometry. Lumbar spine volumetric BMD was calculated to
correct for bone size. BMD and volumetric BMD increased with age. During
puberty, the age-dependent increment was higher. After adjustment for age,
the Tanner stage was significantly associated with all three BMD variables
in girls and with spinal BMD in boys. In boys, positive correlations were
found between BMD and both calcium intake and physical activity after
adjustment for age. Stepwise regression analysis with weight, height,
Tanner stage, calcium intake, and physical activity as determinants with
adjustment for age resulted in a model with Tanner stage in girls and
weight in boys for all three BMD variables. The major independent
determinant of BMD was the Tanner stage in girls and weight in boys
Changes in bone mineral density, body composition, and lipid metabolism during growth hormone (GH) treatment in children with GH deficiency
Adults with childhood onset GH deficiency (GHD) have reduced bone mass,
increased fat mass, and disorders of lipid metabolism. The aim of the
present study was to evaluate bone mineral density (BMD), bone metabolism,
body composition, and lipid metabolism in GHD children before and during
2-3 yr of GH treatment (GHRx). Forty children with GHD, mean age 7.9 yr,
participated in the study of bone metabolism and body composition; and an
additional group of 17 GHD children, in the study of lipid metabolism.
Lumbar spine BMD, total body BMD, and body composition were measured with
dual-energy x-ray absorptiometry. Volumetric BMD (bone mineral apparent
density, BMAD) was calculated to correct for bone size. BMD, BMAD, lean
tissue mass, bone mineral content, fat mass, and percentage body fat were
expressed as SD scores (SDS), in comparison with normative data of the
same population. Lumbar spine BMD and BMAD and total body BMD were all
decreased at baseline. All BMD variables increased significantly during
GHRx, lumbar spine BMD SDS, already after 6 months of treatment. Lean
tissue mass SDS increased continuously. Bone mineral content SDS started
to increase after 6 months GHRx. Fat mass SDS decreased during the first 6
months of GHRx and remained stable thereafter. Biochemical parameters of
bone formation and bone resorption did not differ from normal at baseline
and increased during the first 6 months of GHRx. Serum 1,25
dihydroxyvitamin D increased continuously during GHRx, whereas PTH and
serum calcium remained stable. Lipid profile was normal at baseline:
Atherogenic index had decreased and apolipoprotein A1(Apo-A1) had
increased after 3 yr of treatment. In conclusion, children with GHD have
decreased bone mass. BMD, together with height and lean tissue mass,
increased during GHRx. GHRx had a beneficial effect on lipid metabolism
Longitudinal follow-up of bone density and body composition in children with precocious or early puberty before, during and after cessation of GnRH agonist therapy
We studied bone mineral density (BMD), bone metabolism, and body
composition in 47 children with central precocious puberty (n = 36) or
early puberty (n = 11) before, during, and after cessation of GnRH
agonist. Bone density and body composition were measured with dual energy
x-ray absorptiometry and expressed as SD scores. Bone age and biochemical
parameters of bone turnover were assessed. Measurements were performed at
baseline, after 6 months, and on a year
Indices from flow-volume curves in relation to cephalometric, ENT- and sleep-O2 saturation variables in snorers with and without obstructive sleep-apnoea
In a group of 37 heavy snorers with obstructive sleep apnoea (OSA, Group
1) and a group of 23 heavy snorers without OSA (Group 2) cephalometric
indices, ENT indices related to upper airway collapsibility, and nocturnal
O2 desaturation indices were related to variables from maximal expiratory
and inspiratory flow-volume (MEFV and MIFV) curves. The cephalometric
indices used were the length and diameter of the soft palate (spl and
spd), the shortest distance between the mandibular plane and the hyoid
bone (mph) and the posterior airway space (pas). Collapsibility of the
upper airways was observed at the level of the tongue base and soft palate
by fibroscopy during a Muller manoeuvre (mtb and msp) and ranked on a five
point scale. Sleep indices measured were the mean number of oxygen
desaturations of more than 3% per hour preceded by an apnoea or hypopnoea
of more than 10 s (desaturation index), maximal sleep oxygen desaturation,
baseline arterial oxygen saturation (Sa,O2) and, in the OSA group,
percentage of sleep time with Sa,O2 < 90%. The variables obtained from the
flow-volume curves were the forced vital capacity (FVC), forced expiratory
and inspiratory volume in 1 s (FEV1 and FIV1), peak expiratory and peak
inspiratory flows (PEF and PIF), and maximal flow after expiring 50% of
the FVC (MEF50). The mean of the flow-volume variables, influenced by
upper airway aperture (PEF, FIV1) was significantly greater than
predicted.(ABSTRACT TRUNCATED AT 250 WORDS
Obesity is underestimated using body mass index and waist-hip ratio in long-term adult survivors of childhood cancer
Objective: Obesity, represented by high body mass index (BMI), is a major complication after treatment for childhood cancer. However, it has been shown that high total fat percentage and low lean body mass are more reliable predictors of cardio
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