Abstracts from Bone Morphology 1992, Lexington, Kentucky All

41 SEX-RELATED DIFFERENCES IN MINERAL CONTENT AND MATERIAL, GEOMETRIC AND STRUCTURAL PROPERTlES OF FEMURS FROM AGE- PAIRED FIATS. Ferret0 JL Capoua RF, Sanchez TV, Mondelo N, Montuori E. Zanchetta JR=, Rosario; ‘Dr.Gador’ Labs, and IDIM. Buenos Aires, Argentina.

Low-strain-rate bending tests and bone mineral content (BMC) determinafkms of femur dipahyses of male and female rats of 22 (n= IO,1 O), 34 (18,18) and 48 weeks of age (12,12) were performed to investigate the reason for a noticeable, sex-related biomechanical dimorphism.

Male rats weighed some 50% more than their age-paired females. Bone material showed no sex-related differences in yielding stress and energy absorption ability, but a higher yielding strain and a lower elastic modulus of bone material were found in male than in female femurs. The BMC values were parallel to those of material stVfness (elastic modulus) and inverse to yielding strain data. Diiseal volume and section moment of inertia were higher in mates than in females. No sex-related ditierences were found, however, in wall-to-lumen ratio (a nondirectional indicator of the mean relative wall thickness). Structural (whole-bone) properties (energy absorption ability, strength, stiffness, in decreasing significance order) were higher in male than in female diaphyses but did not diier between sexes after adjustment to a common body weight.

The relatively low stiffness of bone material in maiea seemed to have been compensated in the integrated femurs by an enhancement of bone mass and architectural effk%ncy of tissue distribution throughout the transversal section (moment of inertia), though not by any change in the mere mean relative wall thickness. A feed-back control of the spatial distribution of bone tissue, modulated by the BMC-related material stiffness, is therefore suggested for the assayed model. D#ferencee in biomass setting the reference point for the regulatory mechanism involved should be regarded as significant determinants of the described, sex-related distinction in bone robusticity and structural properties at the organ level of organization.

43 TOTAL SKELETAL HISTOMORPHOMETRY IN A DENNING BLACK BEAR. Timothv FIQy(l Ursine Bone Research Laboratory, Ralph A Nelson. Carle Research Foundation; Sandy n’ Zissimos. University of Caliiornia, Davis. pumaSe. Previous studies of transilial biopsies demonstrated that denninp black bears maintain a high rate of metabolic bone turnover with a high bone formation rate and do not de&p os@opomsis despite months of ina%ity and absence of oral intake. We report here the hiitomorphomeh?z metabolic data from 20 skeletal sites in a denning bear. &&&. A four year old female black bear (Ills a erkanup) was studied. She was taken lrom her natural den and Mintakwd in the dennina p&@o~iistate in acementcuhrertfor 7 weeks. Two libels of tetraqclme HCI (12 mQ&Q) were administered intravenously 7 days apart. Five days later the bear was killed. Serum calcium, phosphorous, urea nitmQm (f3JN) and creatinine wefe measured premortem. At neuopsy bone spedmens were taken from 20 a&l and appendiilar skeletal sites representing weipht-bearing and nonweight-bearing bones as well as cortical and canoallous bone. The specimens were placed in 10% neutral buffered formalin for 48 hours then stored in 70% Etoh. The specimens were stained in ostecchrome stain then embedded in m~methizryhte and processed for nondeminerdbed histomorphomebiC an* whii was conduded on a Leitz epluoresence mimsxqe using a prid retie. Notation was also made of the ;ssociafed fat (F) or hematopoietk (H) mamvr. &t&. Serum chemistries: calcium 8.2 mg/dl, phosphorus 5.0 mgldl. BUN 9 mp”l, creatinine 2.9 mg/dl, urea&atinine ratio 6.7. Histomorphomem (rates riven as pm d ):

BV(%) ES(%) Vertebra 20 1 YY Rib 94 12 1.4 H Iliac crest 14 Cl gstly single label F Humdaph 97 la 5 H/F Raddiaph 97 7 1.4 Oist radius 29 <I mostfy single k&l FF Femdiaph 98 2 13 F Tib diaph 97 z 1.6 Cakane4ls 29 : <I mos@ single label ;

condusions Serum chemistries were consistent with donning physiology. Osteoporosis was not observed in cortical bone, however iliac BV was less than previously reported for three mate dennirtg bears. Cancellous data fmm other sites in nondenning bears have not been oMainedyet. MetaboIicactMtywas~reater incorti~bonethancandlouSmanffastedby more osteoclastic and osteoblastk a%ivity and greater labeling. Single label observed in canceUous bone reflects lower tomovw. This study mnfirms previous findings that bone metabolic ztivity continues at hiQh rates during dennina and further supports the theory that dennina bears have evolved mechanisms to prevent osteoporosis despite months of skeletal in-. Findly, these data, nd data from the other II sites, comprise the first complete hatomorphomslric mip of skeletal metabolism in a bear.

42 QUALITY CONTROL IN HISTOMO PHOMETRY: ASSESSMENT OF QUANTITATIVE BONE 4

UREMENlX LA Fitzoatrick, J Donovan, K Kluge and L Klepper Mayo Clinic and Mayo Foundation, Rochester, MN 55902 USA

Quality of laboratory procedures is an integral pqrt of patient care. Our Bone Hiitomorphometry Laboratory has des$ned methods to evaluate. reproducibility of static and dynamiq parameters of hiitomorphometry. Two methods are described to debermine intra- and inter-observer variability. In one procedure, three

o?

rvers read 35-42 fields per specimen blindly, and the results were corn ared each month. We have completed 18 months of data with the following results (examples limited due to space): Interobserver Variation Mean +SD %CV

CN.BVKV 14.9 0.7 5.3 OS% 53.5 0.9 1.7 NOclEtP 5.0 0.2 4.2 dLPm 34.2 4.4 13.0

In the second exercise, six biopsies (2 low tum+er, 2 “medium” turnover and 2 high turnover as asses& by si@a and activation frequency) were selected. A set of biopsy slides was repared for each biopsy and the reading sequence coded and random f$d for each of 4 readings. A completion timetable is strictly adI+ered to aUow a maximum time of 12 we&s per observer. Raults are expressed as mean + SEM and wefticient of variation was calculated. Sixteen parameters were evaluated; examplea from one read+ are presented: Intraobserver Cn.V OV o.Th. 0c.s Es%BS

Round 1 31.5 2.11 13.1 6.2 14.6 Round 2 29.2 0.90 15.2 10.3 16.8 Round 3 32.9 1.03 15.5 6.5 12.3 Round 4 32.4 1.16 16.4 6.7 11.1

Thresholds were established for each measured paemeter, examples that exceeded threshold were reevaluated, and thd effectiveness of retraining was asesed. Overall, this program improkd the quality of bone biopsy readings in an objective and mmprehenbive manner.

44 EFFECT OF TRANSFORMING GROWTH FACTOR-B ON RAT CALVARIA R.Fujimoto, H.E.Takahashi, T.Tanizawa, N.YanCaoto, K.Tokunaga. Department of Orthopaedic Surgerb. Niigata University School of Medicine, Niigata, Japan.

It has been reported that high dose administration of transforming growth factor-b (TGF-,3) stimulkted local woven bone formation in vivo study using neonatal rat. On the other hand, we found that local subcutaneous injection of low dose(Z0 ng/O.lcc) of TGF-8 for 2 weeks on four-week-old rat calvaria inhibited local lameliar bone fbmation. The purpose of this study is to examine the diffbrence of in vivo effects of TGF-B on rat calvaria by its dose.

In this experiment, four-week-old F344 male rats received a daily subcutaneous injection onto parietal'bone at doses of 0, 2. 20 and 200 ng TGF-B/O.lcc/day for 14 days. All rats were labeled three tines by Calcein(day,O: the day before first injection), tetracycline(day Wand Calceincday 15) and sacrificed at day 16. Each calvariun~was fixed into 70% ethanol and was embedded in methyl methacrylate after prestaining by Villanueva bone stain. Histolbgicai analysis was performed on frontal sections of parietal bone.

In non-treated control and vehicle groups. parietal bone surfaces showed osteoid surface with triple Iinear labels. In 2 ng group, triple labels were always observed. In 20 ng group, initial two labels were observed, but,the width be- tween the second and third became narrower. In 200 ng group. double labels between the first and second dkcreased its widths and the third label was irregular and partially missing.

These findings may suggest that bone fornation is depress- ed by local adninstration of TGF-B on infant rat calvaria.