140s Abstracts Bone Vol. 19, No. 3, Supplement The 7th International Congress of Bone Morphometry September 1996:129S-169s

43 HORMONE REPLACEMENT THERAPY (HRT) PRESERVES CAN- CELLOUS BONE BALANCE BY INHIBITING OSTEOCLASTIC AC- TIVITY: NO EVIDENCE FOR OSTEOBLASTIC STIMULATION. EF Eriksen, B. Langdahl, H. Glerup, A. Vesterby, J. Rungby, M. Kassem. Aarhus Bone and Mineral Research Group, University Department of Endocrinology, Aarhus Amtssygehus. Denmark.

From women participating in a randomized, prospective 2 year study, analyzing the effects of HRT (cyclic estradiol/norethiste-rone (Trisekvensfi)) on bone remodeling, we obtained paired, tetracycline- labeled transiliac bone biopsies. Cancellous bone resorption, formation and structure (star volume) were assessed at the BMU level and tissue level, as shown in the table below (values given as nean+ SEM; * ~~0.05; ** p~o.01, ??** p<g.gg~).

Mer HRT ,N=l5) I Placebo (N=w,

‘req”e”cy I I I I I Marrow *tar mm’ 12.6*2 9 17.2*3 5 12.6*2 6 153*30 “Ol”nw

n conclusion, osteoclastic activity increases with time ir postmenopausal women leading to a progressively more negative bone balance. HRT reverses this process, leading to reduced osteoclastic activity and a preservation of bone balance. No evidence for osteoblastic stimulation was demonstrable, and no significant changes in bone structure were demonstrable

The fractal analysis of osteoporotic cancellow bone struchlre, in cases with vertebral crush fracture, suggests that the spatial structure and bone fine texture is not transformed but the shape and form of individual trabecular spicules is transformed. I. Fazzdari NL, Parkinson M 1996 Fractal dimension and architechlre of trabecular bone. J Patholoav 178:100-105.

44 46 CORRECTION OF BONE LOSS WITH ESTROGEN DEFICIENCY BY 24-EPI-la,25-DIHYDROXYVJTAMIN 4. M.-C. Faugere, Q. Qi. Z. Geng, J. Devane, H.H. Malluche. Div. of Nephrology, Bone & Mineral Metabolism, Univiversity of Kentucky, Lexington, KY (USA), and Elan PLC, Ireland.

Most potent antiosteoporotic agents induce low bone turnover which may affect calcium homcostasis. Preliminary data point to an anabolic effect of 24-epi-la,25dihydroxyvitamin DI (24epi) on bone without suppression of bone turnover. To assess in viva the value of 24-epi on bone loss and bone turnover, 30 dogs were ovariohystereetornized (OX) and 10 dogs were sham-operated (Sham). Six mos. after surgeries, OX dogs were allocated to 3 groups and received for 12 mos either placebo or oral 24-epi at a dose of 75 or 150 ng/kg/d. Sham dogs were given placebo. Blood drawings and iliac crest bone biopsies were done. at 0, 6 and 18mos.

bFGF ENHANCES HUMAN BONE CELL PROLIFERATION IN BONE ALLOGRAFTS IN VITRO. C. Fblschl -, A. Brink, A. Battmann and A. Schulz Institute of Pathology, lDepartment of Surgery, Justus-Liebig-University, _ _ Langhansstr. 10, D-35385 G iessen, Germany

Serum calcium did not change in any group. There was a slight increase in urinary calcium in dogs given 150 n&/d of 24-epi. At mo. 6, a decrease in bone volume was seen in all OX dogs. After 12 mos. of treatment, bone loss was reversed in OX dogs given 24-epi at a dose of 150 g/kg/d (Fig. I), whereas activation frcqueocy was not different from Sham animals (Fig. 2).

Wl ngz

Osteointegration of bone implants is of major importance for the clinical use of bone graft materials. Priming of these materials with growth factors might result in a faster integration of the bone graft into the skeleton and therefore in an accelerated healing process. We evaluated the effect of two different hydroxyapatite based bone implants, one of bovine origin and a synthetical one, loaded with basic fibroblast growth factor @FGF) on normal human bone cells in vitro. Normal human bone cells (femoral heads) were isolated according to the method described by Robey and Termine (1985). The cells were exposed either to bFGF or implant materials alone or after priming of the materials with bFGF. Cell proliferation was assessed using a formazan (MTT) assay. Both, bFGF as well as the tested materials showed a significant increase in bone cell proliferation of about 50% vs untreated control. Priming of the implant materials with bFGF prior to exposure to the cells increased proliferation up to 140% vs control. an additionally examined osteosarcoma cell line showed a significantly lower increase in proliferation. In conclusion, the combination of bone implants and bFGF showed a significant increase in bone cell proliferation in vitro. An enhanced osteointegration of primed implants into the human skeleton might be achieved using the combination tested in these experiments. Robey PG, Termine JD, Calcif Tissue Int 37:453-460, 1985

??Different from Sham, p<O.OS

The data show that long-term oral administration of 24-epi at a dose of 150 ng/kgld reverses tbe bone loss seen after cessation of ovarian function and does not reduce. bone turnover. This ascribes a promising role of 24-cpi as a usehI antiosteoporotic agent.

45 FRACTAL PROPERTIES OF CANCELLOUS BONE IN OSTEOPOROSIS N.L. Fazzdari and I. H. Parkinson. Institute of Medical and Veterinary Science, Adelaide 5000 Australia.

Osteoporosis is characterised by changes in the architecture of cancellow bone. The bone loss associated with osteoporosis occurs through an imbalance of osteoclasts and osteoblasts selectively removing bone and adding bone. This cell activity alters the fractal dimensions of bone

Fractal objects are irregular and have the same degree of irregularity on all scales. Consequently, it is not possible to measure the absolute perimeter or true surface extent of a fractal shape because it changes with the length of the ruler used to make the measurement. A box countiog technique was implemented, with an image analyser, to measure object perimeter at different scales’. The fractal dimension was calculated as the slope of a straight line segment on a plot of log perimeter Vs log box size. The fractal dimension describes the self similarity of the object at different scales.

Real objects have sectional self similarity up to particular or critical resolutions. We report that cancellow bone has multiple sectional self similarity Fractal I relates to bone mineral surface fine texture determmcd by local ostcohlastic and osteoclastic activity. Fractal 2 relates to the form or shape of individual trabecular spicules and fractal 3 relates to the spatial trabecular structure. Osteoporotic patients that have sustained vertebral crush fracture, compared to age matched controls, show no significant statistical group difference for fractal I and 3. On the other hand, fractal 2 for the vertebral fracture group is signiticantly less than the control group (1.15+0.10<1.23~.09) P<O.O02.