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Determination of femur structural properties by geometric and material variables as a function of body weight in rats
A39
Abstracts from Bone Morphology 1992, Lexington, Kentucky
153 IN WV0 EFFECTSOFTHYROID METAB0LlSMINADULTMICE.M.
154 HORMONESON
BONE
Yamamoto,R.,A. Markatos, G.A. Rodan. Department of Bone Biology & Osteoporosis, Merck Research Laboratories, West Point, PA
In vitro studies with fetal mouse long bone rudiments have shown that trtiodothyronine (T3) stimulates bone resorption at high concentrations and inhibits it at low concentrations. To examine whether similar biphasic effects of thyroid hormones are observed in vivo, eight-week old female Swiss-Webster mice (n=6-6 per each group) were made either mildly thyrotoxic by continuous subcutaneous infusion of T3 (3 ug/lOO g BW/day) using an osmotic mini pump or severely thyrotoxic by the addition of 2 ug/ml thyroxine (T4) to the drinking water. The duration of treatment was 3 weeks and all animals were double labelled in vivo with oxytetracycline and calcein. Blood was obtained by cardiac puncture before sacrifice for biochemical evaluation. Femora and tibiae were dissected for ash weight measurements and histomorphometric analysis, respectively. In TB-treated mice serum T3 concentrations were about 2.5fold higher than in control group (2.45 f 0.41 vs. 1.04 rt 0.07 nglml , mean f SEM ), and serum T4 was suppressed. Mean femoral length was significantly (p x 0.05) higher than in controls and there was no difference in ash weight/bone length between the two groups. In T4-treated mice serum T3 concentrations were 5.34 f 0.46 nglml (mean f SEM) and serum T4 was about 3fold higher than in the control. There was no difference in femoral length between TGtreated and control groups, however, ash weight/bone length was significantly (p < 0.05) lower in T6treated mice (1.76 f 0.07 vs. 2.11 f 0.06 mglmm). We conclude that the effects of thyroid hormone on the skeleton are dose-dependent, low concentrations stimulate bone growth whereas high concentrations increase bone resorption and decrease bone mass.
HAINTAINANCE OFBONE
MASS BY PHYSICAL EXERCISE AFTER DISCONTINU-
ATION OF INTERMITTENThPTH(l-34) ADMINISTRATI/DN N.Yamanoto, H.E.Takahashi.T.Tanizawa, R.Fujiboto. K.Tokunaga, T.Hara', S.Tanaka'. H.Hori", T.Uzawa", Department of Orthopaedic Surgery, Department;of Engineering Niigata University'. and Asahi Chemical Industry CO. LTD". Human PTH(l-34) has a marked anabolic effeck on normal and osteopenic rat bone. The purpose of this experisent was to clarify whether the bone mass increased by hPTH in OVK-induced osteopenic rats can be maintained by a daily exerciselwith a treadmill. 11 week-old Sprague-Dawley female rats were injected hPTH(l-34) (30rcg/kgS.C.,3times/week)for 12weeks. Trea@nill exercise were performed for 8 weeks(l5.7m/min,lhour/day,Lidays/week). Bone mineral density(BHD) was measured by DEXACHologic QDR-1000). The experimental design and results of BMD were as follows. 1314 22(Ws after OVX) group 0 1 OBasal control(n=5) (0.260+0.004g/cm~) @Sham(G) e---.vehicle ------. (0.306~0.017) OOVX (6) ----.vehicle ------' (0.282*0.019) ------' (0.308~0.010) @OVX (6) ----,hPTH ----(vehicle ______. no exercise @Sham@) .-. (0.316*0.010) @OVX (8) _e--.vehicle ._____. no exercise .-- (0.290*0.009) (0.288rtO.004) oovx (7) .e--.vehicle --____. treadmill .---__, no exercise --. (0.298*0.008) @OVX (8) ----.hPTH .__W__, treadmill (0.305+0.007) @OVX (7) .-mm.hflH After discontinuationof hPTH. BMD has been reduced in non-exercise rats@ vs.@,p
155
156
EFFECT OF TREADMILL EXERCISE ON THE BONE TURNOVER OF TRABECULAE IN THE PROXIMAL TIBIA OF THE AGED ADULT RAT. J.K. Yeh. M.M. Chen. J.F. Aloia. J.M, Tiernev. S. Snrintz,Winthrop-University Hospital, Mineola, NY 11501, The Health Sciences Center, State University of New York at Stony Brook, Stony Brook, NY, 11794. Exercise has been proposed as a possible way to prevent the bone loss associated with aging. This study examines the effect of exercise on trabecular bone formation and resorption by histomorphometry and metaphyseal bone density by Dual Energy X-ray Densitometry (DEXA). Forty female rats at 14-months of age were divided into exercised (EX) and control (CON) groups. Exercise consisted of running on a flat-bed treadmill, 17 mfmin., 1 hrfday and 5 days/week. Metaphyseal bone density of the tibia of each rat was measured by basal, 9 DEXA at and 16 week periods. Histomorphometric analysis showed that 9 and 16 weeks of exercise suppressed trabecular bone eroded perimeter (30%; 14%, PcO.05) and the ratio of eroded to labeled perimeter (33%; 28%, PcO.05) respectively. A significant increase in the bone formation rate was apparent only after 16 weeks of exercise (mean+S.E. of EX 5.17kO.48 vs CON 3.6520.37 urn/day, P=O.O27). The trabecular area increased and the bone architecture improved (increased trabecular number and decreased trabecular separation) but not significantly to the CON at each time point. The slope of the metaphyseal bone density of each rat was higher in the EX than in the CON group (EX 1.744kO.388 vs CON 0.749kO.345 P=O.037). In mg/cm /week, conclusion, it was demonstrated that the beneficial effect of exercise on aged trabecular bone is primarily in suppressing bone resorption, but also in increasing bone formation.
DETERMINATION OFFEMURSTRUCTURAL PROPER-n S BYGEOMElRlC ANDMATERIAL VARIABLES ASA FUNCTION OFBODYE WEIGHT INRATS. Zan&Xta JR,Capoua RF,MorkleloN, MonruoriE,SanchezTV Ferretti JL. CEMFoC, Rosario; ‘Dr.Gador Labs, and IDIM, Buenos &es. ’Staticbending tests and bone mineral content (BMC) eterminations were performed to femur dipahyses of male and female rats $ 22,84 and 46 weeks of age (n= 1618 and 12 per sex respectively). O$y bone structural properties (fracture toad Wf, stKfness), geometric parameters of bone mass and architecture (diaphyseal volume vol, moment of inertia lx), and material properties concerning tissue stiffness: modulus of etast’ ity E (negative asscciation) and yielding strain Sny (positive ass&ado 1 ) correlated with bw. No relation was found between bw and diiphyseai fall-to-lumen ratio (WLR), material yielding stress (Bsy), orenergy absorptiin abitky per unt bone volume. Bone structural properties (Wf, stiffness) correlated better with geometric (Ix, vol) than with material properties (Sd. E). following similar patterns than those shawn with bw. The BMCper unk volume correlated posittt with E and negatively with Sny but yias not associated to strudural or to other materiai properties. Significant c elatio-nswere found between lx or vol and Bny (both positiie) or E (hot negative), but not with Ssy. Negative and positive associations were res5 ively found between Sny or E and BMC per unk volume. No associatkxr was found, instead, between WLR and any of the material properties1
and architecture.
a BMC-d&&ent propertyregarded as prior in determining bone suppmting ability. No direct associatton might be presu d between BMC and structural properties because of the great influ nce of geometry To= on the latter. The bw should be regarded as a signttcant, abmetric variable for setting the reference point for the feed-back system tflat regulates bone structural properties as a function of invivo mechanical skmulation.
Abstracts from Bone Morphology 1992, Lexington, Kentucky
153 IN WV0 EFFECTSOFTHYROID METAB0LlSMINADULTMICE.M.
154 HORMONESON
BONE
Yamamoto,R.,A. Markatos, G.A. Rodan. Department of Bone Biology & Osteoporosis, Merck Research Laboratories, West Point, PA
In vitro studies with fetal mouse long bone rudiments have shown that trtiodothyronine (T3) stimulates bone resorption at high concentrations and inhibits it at low concentrations. To examine whether similar biphasic effects of thyroid hormones are observed in vivo, eight-week old female Swiss-Webster mice (n=6-6 per each group) were made either mildly thyrotoxic by continuous subcutaneous infusion of T3 (3 ug/lOO g BW/day) using an osmotic mini pump or severely thyrotoxic by the addition of 2 ug/ml thyroxine (T4) to the drinking water. The duration of treatment was 3 weeks and all animals were double labelled in vivo with oxytetracycline and calcein. Blood was obtained by cardiac puncture before sacrifice for biochemical evaluation. Femora and tibiae were dissected for ash weight measurements and histomorphometric analysis, respectively. In TB-treated mice serum T3 concentrations were about 2.5fold higher than in control group (2.45 f 0.41 vs. 1.04 rt 0.07 nglml , mean f SEM ), and serum T4 was suppressed. Mean femoral length was significantly (p x 0.05) higher than in controls and there was no difference in ash weight/bone length between the two groups. In T4-treated mice serum T3 concentrations were 5.34 f 0.46 nglml (mean f SEM) and serum T4 was about 3fold higher than in the control. There was no difference in femoral length between TGtreated and control groups, however, ash weight/bone length was significantly (p < 0.05) lower in T6treated mice (1.76 f 0.07 vs. 2.11 f 0.06 mglmm). We conclude that the effects of thyroid hormone on the skeleton are dose-dependent, low concentrations stimulate bone growth whereas high concentrations increase bone resorption and decrease bone mass.
HAINTAINANCE OFBONE
MASS BY PHYSICAL EXERCISE AFTER DISCONTINU-
ATION OF INTERMITTENThPTH(l-34) ADMINISTRATI/DN N.Yamanoto, H.E.Takahashi.T.Tanizawa, R.Fujiboto. K.Tokunaga, T.Hara', S.Tanaka'. H.Hori", T.Uzawa", Department of Orthopaedic Surgery, Department;of Engineering Niigata University'. and Asahi Chemical Industry CO. LTD". Human PTH(l-34) has a marked anabolic effeck on normal and osteopenic rat bone. The purpose of this experisent was to clarify whether the bone mass increased by hPTH in OVK-induced osteopenic rats can be maintained by a daily exerciselwith a treadmill. 11 week-old Sprague-Dawley female rats were injected hPTH(l-34) (30rcg/kgS.C.,3times/week)for 12weeks. Trea@nill exercise were performed for 8 weeks(l5.7m/min,lhour/day,Lidays/week). Bone mineral density(BHD) was measured by DEXACHologic QDR-1000). The experimental design and results of BMD were as follows. 1314 22(Ws after OVX) group 0 1 OBasal control(n=5) (0.260+0.004g/cm~) @Sham(G) e---.vehicle ------. (0.306~0.017) OOVX (6) ----.vehicle ------' (0.282*0.019) ------' (0.308~0.010) @OVX (6) ----,hPTH ----(vehicle ______. no exercise @Sham@) .-. (0.316*0.010) @OVX (8) _e--.vehicle ._____. no exercise .-- (0.290*0.009) (0.288rtO.004) oovx (7) .e--.vehicle --____. treadmill .---__, no exercise --. (0.298*0.008) @OVX (8) ----.hPTH .__W__, treadmill (0.305+0.007) @OVX (7) .-mm.hflH After discontinuationof hPTH. BMD has been reduced in non-exercise rats@ vs.@,p
155
156
EFFECT OF TREADMILL EXERCISE ON THE BONE TURNOVER OF TRABECULAE IN THE PROXIMAL TIBIA OF THE AGED ADULT RAT. J.K. Yeh. M.M. Chen. J.F. Aloia. J.M, Tiernev. S. Snrintz,Winthrop-University Hospital, Mineola, NY 11501, The Health Sciences Center, State University of New York at Stony Brook, Stony Brook, NY, 11794. Exercise has been proposed as a possible way to prevent the bone loss associated with aging. This study examines the effect of exercise on trabecular bone formation and resorption by histomorphometry and metaphyseal bone density by Dual Energy X-ray Densitometry (DEXA). Forty female rats at 14-months of age were divided into exercised (EX) and control (CON) groups. Exercise consisted of running on a flat-bed treadmill, 17 mfmin., 1 hrfday and 5 days/week. Metaphyseal bone density of the tibia of each rat was measured by basal, 9 DEXA at and 16 week periods. Histomorphometric analysis showed that 9 and 16 weeks of exercise suppressed trabecular bone eroded perimeter (30%; 14%, PcO.05) and the ratio of eroded to labeled perimeter (33%; 28%, PcO.05) respectively. A significant increase in the bone formation rate was apparent only after 16 weeks of exercise (mean+S.E. of EX 5.17kO.48 vs CON 3.6520.37 urn/day, P=O.O27). The trabecular area increased and the bone architecture improved (increased trabecular number and decreased trabecular separation) but not significantly to the CON at each time point. The slope of the metaphyseal bone density of each rat was higher in the EX than in the CON group (EX 1.744kO.388 vs CON 0.749kO.345 P=O.037). In mg/cm /week, conclusion, it was demonstrated that the beneficial effect of exercise on aged trabecular bone is primarily in suppressing bone resorption, but also in increasing bone formation.
DETERMINATION OFFEMURSTRUCTURAL PROPER-n S BYGEOMElRlC ANDMATERIAL VARIABLES ASA FUNCTION OFBODYE WEIGHT INRATS. Zan&Xta JR,Capoua RF,MorkleloN, MonruoriE,SanchezTV Ferretti JL. CEMFoC, Rosario; ‘Dr.Gador Labs, and IDIM, Buenos &es. ’Staticbending tests and bone mineral content (BMC) eterminations were performed to femur dipahyses of male and female rats $ 22,84 and 46 weeks of age (n= 1618 and 12 per sex respectively). O$y bone structural properties (fracture toad Wf, stKfness), geometric parameters of bone mass and architecture (diaphyseal volume vol, moment of inertia lx), and material properties concerning tissue stiffness: modulus of etast’ ity E (negative asscciation) and yielding strain Sny (positive ass&ado 1 ) correlated with bw. No relation was found between bw and diiphyseai fall-to-lumen ratio (WLR), material yielding stress (Bsy), orenergy absorptiin abitky per unt bone volume. Bone structural properties (Wf, stiffness) correlated better with geometric (Ix, vol) than with material properties (Sd. E). following similar patterns than those shawn with bw. The BMCper unk volume correlated posittt with E and negatively with Sny but yias not associated to strudural or to other materiai properties. Significant c elatio-nswere found between lx or vol and Bny (both positiie) or E (hot negative), but not with Ssy. Negative and positive associations were res5 ively found between Sny or E and BMC per unk volume. No associatkxr was found, instead, between WLR and any of the material properties1
and architecture.
a BMC-d&&ent propertyregarded as prior in determining bone suppmting ability. No direct associatton might be presu d between BMC and structural properties because of the great influ nce of geometry To= on the latter. The bw should be regarded as a signttcant, abmetric variable for setting the reference point for the feed-back system tflat regulates bone structural properties as a function of invivo mechanical skmulation.