Osteoblast numbers after calcitonin therapy: a retrospective study of paired biopsies obtained during long-term calcitonin therapy in postmenopausal osteoporosis

The present study is a retrospective examination of osteoblast indices in human iliac crest bone biopsies from a study on the long-term efficacy of calcitonin. Paired baseline and 2-year biopsies were examined from eight control subjects and 10 treated subjects; treated subjects received 100 MRC units synthetic salmon calcitonin (Calcimar, Armour Pharmaceutical Co, Scottsdale, AZ) injected i.m. sub Q at bedtime. Control patients did not receive a placebo injection. All subjects received 400 units vitamin D(2) p.o. q.d. and 1200 mg CaCO(3) p.o. q.d. When the differences in baseline and 2-year values were analyzed, subjects receiving calcitonin showed no decrease compared with control subjects for the fraction of osteoid surface lined by osteoblasts (ObS/OS) (but were in fact significantly greater, P = 0.04). There was no difference from control subjects in the number of osteoblasts/mm bone surface (NOb/BPm), or mean mineral apposition rate (MAR). Since calcitonin is receiving renewed interest for osteoporosis therapy, these data (derived from paired human biopsies) are valuable since they show that no decrease in osteoblast cell number resulted from long-term calcitonin therapy. Results point to the need for renewed investigation concerning the effect of calcitonin on osteoblast-osteoclast interactions.

Hormone replacement therapy prevents osteoclastic hyperactivity: A histomorphometric study in early postmenopausal women

In a randomized, double blind, clinical prospective trial comprising 35 women treated with either hormone replacement therapy (HRT) (cyclic estradiol/norethisterone acetate) or placebo we performed histomorphometric studies on paired bone biopsies obtained before and after 2 years of treatment. Untreated women developed a progressively more negative balance at individual bone multicellular units (BMUs) (i.e., wall thickness-erosion depth) (2.2 +/- 1.7 microm vs. -5.7 +/- 1.4 microm; p < 0.01), while women on HRT displayed preservation of bone balance (2.4 +/- 2.4 microm vs. 2.5 +/- 2.5 microm; NS). No significant differences in wall thickness between the two groups were demonstrable, but the untreated women developed a pronounced increase in erosion depth over 2 years (46.9 +/- 1.8 microm vs. 52.0 +/- 1.9 microm; p < 0.05), while the HRT group revealed no change (47.8 +/- 2.7 microm vs. 44.6 +/- 1.7 microm; NS). Furthermore, the placebo group displayed an increased osteoclastic erosion depth (17.8 +/- 1.6 microm vs. 25.0 +/- 1.7 microm; p < 0.001), compared with unchanged values in the HRT group (20.0 +/- 1.6 microm vs. 16.9 +/- 1.4 microm/day; NS). While the placebo group revealed a slight increase in volume referent resorption rate (35 +/- 8% vs. 38 +/- 8%; NS) the HRT group revealed a pronounced decrease (46 +/- 8% vs. 28 +/- 5%; p < 0.05). No significant changes in marrow star volume (an index of trabecular perforations) were demonstrable in either group. Our results demonstrate that bone remodeling in early postmenopausal women is characterized by progressive osteoclastic hyperactivity, which is reduced by cyclic HRT. This reduction of resorptive activity at the BMU level after HRT seems to precede the reduction in activation frequency demonstrated in previous studies on older postmenopausal women.

Early effects of hormone replacement therapy on bone

Estrogen replacement is currently the preferred therapy for postmenopausal osteoporosis, although its mechanism of action remains poorly understood. Its primary action on bone is generally considered to be antiresorptive, but there is evidence in animals to suggest a stimulatory effect on bone formation. We have now attempted to detect a similar effect in humans by administering hormone replacement therapy (estradiol valerate 2 mg/day and dydrogesterone 5 mg/day given in a continuous, combined manner) to ten postmenopausal women. We carried out histomorphometric analyses of transiliac bone biopsies after quadruple tetracycline labeling, which was commenced before and continued during the first 4 weeks of hormone replacement therapy. Biochemical markers of bone turnover suggested that bone resorption decreased, but no significant effects on histomorphometric parameters of bone formation were detected. We conclude that hormone replacement therapy at the dose given does not stimulate bone formation in the iliac crest as assessed by histomorphometry.

Effects of recombinant human bone morphogenetic protein-2 on differentiation of cells isolated from human bone, muscle, and skin

We investigated the effects of recombinant human BMP-2 (rhBMP-2) on differentiation of cells isolated from human bone, muscle, and skin. Cells isolated from bones of six patients (HBM-1 to HBM-6), muscle from five patients (HM-1 to HM-5), and skin from three patients (HF-1 to HF-3) were used. rhBMP-2 had no effects on proliferation of two HBM cells, but had a stimulatory effect on three HM cell samples. rhBMP-2 stimulated both alkaline phosphatase (ALP) activity in all HBM cells and parathyroid hormone (PTH)-dependent cAMP production in three of the four HBM cell samples, although the magnitudes of these stimulatory effects differed among the cells tested. Although none of the HBM cells examined produced detectable amounts of osteocalcin in the absence of 1,25-(OH)2vitamin D3, they synthesized measurable amounts of osteocalcin in its presence. rhBMP-2 inhibited 1,25-(OH)2vitamin D3-dependent osteocalcin production in all of the HBM cell samples. Transplantation of HBM-6 cells with rhBMP-2 using diffusion chambers into the peritoneal cavity of athymic mice induced formation of cartilage and bone in the diffusion chambers, but neither cartilage nor bone was formed in chambers transplanted without rhBMP-2. rhBMP-2 also stimulated ALP activity in all of the HM and HF cell samples examined and PTH-dependent cAMP production in three of four HM cell samples. rhBMP-2 induced no osteocalcin production in any of the HM or HF cells in the presence of 1,25-(OH)2vitamin D3. rhBMP-2 markedly inhibited myotube formation by all of the HM cell samples. Transplantation of HM-4 cells with rhBMP-2, using diffusion chambers, into athymic mice induced ALP-positive cells in the chambers, but neither cartilage nor bone was observed. These results suggest that rhBMP-2 is a potent stimulator of osteoblast differentiation and bone formation in human cells.

Calcitonin alters bone quality in beagle dogs

Because of its antiresorptive properties, calcitonin is widely used to prevent and treat osteoporosis. A stimulatory effect of calcitonin on osteoblasts has also been reported; however, a recent histologic study points to a negative effect of calcitonin on mineralization of cancellous bone. The present experiment was performed to determine whether the observed histological signs of alterations in mineralization are also observed in cortical bone and whether this results in changes in mechanical properties, mineral densities, or mineral properties of canine bone. Sixteen female adult beagle dogs were randomly allocated to receive either human calcitonin at a dose of 0.25 mg/dog (50 IU, n = 8) or vehicle (mannitol, n = 8) every other day for 16 weeks. At the end of the study, the dogs were euthanized. Both tibiae, L1 and L5 vertebrae, and iliac crest bone samples were excised and defleshed. Torsional mechanical properties of tibial diaphyses and compressive strengths of vertebrae were measured. Bone mineral densities (BMD) of tibiae and vertebrae were measured by using dual-energy X-ray absorptiometry. Ultrastructural mineral characteristics of iliac crest bone were determined by gravimetry and Fourier transform infrared spectroscopy (FTIR). Bone histomorphometry was performed in the cortical envelope of the iliac crest. Tibiae from dogs treated with calcitonin withstood significantly less maximum torque until failure, required less torsional energy to reach the maximum torque, and had less torsional stiffness than the tibiae from dogs treated with vehicle (p < 0.05). Cancellous cores of vertebrae from calcitonin-treated dogs withstood less compressive mechanical loading than did vertebral cores from vehicle-treated animals (p < 0.05). Dogs treated with calcitonin had less BMD of both tibiae and vertebrae than vehicle-treated animals (p < 0.05). Bones from calcitonin-treated dogs had significantly less ash content, which correlated with the lower phosphate-to-amide I (detected by FTIR) and greater carbonate-to-phosphate ratios than did bones from vehicle-treated dogs (p < 0.05). Calcitonin-treated dogs exhibited a decrease in bone formation and mineralization rates and an increase in mineralization lag time. These results point to a negative effect of calcitonin on bone quality. These findings are intriguing and call for further studies addressing whether the observed abnormalities are transient or permanent.

Cortical remodeling following suppression of endogenous estrogen with analogs of gonadotrophin releasing hormone

The effects of estrogen suppression on osteonal remodeling in young women was investigated using transiliac biopsies (eight paired biopsies + four single pre; three single post biopsies) taken before and after treatment for endometriosis (6 months) with analogs of gonadotrophin releasing hormone (GnRH). Estrogen withdrawal increased the proportion of Haversian canals with an eroded surface (106%, p = 0.047), a double label (238%, p = 0.004), osteoid (71%, p = 0.002), and alkaline phosphatase (ALP) 116%, p = 0.043) but not those showing tartrate-resistant acid phosphatase (TRAP) activity (p = 0.25) or a single label (p = 0.30). Estrogen withdrawal increased TRAP activity in individual osteoclasts in canals with diameters greater than 50 microns (p = 0.0089) and also the number of osteons with diameters over 250 microns (p = 0.049). ALP activity in individual osteoblasts was increased but not significantly following treatment (p = 0.051). Wall thickness was significantly correlated with osteon diameter (p < 0.001). In a separate group of patients (four pairs + one post biopsy) on concurrent treatment with tibolone, there was no significant increase in the osteon density, cortical porosity, median canal diameter, or the markers of bone formation and resorption. Enzyme activities and numbers of active canals were also not increased with the concurrent treatment, but there was still an increase in the osteon diameter. As previously shown for cancellous bone, estrogen withdrawal increased cortical bone turnover. We have now shown that resorption depth within Haversian systems was also increased with treatment. The enhanced TRAP activity in individual osteoclasts supports the concept that osteoclasts are more active following estrogen withdrawal in agreement with theoretical arguments advanced previously. Understanding the cellular and biochemical mechanisms responsible for increased depth of osteoclast resorption when estrogen is withdrawn may allow the development of new strategies for preventing postmenopausal bone loss.

The androgenic anabolic steroid nandrolone decanoate prevents osteopenia and inhibits bone turnover in ovariectomized cynomolgus monkeys

We examined the effects of nandrolone decanoate (25 mg im every 3 weeks) on bone mass, serum biomarkers, and bone histomorphometric endpoints in 52 female cynomolgus macaques randomized into four treatment groups: (1) sham-ovariectomized (sham); (2) ovariectomized + placebo for 2 years (ovx); (3) ovx + nandrolone decanoate for 2 years (Nan); and (4) ovx + nandrolone decanoate beginning 1 year after ovx (dNan). Serum alkaline phosphatase (ALP), osteocalcin, and tartrate-resistant acid phosphatase (TRAP) were assayed every 3 months, and X-ray densitometry of the lumbar spine was done every 6 months. Fluorochrome-labeled iliac biopsies collected at baseline and 1 year, and lumbar vertebrae and midshaft femur collected at 2 years, were evaluated histomorphometrically. Body weight increased over 50% with administration of nandrolone. After 2 years, ovx animals had lower spinal BMC and BMD than all other groups. Ovx animals also had higher bone turnover rates than all other groups, as indicated by higher levels of the serum and urine biomarkers, and by at least twofold higher label-based bone formation rates in the femur diaphysis and in both cancellous and cortical bone of the ilium and vertebral bodies. Nandrolone-treated animals had similar serum estradiol levels as the sham animals, presumably due to conversion of endogenous or exogenous androgens. The effects of nandrolone on bone in this experiment are consistent with estradiol action and may be attributable to the increased serum estradiol. Despite >50% higher body weight, nandrolone-treated, ovariectomized animals did not have higher bone mass than sham animals.

Stimulation of endosteal bone formation by local intraosseous application of basic fibroblast growth factor in rats

We investigated the effects of local intraosseous application of basic fibroblast growth factor under physiologic conditions. An aqueous solution containing 0 (vehicle), 25, 100, or 400 micrograms of basic fibroblast growth factor was injected via a needle into the ilium of rats. Two weeks later, bone mineral density of the ilium was significantly increased (P < 0.01) with all three doses, and a dose-effect relationship was apparent. Light microscopy revealed proliferation of undifferentiated mesenchymal cells on the endosteal and trabecular surfaces, as well as apposition of newly formed bone on existing trabeculae. Intraosseous injection of basic fibroblast growth factor may be of use for the treatment of osteoporosis.

The effects of long-term hormone replacement therapy on bone remodeling in postmenopausal women

Hormone replacement therapy prevents menopausal bone loss and reduces the risk of fragility fracture, but its effects on bone remodeling have not been clearly established. We studied the effects of long-term hormone replacement therapy on bone turnover and remodeling balance in 22 postmenopausal women with osteopenia or osteoporosis. Iliac crest biopsies were obtained before and after treatment (mean 23.5 months) after double tetracycline labeling and subjected to histomorphometric analysis. Post-treatment biopsies showed a significant reduction in bone formation rate at tissue level and activation frequency (p = 0.002 and 0.01, respectively). There was also a reduction in mineral appositional rate (p = 0.0002) and osteoid seam width (p = 0.01), but no significant change in mineralization lag time or osteoid maturation period. Wall width showed a significant decrease after treatment (p = 0.03) and there was a consistent trend toward a reduction in resorption cavity dimensions with a statistically significant decrease in the resorption cavity length (p = 0.03). These results confirm the previously reported reduction in bone turnover in postmenopausal women treated with hormone replacement therapy. Post-treatment biopsies also showed a reduction in resorption cavity size and a decrease in wall width, the latter possibly reflecting a compensatory change in response to the reduction in erosion depth. Our data do not provide any evidence that conventional hormone replacement therapy has anabolic effects at the level of the bone remodeling unit and indicate that its beneficial skeletal effects result from suppression of bone turnover and a reduction in the size of resorption cavities.

Strontium distribution and interactions with bone mineral in monkey iliac bone after strontium salt (S 12911) administration

The analysis of the interaction of strontium (Sr) with bone mineral is of interest because a new agent containing Sr (S 12911) has shown positive effects on bone mass in various animal models of osteoporosis and is currently being developed for preventive and curative treatment of postmenopausal osteoporosis. Iliac bone samples were obtained from 20 male monkeys: 4 untreated control animals, 12 animals sacrificed at the end of a 13-week treatment with high dose levels of S 12911 (750, 275, or 100 mg/kg/day orally), and 4 animals sacrificed 6 weeks after the end of a 13-week treatment with S 12911 (750 or 100 mg/kg/day orally). The distribution of Sr was determined and quantified by X-ray microanalysis. Changes at the crystal level were evaluated by X-ray diffraction and Raman microspectrometry. In the control animals, traces of Sr were found to be homogeneously distributed throughout the bone tissue. In the treated monkeys, Sr could only be detected in calcified matrix. In monkeys sacrificed at the end of the treatment, Sr was found to be dose-dependently incorporated into the mineral substance of the compact and cancellous bone. Sr was heterogeneously distributed with three to four times more Sr in new than in old compact bone, and approximately two and a half times more Sr in new than in old cancellous bone. The bone Sr content dramatically decreased in the animals sacrificed 6 weeks after the end of the treatment. Diffraction showed no significant changes in the characteristics of the crystal lattice. Sr appeared to be easily exchangeable from bone mineral and was slightly linked to mature crystals through ionic substitutions. Even at the highest dose level tested, less than 1 calcium ion out of 10 was substituted by 1 Sr ion in each crystal. In conclusion, taken up by bone, Sr was heterogeneously distributed with a higher concentration in new than in old bone but induced no major modifications of the bone mineral (crystallinity, crystal structure) at the crystal level. As a result, a treatment with S 12911 Sr salt should not induce any alteration of bone mineral.

Effects of hormone replacement therapy on cancellous bone microstructure in postmenopausal women

Menopausal bone loss is associated with disruption of cancellous bone architecture which has adverse mechanical effects and is believed to be irreversible. The aim of this study was to examine the effects of long-term hormone replacement therapy on cancellous bone structure in women with postmenopausal osteoporosis. Iliac crest biopsies from 22 women with osteopenia or osteoporosis were obtained before and after hormone replacement therapy (mean duration 23.5 months). Cancellous bone architecture was assessed by strut analysis, trabecular bone pattern factor, and marrow star volume. Post-treatment biopsies showed no significant changes in any of the structural indices assessed. Our results suggest that hormone replacement therapy preserves existing cancellous bone structure but provide no evidence that this treatment is able to reverse structural disruption in women with postmenopausal osteopenia or osteoporosis.

Calcitonin prevents bone loss but decreases osteoblastic activity in ovariohysterectomized beagle dogs

The antiresorptive effects of calcitonin are well documented. Recent in vitro and in vivo evidence points to an anabolic effect of calcitonin on osteoblasts. To assess the value of calcitonin in preventing the rapid and early bone loss after cessation of ovarian function and to investigate its effects on osteoblasts in vivo, 32 dogs were ovariohysterectomized (OHX) and 32 dogs were sham-operated (Sham). After the surgeries, half of the OHX and Sham dogs received every-other-day subcutaneous injections of human calcitonin (0.25 mg/dog/d), and the remaining dogs were given vehicle. Half of the animals had a bone biopsy at week 2 and were euthanized thereafter; the other half of the animals underwent a bone biopsy at month 1 and were euthanized at month 4. Blood drawings were done at baseline and at the time of each bone biopsy. Calcitonin prevented the increase in erosion depth seen in OHX animals and prevented the cancellous bone loss observed at 2 weeks and at 1 and 4 months. Calcitonin did not affect bone volume in Sham dogs. However, treatment with calcitonin induced a decrease in mineralizing surfaces and bone formation rates at the bone surface and cell level and an increase in mineralization lag time in both Sham and OHX animals without significantly affecting osteoblast number. This finding indicates that the negative effect of calcitonin on bone mineralization is not solely the result of a decrease in bone turnover. The data show that calcitonin, because of its antiresorptive effects, can prevent bone loss after cessation of ovarian function. However, short-term treatment with calcitonin does not stimulate osteoblast activity; on the contrary, it exerts a negative effect on osteoblastic bone formation and mineralization. Long-term studies are needed to investigate whether this unwanted effect of calcitonin on osteoblasts in vivo represents a transitory or persistent phenomenon.

Anti-Clostridium difficile bovine immunoglobulin concentrate inhibits cytotoxicity and enterotoxicity of C. difficile toxins

Clostridium difficile diarrhea and colitis result from the actions of bacterial exotoxins on the colonic mucosa. This study examined the ability of hyperimmune bovine colostral antibodies to neutralize the biological effects of these toxins. Anti-C. difficile bovine immunoglobulin concentrate was prepared from the colostral milk of Holstein cows previously immunized with C. difficile toxoids. The anti-C. difficile bovine immunoglobulin concentrate contained high levels of bovine immunoglobulin G specific for C. difficile toxins A and B, as evaluated by enzyme-linked immunosorbent assay. Anti-C. difficile bovine immunoglobulin concentrate neutralized the cytotoxic effects of purified toxin A and toxin B on cultured human fibroblasts, whereas control bovine immunoglobulin concentrate had little toxin-neutralizing activity. Anti-C. difficile bovine immunoglobulin concentrate also blocked the binding of toxin A to its enterocyte receptor and inhibited the enterotoxic effects of C. difficile toxins on the rat ileum, as measured by an increased rat ileal loop weight/length ratio (63% inhibition; P < 0.01), increased mannitol permeability (92% inhibition; P < 0.01), and histologic grading of enteritis (P < 0.01 versus nonimmune bovine immunoglobulin concentrate). Thus, anti-C. difficile bovine immunoglobulin concentrate neutralizes the cytotoxic effects of C. difficile toxins in vitro and inhibits their enterotoxic effects in vivo. This agent may be clinically useful in the prevention and treatment of C. difficile diarrhea and colitis.

Local application of basic fibroblast growth factor into the bone increases bone mass at the applied site in rabbits

The effect of basic fibroblast growth factor (bFGF) applied locally into the bone under physiological conditions was investigated. An aqueous solution containing 0 microgram (vehicle), 100 micrograms or 400 micrograms recombinant human bFGF was percutaneously applied through a needle into the right ilium in rabbit, and the ilia were harvested 4 weeks after the application. Compared with vehicle-treated animals, bone mineral density measured by dualenergy X-ray increased in the 400 micrograms bFGF group. The width of trabeculae in the bFGF-treated groups was greater than in the vehicle group. These results showed that bFGF applied locally into the bone under physiological conditions affected bone formation, and suggested that such an application might have potential for increasing bone.

Histomorphometric and biochemical characterization of bone following acute severe burns in children

Severe burns in adults is associated with an uncoupling of normal remodeling, low bone formation without reduced resorption. The risk of osteopenia that may occur under such circumstances is heightened by our detection in a cross-sectional study of low bone mass in severely burned children. We report here the acute histomorphometric and biochemical response of bone to severe burn injury, as well as bone mass in severely burned children. We enrolled 24 patients ages 5.8 to 17.5 years following burns of 63 +/- 16% (SD) body surface area. Serum and urine were collected weekly until iliac crest bone biopsy was obtained 26 +/- 10 days postburn. Seventeen of 18 patients, including 5 patients receiving growth hormone treatment to accelerate wound healing, failed to take up doxycycline in trabecular bone, and had no detectable osteoblasts at the osteoid seam, while eroded surface was normal and osteoblasts were documented by staining. Thus, bone formation was virtually absent. There was an eightfold elevation in urinary free cortisol excretion and high serum levels of acute phase reactants and interleukin-1 beta and -6. Biochemical markers of bone formation, osteocalcin, and type I procollagen propeptide were low, as were resorptive markers urinary pyridinoline and deoxypyridinoline. However, there was no correlation with resorptive surface. Mean age-related z-score for bone mass was -1.06 +/- 1.05, 40 days postburn. Immobilization and endogenous corticosteroid production may be the main factors responsible for acutely reduced bone formation while inflammatory cytokines may mediate resorption.

Tiludronate: development as an osteoporosis therapy

The clinical development of tiludronate (tiludronic acid, disodium salt) for the treatment of Paget's disease of bone is now being complemented by another clinical trials program to investigate its use in osteoporosis. It is expected that osteoporosis will become a major indication for tiludronate, and this paper describes the trial design and treatment goals that will be employed in these new studies. In studies to assess the incidence of fracture, the primary efficacy end point is the occurrence of vertebral fractures after 3 years of therapy. Secondary end-points include changes in lumbar bone mineral density, spinal deformity index, and height. Changes in biochemical markers and quality of life will also be assessed. Safety evaluations include clinical laboratory parameters, adverse events and, in selected patients, histomorphometry of the iliac crest bone. For the nonfracture studies, the primary efficacy end-point is the effect on bone mineral density after 2 years of therapy. Secondary end-points include vertebral fracture rate, spinal deformity index, and height. Biochemical markers, quality of life, and safety (including bone biopsies in selected patients) will be evaluated as in the fracture studies. The studies are expected to be completed in early 1997, followed by worldwide regulatory applications in late 1997.

Changes in bone mineral density and bone-specific alkaline phosphatase in ovariectomized ewes

An animal model of human osteoporosis which adequately meets many of the criteria needed to test new therapeutic agents is currently unavailable. The old ewe may serve this purpose, as changes in bone remodeling occur within 3 months, and a difference in bone mass has been indicated 6 months after ovariectomy. In the current study, we have measured longitudinal changes in bone mass and bone-specific alkaline phosphatase (BSAP) for six months in 7-9 year old ovariectomized (OVX) ewes. Thirty ewes were divided into three groups: sham-treated (n = 9), OVX (n = 12) and OVX with estrogen implants (OVXE, n = 9). Bone mineral density (BMD) was determined at 0, 3 and 6 months in the vertebrae (L4-L6/L5-L7), calcaneus (CAL) and distal radius (DR) using dual-energy X-ray absorptiometry (DEXA). Bone-Specific Alkaline Phosphatase (Tandem-R Ostase; Hybritech) was determined at monthly intervals. Body weight did not significantly change in any group during treatment compared to sham, although a trend of increasing body weight at 3 and 6 months was apparent in both OVX groups. Luteinizing hormone increased in all OVX ewes as a function of time as expected, demonstrating successful ovariectomies. Uterine weight was significantly increased (p < 0.01) in the OVXE animals compared to Sham and OVX groups. BMD did not change significantly during the 6-month treatment period in the CAL or DR. BMD in the vertebrae (L4-L6/L5-L7) was significantly lower in the OVX group compared to sham (p < 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Human bone tissue formation in diffusion chamber culture in vivo by bone-derived cells and marrow stromal fibroblastic cells

Direct grafts of human cells into immunocompromised or cortisone-treated animals, either alone or within carrier materials, have been used with some success to assess the developmental capability of the grafted cells. However, identification of the donor or host origins of the generated tissue in such direct grafts is essential. In an alternative and extensively used experimental system, cells are cultured within the isolated environments of diffusion chambers, which are surgically implanted in appropriate hosts. This system allows the direct study of the cellular potentials for differentiation as host tissues are excluded. In the present study, human osteoprogenitor cell populations derived from trabecular bone explants or marrow suspensions of 3 patients (2 females aged 14 years and 1 male aged 27 years) were cultured in the absence or the continuous presence of dexamethasone (10 nmol/L). Cells were impregnated into porous hydroxyapatite ceramics before subcutaneous implantation, or placed within diffusion chambers before intraperitoneal implantation, in athymic mice. All subcutaneous implants of cells in ceramic showed morphological evidence for the formation of bone tissue. In the diffusion chambers it was found that both marrow- and bone-derived fibroblastic cells cultured in the absence of dexamethasone generally produced fibrous tissue only. When cultured in the continuous presence of dexamethasone (10 nmol/L), these cell populations produced similar osteogenic tissues with active osteoblasts, wide osteoid seams, and mineralized tissue, with cartilage toward the interior of the chamber. These results validate the diffusion chamber as an experimental system to study human osteogenesis using appropriately primed cell populations.

The anabolic effect of human PTH (1-34) on bone formation is blunted when bone resorption is inhibited by the bisphosphonate tiludronate--is activated resorption a prerequisite for the in vivo effect of PTH on formation in a remodeling system?

Parathyroid hormone (PTH) and its (1-34) fragment are stimulators of bone turnover that have an anabolic effect increasing trabecular bone mass when administered intermittently by daily subcutaneous injections. Its clinical use in osteoporosis, however, has been limited by the concomitant increased bone resorption and deleterious effect on cortical bone. To evaluate if a treatment combining PTH and a potent inhibitor of bone resorption would retain the anabolic effect of PTH without increasing bone resorption, we analyzed the effects of PTH (1-34) (500 IU/d) with or without the bisphosphonate tiludronate (1 mg/kg per day) for 3 months on biochemical and histological indices of bone turnover in old female sheep, an animal model which has a slow bone remodeling activity that resembles the one of elderly women. As expected, PTH (1-34) induced a significant increase of urinary pyridinoline and hydroxyproline (reflecting bone resorption), and of serum osteocalcin and alkaline phosphatase (reflecting bone formation), that were consistent with an increase of resorption and tetracycline-based formation of bone measured on iliac crest biopsy. In contrast, all biochemical and histological indices of bone turnover were decreased in sheep receiving tiludronate, a potent inhibitor of bone resorption. Surprisingly, in the combined therapy group, biochemical and histological indices of both resorption and formation did not differ from the control groups. Thus, the model of old sheep, which closely resembles the situation in old human, shows that the anabolic effect of PTH on bone is not maintained when PTH is coadministered with a bisphosphonate, in marked contrast to results noted in the growing rat.(ABSTRACT TRUNCATED AT 250 WORDS)

A histomorphometric study of bone changes in thyroid dysfunction in rats

Clinical studies in thyrotoxicosis reveal a state of high bone turnover leading, eventually, to osteoporosis. Recently there has been concern that thyroxine (T4) treatment may have a similar effect on bone. Rat models have been used to study the effects of T4 on bone, but the majority of studies have looked at the effects of T4 after only 3 weeks of treatment. The aim of this study was to evaluate histomorphometric changes in rats after 12 weeks of thyroxine overtreatment or 12 weeks of hypothyroidism compared with untreated control animals. Animals received either T4 200 micrograms/kg per day, 0.1% propylthiouracil, or vehicle for 12 weeks. Tetracycline was administered 1 week and 3 weeks prior to killing. Iliac crest bone was used for histomorphometry. Serum T4 measurements (taken at killing) confirmed hyper- and hypothyroidism in the appropriate animal groups (between group difference p < 0.001 by ANOVA). In hyperthyroid animals there was an increase in mineral apposition rate (MAR; 0.94 vs. 0.59 microns/day, p < 0.001) and mineral formation rate (MFR/BS; 0.24 vs. 0.12 x 10(-2) micron3/micron2 per day, p < 0.001) and a slight increase in eroded surfaces (ES/BS%; 1.54 vs. 1.36, p < 0.05) compared with controls, consistent with previous in vitro and in vivo observations. In hypothyroid rats there was a marked reduction in osteoid surfaces (OS/BS%; 1.7 vs. 24.8, p < 0.001) and MAR (0.3 vs. 0.59 micrograms/day, p < 0.001), a reduction in ES/BS% (0.51 vs. 1.36, p < 0.05), and an increase in cancellous bone volume (BV/TV%; 30.29 vs. 19.6, p < 0.05), suggesting that thyroid hormones are a requirement for normal bone turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

[Loss of trabecular bone strength and bone quality after 5 years of fluoride therapy for osteoporosis]

In order to evaluate the effect of sodium fluoride (NaF) on bone biomechanical competence, iliac crest biopsies were taken before and after one year of treatment in 12 osteoporotic patients, and before and after five years of treatment in 14 patients. Bone fluoride content had increased significantly after both one and five years of treatment, indicating that the administered fluoride had been ingested. After one year of treatment, no difference was observed in iliac crest trabecular bone ash content. A general trend for decreased bone strength and bone quality was observed, but this was insignificant. After five years of fluoride treatment, an insignificant decrease in iliac crest trabecular bone ash content was observed. A significant reduction of 45% was found in trabecular bone strength (p < 0.05), and an even more pronounced reduction of 58% was found in trabecular bone quality (p < 0.01). The results of this study indicate that long-term administration of sodium fluoride may be detrimental to bone quality, at least as measured in non-loaded iliac crest trabecular bone.

The effects of risedronate on canine cancellous bone remodeling: three-dimensional kinetic reconstruction of the remodeling site

To investigate the dose-dependent effects of risedronate on cancellous bone remodeling, adult female beagle dogs were treated with either placebo, 0.1, 0.5, or 2.5 mg/kg/day of risedronate orally in an intermittent cyclic regimen (7 days on 21 days off), repeated three times. Iliac cancellous bone samples were subjected to histomorphometric analysis and three-dimensional (3-D) kinetic reconstruction of the remodeling site was performed. In the 0.1 mg/kg dose group, resorption and activation indices were no different from the placebo group. However, wall thickness was increased resulting in a positive bone balance at the level of the remodeling unit. In the 0.5 and 2.5 mg/kg dose groups, a dose-dependent reduction in activation frequency and tissue level bone formation was observed. Resorption rates were also significantly decreased, 60% and 80% for the 0.5- and 2.5-mg/kg groups, respectively. An approximate 25% reduction in final erosion depth was noted in both these groups. Analyses of the growth curves of the bone packet confirmed that the kinetics of the growth of a completed packet were different in the 0.5- and 2.5-mg/kg dose groups compared with placebo. These changes were associated with a significant increase in the final wall thickness in both groups indicating no net impairment of osteoblast function. These increases in wall thickness in combination with the reductions in final erosion depth in the 0.5 and 2.5 mg/kg groups resulted in a significant dose-dependent positive bone balance. This pharmacological profile suggests that risedronate may be of therapeutic utility in the treatment of metabolic bone diseases where reductions in activation frequency and resorptive cell activity at the level of the remodeling unit are a therapeutic goal.

Effects of 24R,25-dihydroxyvitamin D3 in combination with 1 alpha-hydroxyvitamin D3 in predialysis renal insufficiency: biochemistry and histomorphometry of cancellous bone

The effect of combined administration of 24R,25-dihydroxyvitamin D3 (24,25-(OH)2D3) and 1 alpha-hydroxyvitamin D3 (1 alpha-(OH)D3) was studied in 24 non-dialyzed patients with chronic renal insufficiency (CRI), matched pairwise as to age, sex, and creatinine clearance (Cr.cl). Low Ca intake had been supplemented beforehand. Then, 1 alpha-(OH)D3 (mean dose 0.55 micrograms daily) was given orally to all patients for 3 months (T0 to T3). Subsequently, patients were assigned randomly to 6 months further treatment either with 1 alpha-(OH)D3 alone (Group A) or with 1 alpha-(OH)D3 plus a high dosage of 24,25-(OH)2D3 (50 micrograms orally, twice weekly) (Group B). Histomorphometry was performed at T0, T3, and T9. In both groups iPTH was equally suppressed, into the lower normal range. Whereas in Group A, serum Ca rose steadily and Cr.cl declined, in Group B both parameters levelled off between T6 and T9. At T9, in Group A the elevated resorption and osteoid indices had normalized markedly, but osteoblasts (Ob.Pm) and mineralizing boundaries (M.Bd) were depressed considerably between T3 and T9. In contrast, in Group B, preservation of Ob.Pm and improved mineralizing activity were observed (M.Bd at T9 > T3 > T0). Resorption indices hardly changed. In the patients with high Ob.Pm at T0, cancellous bone area increased significantly. This was not observed in Group A. Thus, in Group B, osteoblast recruitment appeared maintained and M.Bd appeared normalized. Decline of remodeling toward an adynamic state with an increased risk of hypercalcemia appeared prevented.

The effects of gonadotrophin-releasing hormone agonists on iliac crest cancellous bone structure in women with endometriosis

The administration of gonadotrophin-releasing hormone (GnRH) analogs to premenopausal women causes hypoestrogenism and bone loss, but the effects on cancellous microstructure have not been determined. In this study we have assessed bone structure in transiliac biopsies obtained from women before and after treatment for endometriosis with GnRH analogs. Twenty-one premenopausal women were studied, paired biopsies being obtained in 13; five women received both GnRH analogs and Org OD 14 (Tibolone, Livial). Comparison of pre- and post-treatment biopsies in women treated only with GnRH analogs showed a reduction in indices related to connectivity (node-to-terminus ratio, node-to-loop strut length, p < 0.02) and increase in inversely related indices (terminus-to-terminus and node-to-terminus strut length, p < 0.03). No significant changes were seen in any of the structural indices in women receiving both GnRH and Org OD 14 therapy. Activation frequency and bone formation rate at tissue level increased in women treated with GnRH agonists alone, although this change was not statistically significant. Our results suggest that bone loss induced by GnRH analogs may be associated with adverse effects on cancellous microstructure which are unlikely to be reversed following cessation of therapy. Concurrent treatment with Org OD 14 appears to prevent these changes.

Skeletal response to recombinant human growth hormone (rhGH) in children treated with long-term corticosteroids

Corticosteroid therapy causes osteopenia and growth retardation in children; such changes are associated with diminished rates of bone formation and turnover. Since growth hormone activates bone remodeling, the biochemical and skeletal responses to rhGH were evaluated in four pediatric patients, aged 12.8 +/- 3 years, with long-term corticosteroid use (5 +/- 2 years). Recombinant human growth hormone (rhGH), 0.125 mg/kg, was given 3 times/week by subcutaneous injection for 12 months. Iliac crest bone biopsies were obtained after double tetracycline labeling before and at the end of rhGH therapy; serum levels of calcium, phosphorus, alkaline phosphatase, parathyroid hormone (intact), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D3, osteocalcin (BGP), and insulin-like growth factor-1 (IGF-1) were measured every 3 months during the treatment period. The average dose of prednisone was 0.24 +/- 0.05 mg/kg/day initially, and this did not change during the study. Serum calcium, phosphorus, alkaline phosphatase, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D3, and BGP were unchanged during the rhGH therapy, but the serum IGF-1 level increased by 71%, p < 0.01. Eroded bone perimeter and cancellous bone area did not change significantly during rhGH therapy. Bone formation rates rose from 423 +/- 475 to 781 +/- 407 microns2/mm2/day, p < 0.05, and the length of double tetracycline-labeled bone perimeter increased by 85%, p < 0.05. The bone formation rate in the growth hormone group exceeded the values of an age-matched reference group (14.3 +/- 3 years), 780 +/- 407 microns2/mm2/day versus 411 +/- 479 microns2/mm2/day, p < 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of tiludronate on bone loss in paraplegic patients

Immobilization secondary to spinal cord injury is associated with a marked and rapid atrophy of trabecular bone (disuse osteoporosis). This is due to an early increase of osteoclastic bone resorption associated with a pronounced decreased osteoblastic bone formation. Bisphosphonates are antiosteoclastic compounds and they have been effective in preventing disuse osteoporosis. However, some of them also depress osteoblastic activity and may impair the mineralization process. Tiludronate was shown effective in reducing bone resorption in several metabolic bone diseases without inducing mineralization defects. Twenty paraplegic patients (6 females and 14 males) were randomly assigned to three groups: 6 patients entered the placebo group; 7 patients received tiludronate 200 mg/day; and 7 received 400 mg/day. Histomorphometric analysis was performed on transiliac bone biopsies before and after 3 months treatment. An insignificant decrease of bone volume was observed in the placebo group and the 200 mg group. In patients receiving 400 mg/day, a slight increase was noted. Osteoid parameters changed nonsignificantly in three groups although the 400 mg group exhibited a slight tendency to decrease osteoid volume and thickness. Eroded surfaces increased in all groups. The number of osteoclasts (identified histochemically by TRAP staining) increased in the placebo group but decreased in groups receiving tiludronate. Tiludronate appears effective in reducing bone resorption without impairing bone formation in a manner that preserved bone mass and bone cell coupling.

Effect of slow-release sodium fluoride on cancellous bone histology and connectivity in osteoporosis

We have previously demonstrated that a treatment regimen of slow-release sodium fluoride (SRNaF) and continuous calcium citrate increases lumbar bone mass, improves cancellous bone material quality, and significantly reduces vertebral fracture rate in osteoporotic patients. In order to assess whether such treatment also improves trabecular structure, we quantitated cancellous bone connectivity before and following 2 years of therapy with SRNaF in 23 patients with osteoporosis and vertebral fractures. In addition, we performed bone histomorphometry on the same sections used for connectivity measurements. There was a significant increase in L2-L4 bone mineral density during therapy (0.827 +/- 0.176 g/cm2 SD to 0.872 +/- 0.166, p = 0.0004). Significant histomorphometric changes were represented by increases in mineral apposition rate (0.6 +/- 0.4 microns/d to 1.1 +/- 0.7, p = 0.0078) and adjusted apposition rate (0.4 +/- 0.3 microns/d to 0.6 +/- 0.4, p = 0.016). On the other hand, trabecular spacing significantly declined (from 1375 +/- 878 microns to 1052 +/- 541, p = 0.05). Two-dimensional quantitation of trabecular struts on iliac crest histological sections disclosed significant increases in mean node number per mm2 of cancellous tissue area (0.22 +/- 0.12 vs. 0.39 +/- 0.27, p = 0.0077), the mean node to free-end ratio (0.23 +/- 0.21 vs. 0.41 +/- 0.46, p < 0.05), and in the mean node to node strut length per mm2 of cancellous area (0.098 +/- 0.101 vs. 0.212 +/- 0.183, p < 0.01). There were no significant changes in any of the measurements associated with free-end number or free-end to free-end strut length.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal bone mineralization after fluoride treatment in osteoporosis: a small-angle x-ray-scattering study

Sodium fluoride treatment of osteoporosis is known to stimulate bone formation and to increase bone mass, but recent clinical trials failed to prove its antifracture effectiveness. The formation of bone with abnormal structure and, therefore, increased fragility is discussed as a possible explanation. Until now, however, exact information on the mineral structure of osteoporotic bone after fluoride treatment has been lacking. Bone biopsies were taken from three patients with postmenopausal osteoporosis before and after fluoride treatment (60 mg NaF/day for 1-2 years), from one patient with iatrogenic fluorosis, as well as from three normal controls. The mineral in these samples was investigated by a combination of backscattered electron imaging and small-angle x-ray scattering. Depending on the total dose of fluoride, an increasing amount of new bone is laid down on the surface of preexisting trabeculae. Its mineral structure is identical to that of heavy fluorosis and is characterized by the presence of additional large crystals, presumably located outside the collagen fibrils. These large crystals, which are not present in the controls or in osteoporotic bone before fluoride treatment, contribute to increase the mineral density without significantly improving the biomechanical properties of the bone. The possible success of fluoride treatment depends not only on the amount of newly formed bone but also on the rate of bone turnover. Indeed, as soon as significant amounts of fluoride are present, bone turnover leads to the replacement of old (normal) bone by new (pathologically mineralized) bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Marked decrease in trabecular bone quality after five years of sodium fluoride therapy--assessed by biomechanical testing of iliac crest bone biopsies in osteoporotic patients

Sodium fluoride has for more than 2 decades been a commonly used therapeutic agent for established osteoporosis because of a repeatedly documented anabolic effect on trabecular bone mass. Recently, however, three controlled trials have failed to demonstrate any therapeutic advantage of NaF over placebo with respect to vertebral fracture rate. Also, there have been several reports of an increased incidence of nonvertebral fractures during fluoride administration. Thus, the efficacy of fluoride therapy remains a controversial issue. The aim of this longitudinal study was to investigate the effect of sodium fluoride (40-60 mg per day), calcium (45 mmol), and vitamin D2 (18,000 IU) on trabecular bone strength, assessed before and after 1 or 5 years of treatment for osteoporosis. Iliac crest biopsies were taken before and after 1 year of treatment in 12 patients, and before and after 5 years of treatment in 14 patients. Measurements were made of biomechanical competence, ash content, and bone fluoride content, and bone strength parameters were normalized for ash content, thereby obtaining a measure of trabecular bone quality. Bone fluoride content was significantly increased after both 1 and 5 years of treatment, indicating that the administered fluoride had been ingested. After 1 year of treatment, no difference was observed in iliac crest trabecular bone ash content. A general trend for decreased bone strength and bone quality was observed, but this was insignificant. After 5 years of fluoride treatment, an insignificant decrease in iliac crest trabecular bone ash content was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of long-term tamoxifen therapy on cancellous bone remodeling and structure in women with breast cancer

The effects of long-term tamoxifen therapy on bone remodeling were studied in 41 women with breast cancer, 22 treated with tamoxifen for a minimum of 15 months (mean 33) and 19 untreated. Transiliac crest bone biopsies were obtained and a comprehensive histomorphometric analysis performed using a semiautomatic image analysis system. There were no statistically significant differences between the two groups in bone area, osteoid perimeter and area, or osteoid width. Mineral appositional rate, adjusted appositional rate, and mineralization lag time were also similar in the two groups; however, tissue-based bone formation rate was significantly lower in the tamoxifen-treated women (p = 0.05) and the remodeling period significantly longer (p < 0.05). Mean and maximum resorption cavity depth and cavity area were significantly reduced in the tamoxifen-treated patients compared to the untreated patients (p < 0.01, p < 0.01, and p < 0.03, respectively). Calculated and directly measured indices of cancellous bone structure were similar in the two groups, although the data indicated a trend toward greater connectedness in the tamoxifen-treated group. These data indicate that tamoxifen does not exert an antiestrogenic effect on bone remodeling in the human and are consistent with a weak estrogenic effect.

The effect of systemic antibiotic and antibiotic-impregnated polymethylmethacrylate beads on the bacterial clearance in wounds containing contaminated dead bone

A dorsal muscular wound model was used in 40 New Zealand White rabbits to study the effect of systemic and local antibiotics on the bacterial clearance of contaminated dead bone. Devitalized iliac crest bone preincubated with Staphylococcus aureus was implanted in each deep muscular wound with or without tobramycin-impregnated polymethylmethacrylate beads. Either systemic tobramycin or cefazolin was administered for 7 days. Animals were sacrificed at 7 and 14 days. The wounds containing tobramycin beads had significantly fewer bacteria than those without antibiotic beads (2.0 x 10(2) versus 1.3 x 10(6); p < 0.008). The reduction in bacteria due to the tobramycin beads did not differ significantly with respect to the concurrent systemic antibiotics or to the duration of incubation. We conclude that tobramycin-impregnated beads are effective in reducing bacterial count in contaminated bony wounds treated with systemic antibiotics. Furthermore, the bactericidal effect of the antibiotic beads is independent of and additive to the systemic antibiotic delivered to the wounds by well-perfused muscles.

[Bone histomorphometric study of the ilium in psychiatric patients with longterm administration of anti-psychiatric drugs]

Histomorphometric studies were performed on biopsies of the spongiosa from the iliac crest of patients with fracture who had been taking medication for a psychiatric condition. The biopsy had been performed in 30 individuals, 10 of which were males and 20 females, ages ranging from 23 to 63 years, and from 21 to 75 respectively. Twenty healthy individuals were use as control. All anti-psychiatric drugs in this study have been calculated in terms of chlorpromazine (CPZ). The purpose of the study and intraoperative biopsy had been explained to the patients and their agreements were obtained before the surgery. The undecalcified specimen made from the iliac crest were studied using a semiautomatic image analyzer. In the result of this study, there was decrease in the bone volume (BV/TV), the osteoid surface (OS/BS), and the eroded surface (ES/BS) in the affected subjects compared to the controlled group. However, there was increase in the relative osteoid volume (OV/BV) among the subjects who had had a psychiatric condition for 21 years or more and taking more than 500 x 10(4) mg of CPZ. There was no significant difference in the mineral apposition rate (MAR) between the dosage of CPZ and periods of intake; however the MAR was elevated in the affected group as compared to the controlled group. In conclusion, prolonged administration of CPZ may increase the volume of osteoid and disturb the calcification.

[Effect of long term treatment with prednisone on remodeling of cancellous and cortical bone in dogs]

The effect of 7 month prednisone administration on cancellous and compact bone remodeling in dogs was evaluated by means of histomorphometric and tetracycline labeling methods. It was found that treatment with prednisone resulted in decrease of bone mass which was caused by increased bone resorption as well as considerable diminution of bone formation. In the iliac bone those were manifested by increase in resorption of trabecular surface, decrease in osteoid surface, and reduction in the osteoid thickness, indicating, with a simultaneous decrease in mineralization rate, slowing down of the appositional rate of newly formed bone tissue. In the rib cortical bone treatment with prednisone resulted in increase of the resorption sites together with decrease of the formation sites and tetracycline-labeled osteons. Reduction in the osteoid thickness as well as in the mineralization rate was also observed. The changes of bone remodeling parameters due to prednisone, although proceeding in the same direction in both types of bone tissue, were more marked in the spongy bone than in the compact bone.

24,25-dihydroxy vitamin D3 treatment inhibits parathyroid-stimulated adenylate cyclase in iliac crest biopsies from uremic patients

Renal osteodystrophy with increased bone resorption is a major clinical problem in patients with chronic renal failure. Previous reports have shown that treatment with 24,25-dihydroxy vitamin D3 (24,25(OH)2D3) may result in decreased bone resorption. The present study addresses basic mechanisms for the action of 24,25(OH)2D3 in bone of patients with elevated serum parathyroid hormone (PTH) levels due to chronic renal disease. Twenty-four patients 56 +/- 17 years old (mean +/- SE) with chronic kidney disease in the predialytic state (serum creatinine > 150 mumol/l) and elevated serum midregion PTH > 1.2 micrograms/l were randomly assigned to oral treatment with either 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) (0.25-0.50 microgram/day), 24,25(OH)2D3 (daily dose of 15 micrograms), or a combination of the two vitamin D3 analogs. The control group received calcium carbonate (maximal dosage of 1 g x 3). Selected variables in serum and urine as well as hormone sensitive adenylate cyclase (AC) in iliac crest biopsies were assessed before treatment and during follow-up after two and six months. Serum levels of 1,25(OH)2D3 and 24,25(OH)2D3 were significantly (P < 0.05) increased after two and six months in the respective treatment groups. Net bone PTH-enhanced AC (PTH-AC) fell abruptly (P < 0.01) after two months of treatment and was nearly abolished (P < 0.01) after six months with 24,25(OH)2D3 given alone or in combination with 1,25(OH)2D3. An inverse relationship (r = -0.57, P < 0.05, n = 48) between net PTH-AC in bone and serum levels of 24,25(OH)2D3 was demonstrated. In all groups, serum total calcium (s-Ca) was maintained within normal range.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in bone histomorphometry after long-term treatment with intermittent, cyclic etidronate for postmenopausal osteoporosis

Intermittent, cyclic etidronate therapy (400 mg/day for 2 weeks followed by 13 weeks free from study drug administration) resulted in a significant increase in lumbar bone mineral content and a significant decrease in the rate of new vertebral fractures in patients with postmenopausal osteoporosis. To investigate the effect of the treatment on bone histomorphometry, transiliac crest bone biopsy samples were obtained in this study before treatment and after 60 and 150 weeks of treatment with either intermittent, cyclic etidronate (n = 33) or placebo (n = 33). After 60 weeks of etidronate therapy, significant decreases in activation frequency (from 0.55 to 0.09 year,-1 P < 0.01) and resorption depth (from 53.2 to 37.8 microns, P < 0.05) were observed, leading to a positive balance per remodeling cycle. In the placebo group, no significant changes were seen. The 150 week bone biopsy samples were suboptimal for analysis, probably as a result of a regional acceleratory phenomenon. Our results suggest that, as a result of reductions in both activation frequency and resorption depth, intermittent, cyclic etidronate therapy may protect the trabecular network against fortuitous perforations and thereby maintain the strength of the bony tissue.

Morphometric changes in growth of the rat pelvis after papain administration

The proteolytic enzyme, papain, was given systematically to evaluate the short- and long-term effects of inhibition of endochondral bone formation on pelvic growth, with emphasis on the innominate bone. Ninety-eight Lewis-strain male rats, used concurrently for craniofacial growth studies, were divided into two groups. Thirty rats from Group I (n = 48) received 2% crude papain i.p. daily from 25-40 days-of-age and were euthanized at 40, 54, and 70 days-of-age. Thirty-five rats from Group II (n = 50) were given papain at the same dose from 25-70 days-of-age and were euthanized at 26, 40, 54, 70, and 120 days. The remaining animals in both groups were the controls. Standardized dorsoventral pelvic radiographs were taken of all 98 animals. Ten linear dimensions were measured on each and the data evaluated statistically. A reduction both in size and rate of growth of the bony pelvis was found. All the anteroposterior and most of the transverse pelvic dimensions were significantly shorter, to a greater extent in the prolonged papain group. Bi-ischial width was increased, perhaps to compensate for pelvic shortening and to accommodate the pelvic contents. The findings may contribute to our better understanding of abnormal endochondral bone growth in the pelvis.

Osseous regeneration in the presence of four common hemostatic agents

The iliac crest is a common site for bone procurement in oral and maxillofacial surgery. The goal of this study was to evaluate the potential for bone regeneration in the presence of four common hemostatic agents in a manner that parallels iliac bone procurement in humans. The agents evaluated were 1) Avitene (microfibrillar collagen; Medchem Products, Inc, Woburn, MA); 2) bone wax (beeswax with isopropyl palmitate; Ethicon, Inc, Somerville, NJ); 3) Gelfoam (absorbable gelatin sponge; The Upjohn Company, Kalamazoo, MI); and 4) Surgicel (oxidized regenerated cellulose; Johnson & Johnson Products, Inc, Patient Care Division, New Brunswick, NJ). Five surgical defects in each of four dogs were created for placement of the four materials; one defect served as an empty control site. The dogs were then allowed to heal over a 2-month period. Radiographic and histologic examination showed new bone formation in the presence of Avitene, Surgicel, and Gelfoam. Residual material incorporated in bone, without foreign-body response, was noted in the Avitene and Gelfoam sites. Bone wax, however, showed an intense foreign-body reaction, characterized by giant cells, plasma cells, fibrous granulation tissue, and lack of bone reformation. On the basis of these initial findings, it was concluded that Surgicel, Avitene, and Gelfoam may be adequate hemostatic agents for use in iliac bone procurement, whereas the use of bone wax appears to be contraindicated.

Regulation of bone turnover and prevention of bone atrophy in ovariectomized beagle dogs by the administration of 24R,25(OH)2D3

In order to determine whether the administration of 24R,25(OH)2D3 had any beneficial effect on the regulation of bone turnover and the prevention of bone atrophy, we examined beagles for 31 months after ovariectomy (OVX). Fourteen beagle dogs (8.54 +/- 1.22 kg body wt-b.w.) were divided into four groups. Group 1 (n = 3) was the sham, and Group 2 (n = 3) served as the OVX control. In Group 3 (n = 4) and Group 4 (n = 4), 24,25-dihydroxyvitamin D3(24R,25(OH)2D3) was given daily at dose levels of 2 and 10 mcg/kg B.W., respectively. In Group 4, the dose level was increased to 100 mcg/kg by 17 months. During the experiments, urinary hydroxyproline (U-HPr), serum chemistry, serum bone gla-protein (BGP), and vitamin D metabolite levels were monitored. At the end of the experiment, bone mineral content (BMC) in the 6th and 7th lumbar vertebrae and right femur was determined by single photon absorptiometry. The left iliac bone sample was obtained after tetracycline labeling, and undecalcified sections were observed. In Group 2, excretion of U-HPr increased after OVX and had reached a level of approximately twice the baseline values by 10 months; then it gradually came down to the original level. In Group 3, however, U-HPr excretion remained at the same level as the baseline value, as it did in Group 1. In Group 4, it was remarkably reduced down to 50-60% of the baseline values. Serum BGP level was markedly reduced in Group 4. Serum 24,25(OH)2D levels were markedly increased in Groups 3 and 4.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study of the actions of tamoxifen, estrogen and progesterone in the ovariectomized rat

This study was undertaken to examine the separate and combined effects of tamoxifen (T), estrogen (E2) and progesterone (P) treatment on ovariectomized (Ooph) rats. The animals were treated for 40 days. Ovariectomy reduced cancellous bone volume at the proximal tibia by 50%. Estradiol treatment completely prevented the bone loss and further increased bone volume 77% over the level for the control group. Tamoxifen also prevented the ovariectomy induced bone loss, but significantly reduced the increase in cancellous bone induced by estradiol. In the ovariectomized rats, cancellous bone apposition rate increased 23%. This increase was suppressed 63% by estradiol, and only 18% by tamoxifen. Tamoxifen significantly suppressed the inhibitory effect of estradiol on cancellous bone apposition rate. In contrast, the effect of progesterone treatment was only marginal. Our findings indicate that the action of tamoxifen on bone is influenced by the ambient level of circulating estradiol, such that in estrogen deficiency, tamoxifen has a weak estrogen agonist action on bone, and in the presence of estrogen it has anti-estrogen actions, with the dose level and mode of administration employed. These conclusions have implications for the use of tamoxifen in the treatment of pre- and postmenopausal women.

hPTH 1-34 treatment of osteoporosis with added hormone replacement therapy: biochemical, kinetic and histological responses

Twelve patients with vertebral fracture osteoporosis were recruited into a trial of treatment with hPTH 1-34 by daily injection for 1 year combined (from the 5th month) with an anti-resorptive agent (oestrogen, n = 9; nandrolone, n = 3). Treatment outcomes were monitored by biochemical and radiotracer measurements together with histomorphometry of transiliac biopsies before and at the end of treatment following double in vivo pre-labelling with demethylchlortetracycline. Indices of whole body bone formation, obtained from the analysis of 85Sr data, showed substantial increases (P less than 0.005) for all three indices measured) while biochemical (hydroxyproline) and kinetic measurements of bone resorption showed modest and equivocal changes only. As a result calcium balance improved. Gastrointestinal calcium absorption showed a tendency to improve, while urine calcium decreased; but these changes were statistically not significant except for radiocalcium absorption in the oestrogen treated subgroup. Histomorphometry revealed substantial increases in cancellous bone volume as reported previously with hPTH 1-34 given alone. However, iliac (as distinct from whole body) indices related to bone formation and resorption appeared to have returned towards pre-treatment values by the time of the second biopsy under the influence of the anti-resorptive agent given with the hPTH 1-34. It is confirmed that hPTH 1-34 therapy can increase iliac cancellous bone mass (as well as spinal cancellous bone mass as reported earlier) without a long-term increment in whole body bone resorption, providing the hPTH is combined with an anti-resorptive agent.

Contribution to the study of tetracycline bone side-effects. Absence of calcium deposition impairment in the trabecular bone of a patient treated during 3.5 years with doxycycline

Tetracyclines are easily incorporated into bone; whether bone formation is impaired during this process is still a matter of debate. We therefore studied, by histomorphometry, fluorescence microscopy, and microradiography, a sample of trabecular bone from a patient with a total hip arthroplasty, treated without interruption for 3.5 years with doxycycline because of a pertrochanteric abscess. Absence of osteomalacia and a low-mineralization score of the edges of the trabeculae similar to that observed in a control group of 12 subjects suggest no interference by doxycycline with calcium deposition in bone.

Iliac bone biopsies at the time of periarticular stress fractures during fluoride therapy: comparison with pretreatment biopsies

We attempted to establish whether systemic changes in trabecular bone explain the development of stress fractures in the lower limbs during fluoride therapy for osteoporosis. To this end we compared transiliac bone biopsies obtained before treatment with those taken around the time of stress fractures after 14.3 +/- 10.9 (SD) months of therapy in six patients (group A). Biopsies from a comparable group of six patients without stress fractures at the time of the second biopsy (after 11.9 +/- 2.7 months of treatment) served for comparison (group B). The biopsies were processed undecalcified and examined by routine histomorphometry. The second biopsies did not show any significant improvement in mean bone volume or trabecular architecture. Although the second biopsies in group A had increased erosion surfaces (p less than 0.05) and greater osteoid volume (p less than 0.05), group B biopsies showed no difference in erosion surfaces but an increase in all osteoid parameters: osteoid volume (p less than 0.05), osteoid surface (p less than 0.05), and osteoid seam thickness (p less than 0.01). We reached the following conclusions: (1) the combination of increased erosion and replacement of removed bone by as yet unmineralized osteoid in the stress fracture group must have weakened bone and allowed the development of stress fractures. (2) Stress fracture patients may have mounted a less vigorous osteoblast response to fluoride than non-stress fracture patients. Under these conditions microfractures are likely to heal poorly and propagate to develop into full stress fractures. (3) Renal failure is a contraindication to fluoride therapy.

Effect of calcitonin administration on young pig trabecular bone remodeling

Ten-week-old pigs were treated with 4 different treatment schedules of porcine calcitonin for 2 months. Groups C1 and C4 received continuous treatment: C1 had daily IM injections (4 IU/kg/BW (body weight) each injection), and C4 was infused with a minipump implanted subcutaneously delivering 4 IU/kg/BW/day. Groups C2 and C3 received intermittent calcitonin treatment (each injection 4 IU/kg/BW): C2 was given 1 out of every four days, C3 was injected 5 consecutive days out of 20 days. The total dosage received in C1 versus C4 and C2 versus C3 were the same. Results were evaluated by histomorphometry after double tetracycline labeling on iliac trabecular bone. Resorption surfaces were decreased in groups C2, C3 and C4, but bone volume, osteoclast surfaces, and interstitial bone thickness were not modified in any group receiving calcitonin. Osteoblast and mineralizing surfaces were increased in group C2, C3 and C4. Plasma 1,25-dihydroxyvitamin D concentration and bone formation rate were increased in groups C2 and C4. Plasma immunoreactive parathyroid hormone levels and parathyroid weights were not increased in any treated groups. In conclusion, 2-month calcitonin treatment did not decrease the amount of bone resorbed in growing pigs. Continuous calcitonin infusion and intermittent calcitonin administration induced an increase in the extent of active bone formation which might be in part dependent on an increased production of 1,25 dihydroxyvitamin D.

Control of primary osteosarcoma with chemotherapy

High-dose methotrexate with citrovorum factor "rescue" (MTX-CF) produced an apparent complete response of the primary tumor in three patients with osteosarcoma. The response was sustained with MTX-CF, intra-arterial cis-diamminedichloroplatinum II (CDP) and Adriamycin (doxorubicin) for 18 months. Treatment was then electively discontinued. Local recurrence occurred in two patients, 6 and 4 months later, respectively. MTX-CF was reinstated and a complete response was again achieved in one patient. This has been maintained for 15+ months with MTX-CF and intra-arterial CDP administered for 13 of the 15+ months. Reinduction with MTX-CF failed in the second relapsed patient but an apparent remission was again achieved with radiation and intra-arterial CDP. This has been maintained with intravenous CDP, cyclophosphamide and phenylalanine mustard for 14+ months. A complete response in the primary tumor was still present in the nonrelapsed patient, 42 months from diagnosis. All patients have remained free of pulmonary metastases, 40+ to 42+ months from diagnosis.

Synthesis and biological activities of neurokinin alpha and beta

Two novel neuropeptides, neurokinin alpha and beta isolated from porcine spinal cord, were announced. We have synthesized neurokinin alpha as Asp-Met-His-Asp-Phe-Phe-Val-Gly-Leu-Met-NH2, which were 98-99% pure by HPLC. Assays on the isolated guinea pig ilium showed neurokinin alpha to have 81% and neurokinin beta to have 65% of the activity of Substance P. Knowledge of these three related peptides having a common activity opens new considerations of their intrinsic physiological roles in neurotransmission versus pharmacological activities, and reappraisal of the diverse activities of Substance P including that in the inflammatory response of the eye.