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Osteocyte-matrix interactions
Bone Vol. 17, No. 3 September 1995:31%331
Abstracts
PlO. Oettocyte-matrix Interactions MH Helfrich, EM Aarden’, PJ Nijweide’, MA Horton** Department of Medicine and Therapeutics, Polwarrh Building, Foresterhill, Aberdeen, AB9 2ZD, ‘Laboratory for Cell Biology and Histology, Uniucrsily of Leiden, The Netherlands and “Imperial Cancer Research Fund, London Osteocyte
(OCY) sensing of mechanical forces on bone may involve modulation of cell-matrix interactions. Here we investigated the interaction of chick OCY with a panel of extracellular matrix proteins. OCY-containing osteoblast (08) suspensions were isolated from 18day old fetal chick calvariae, cells settled onto protein-coated wells of 96 well plates and allowed to adhere for 2 h at 37°C. Adherent OCY were identified by staining with antibody 7.3, after which total cell number (OCY + OB) was determined. Adhesion to chick OB conditioned medium (CCM) was used as standard. OCY adhered well (~50% adhesion compared to CCM) to fibrillar and monomeric type I collagen, osteopontin, vitronectin, fibronectin, thrombospondin and invasin. Lesser adhesion (&I%) was observed on type I collagen, c&zone&in, fibrinogen and pepsin-treated laminin. No adhesion (
Pll.
Effects of long-term hormone replacement therapy on bone
remodelling in postmenopausal women S Vedi, JE Compston Departmenl of Medicine, University of Cambridge School, Addenbrookc’s Hospital, Cambridge
Clinical
The skeletal benefits of hormone replacement therapy (HRT) are well established but its long-term effects on bone remodelling are only partially understood. We have analysed iliac crest biopsies obtained from 25 women, with osteopenia aged 43-72 years before and after treatment with HRT for 18-38 months (mean 23.5). 8pm undecalcified sections were quantitatively assessed using image analysis techniques. Comparison of pre- and post-treatment biopsies revealed significant decreases in osteoid surface (P=O.O02) bone formation rate at tissue level (P=O.O02) and activation frequency (P=O.O4). A small reduction in mean wall width was seen after treatment (38.4.f 6.3 vs 34.4 f 4.1; P=O.O34) whilst the maximum eroded depth decreased from 36.7 to 31.6 pm. These results confirm the importance of reduced bone turnover as a mechanism for preservation of bone mass in women treated with HRT. The observed changes in mean wall width and erosion depth indicate that conventional HRT does not have anabolic effects and that the oestrogen-induced reduction in erosion depth is accompanied by an appropriate decrease in the mean wall width, resulting in an unchanged remodelling balance.
association unknown.
to the risk of osteoporosis
We examined
in later life remains
the relationship
between weight gain in infancy and bone mass during the seventh decade of life in 201 women and 238 men aged 63-73 years for whom detailed birth and childhood records were preserved. Bone mineral was measured at the lumbar spine (LS) and femoral neck (FN) using DXA; osteocalcin was measured on a fasting morning blood sample; DNA from 118 subjects was examined using PCR for the vitamin D receptor RFLP TaqI (coded as Tt where T signifies absence of the site and t signifies presence). There were statistically significant associations between weight at one year and BMC (but not BMD) at the LS (r=O.15, p
P13. 24-hour growth hormone profiles and bone density in elderly men C Fall, P Hindmanh, P Egger, R Eastell, C Cooper MRC Environmen&I Epidemiology Unit, Universily of Southampton, Southampton, Department of Human Metabolism and Clinical Biochemistry, University of Sheffield, Sheffi’eld and Cobbold Laboratories, Middlesex Hospital, London
Growth hormone is an important regulator of bone remodelling, but the relationship between perturbations of the GH axis and the risk of osteoporosis in later life remains uncertain. We therefore studied the GH axis in a group of 19 men selected from the general population, aged 63-73 years. Measurements were made of circulating GH concentrations at 20-minute intervals throughout a 24-hour period, and these were used to calculate peak, trough and median values for GH secretion. IGF-1 and wteocalcin measurements were made on a fasting morning blood sample. Bone mineral density (BMD) at the lumbar spine (IS) and femoral neck (FN) was assessed using DXA. There was a strong negative relationship between BMD at both sites and trough GH concentration (LS r=-0.58, p=O.O09; FN r=-0.56, p=O.O13), but no significant association with peak or median GH levels. There were also negative correlations between osteocalcin and BMD (LS r&.37, p=O.12; FN r=-O.61; p=O.O06) and a positive correlation between trough GH and serum osteocalcin (r=0.43, p=O.O7). After adjusting for weight and height in a regression model, trough GH was negatively, but IGF-1 positively associated with hip BMD. These data suggest that higher basal levels of GH secretion in elderty
lower
men are associated
BMD, independently
with increased
of body
bone turnover
and
size. The discordance
between the effects of GH and IGF-1 on BMD raises the possibility that GH-resistance plays a role in the pathogenesis of male osteoporosis.
Maintenance of the musculoskeletal system in rgeing women by a defined and quantifiable loading regime on the lower limb C Heron, M McDonaugh, AJ El Haj School of Biological Sciences, University of Birmingham, P14.
Fl2. Growth in infancy and bone mass in later life C Cooper, P Egger, C Fall, R EastelI, R Keen, T Spector, D Barker Environmental Epidemiology Unit, University of Southampton, Sourhampron, Department of Human Metabolism and Clinical Biochemistry, Uniwrsiry of Sheffield, MRC
Sheffield London The infant
bone
mass
and
Rheumatology
Unit,
St.
Thomas’
Hospital,
growth trajectory is thought to be a determinant of in young adulthood, but the relevance of this
Birmingham
81.5 27Y
By adapting a system for imposing repetitive strain using a dynanorneter, we have investigated the effects of short duration cyclical loading on the lower limb of ageing women. Ten Caucasian, postmenopausal women between the ages of 65 and 70 carried out a 40 week training regime on one of their limbs with the opposite limb acting as an internal control. Volunteers
323
Abstracts
PlO. Oettocyte-matrix Interactions MH Helfrich, EM Aarden’, PJ Nijweide’, MA Horton** Department of Medicine and Therapeutics, Polwarrh Building, Foresterhill, Aberdeen, AB9 2ZD, ‘Laboratory for Cell Biology and Histology, Uniucrsily of Leiden, The Netherlands and “Imperial Cancer Research Fund, London Osteocyte
(OCY) sensing of mechanical forces on bone may involve modulation of cell-matrix interactions. Here we investigated the interaction of chick OCY with a panel of extracellular matrix proteins. OCY-containing osteoblast (08) suspensions were isolated from 18day old fetal chick calvariae, cells settled onto protein-coated wells of 96 well plates and allowed to adhere for 2 h at 37°C. Adherent OCY were identified by staining with antibody 7.3, after which total cell number (OCY + OB) was determined. Adhesion to chick OB conditioned medium (CCM) was used as standard. OCY adhered well (~50% adhesion compared to CCM) to fibrillar and monomeric type I collagen, osteopontin, vitronectin, fibronectin, thrombospondin and invasin. Lesser adhesion (&I%) was observed on type I collagen, c&zone&in, fibrinogen and pepsin-treated laminin. No adhesion (
Pll.
Effects of long-term hormone replacement therapy on bone
remodelling in postmenopausal women S Vedi, JE Compston Departmenl of Medicine, University of Cambridge School, Addenbrookc’s Hospital, Cambridge
Clinical
The skeletal benefits of hormone replacement therapy (HRT) are well established but its long-term effects on bone remodelling are only partially understood. We have analysed iliac crest biopsies obtained from 25 women, with osteopenia aged 43-72 years before and after treatment with HRT for 18-38 months (mean 23.5). 8pm undecalcified sections were quantitatively assessed using image analysis techniques. Comparison of pre- and post-treatment biopsies revealed significant decreases in osteoid surface (P=O.O02) bone formation rate at tissue level (P=O.O02) and activation frequency (P=O.O4). A small reduction in mean wall width was seen after treatment (38.4.f 6.3 vs 34.4 f 4.1; P=O.O34) whilst the maximum eroded depth decreased from 36.7 to 31.6 pm. These results confirm the importance of reduced bone turnover as a mechanism for preservation of bone mass in women treated with HRT. The observed changes in mean wall width and erosion depth indicate that conventional HRT does not have anabolic effects and that the oestrogen-induced reduction in erosion depth is accompanied by an appropriate decrease in the mean wall width, resulting in an unchanged remodelling balance.
association unknown.
to the risk of osteoporosis
We examined
in later life remains
the relationship
between weight gain in infancy and bone mass during the seventh decade of life in 201 women and 238 men aged 63-73 years for whom detailed birth and childhood records were preserved. Bone mineral was measured at the lumbar spine (LS) and femoral neck (FN) using DXA; osteocalcin was measured on a fasting morning blood sample; DNA from 118 subjects was examined using PCR for the vitamin D receptor RFLP TaqI (coded as Tt where T signifies absence of the site and t signifies presence). There were statistically significant associations between weight at one year and BMC (but not BMD) at the LS (r=O.15, p
P13. 24-hour growth hormone profiles and bone density in elderly men C Fall, P Hindmanh, P Egger, R Eastell, C Cooper MRC Environmen&I Epidemiology Unit, Universily of Southampton, Southampton, Department of Human Metabolism and Clinical Biochemistry, University of Sheffield, Sheffi’eld and Cobbold Laboratories, Middlesex Hospital, London
Growth hormone is an important regulator of bone remodelling, but the relationship between perturbations of the GH axis and the risk of osteoporosis in later life remains uncertain. We therefore studied the GH axis in a group of 19 men selected from the general population, aged 63-73 years. Measurements were made of circulating GH concentrations at 20-minute intervals throughout a 24-hour period, and these were used to calculate peak, trough and median values for GH secretion. IGF-1 and wteocalcin measurements were made on a fasting morning blood sample. Bone mineral density (BMD) at the lumbar spine (IS) and femoral neck (FN) was assessed using DXA. There was a strong negative relationship between BMD at both sites and trough GH concentration (LS r=-0.58, p=O.O09; FN r=-0.56, p=O.O13), but no significant association with peak or median GH levels. There were also negative correlations between osteocalcin and BMD (LS r&.37, p=O.12; FN r=-O.61; p=O.O06) and a positive correlation between trough GH and serum osteocalcin (r=0.43, p=O.O7). After adjusting for weight and height in a regression model, trough GH was negatively, but IGF-1 positively associated with hip BMD. These data suggest that higher basal levels of GH secretion in elderty
lower
men are associated
BMD, independently
with increased
of body
bone turnover
and
size. The discordance
between the effects of GH and IGF-1 on BMD raises the possibility that GH-resistance plays a role in the pathogenesis of male osteoporosis.
Maintenance of the musculoskeletal system in rgeing women by a defined and quantifiable loading regime on the lower limb C Heron, M McDonaugh, AJ El Haj School of Biological Sciences, University of Birmingham, P14.
Fl2. Growth in infancy and bone mass in later life C Cooper, P Egger, C Fall, R EastelI, R Keen, T Spector, D Barker Environmental Epidemiology Unit, University of Southampton, Sourhampron, Department of Human Metabolism and Clinical Biochemistry, Uniwrsiry of Sheffield, MRC
Sheffield London The infant
bone
mass
and
Rheumatology
Unit,
St.
Thomas’
Hospital,
growth trajectory is thought to be a determinant of in young adulthood, but the relevance of this
Birmingham
81.5 27Y
By adapting a system for imposing repetitive strain using a dynanorneter, we have investigated the effects of short duration cyclical loading on the lower limb of ageing women. Ten Caucasian, postmenopausal women between the ages of 65 and 70 carried out a 40 week training regime on one of their limbs with the opposite limb acting as an internal control. Volunteers
323