Colorimetric evaluation of cultured osteoblast-like cells (ROS 17/2.8)

We have developed a colorimetric method for evaluating the number of osteoblastic cells in culture without destroying the cells. This assay is based on the staining of basophilic cellular compounds with methylene blue. The dye bound by the cells is released at low pH and measured in a spectrophotometer at 662 nm. Linear correlations exist between the absorbance measured by the methylene blue assay and the number of cells seeded, the total cellular protein content, and thymidine labeling. This colorimetric method has the advantage of preserving cell integrity. After destaining, scanning electron microscopy can be performed on well preserved cell morphology.

Adverse effects of strenuous exercise: a densitometric and histomorphometric study in the rat

To investigate the manner in which cancellous bone in different skeletal sites and within a bone site adapts to strenuous training, 5-wk-old male rats were subjected to intensive treadmill running [80% of maximal O2 consumption (VO2max)] for 11 wk. VO2max, tibia length, and bone mineral density were measured. Histomorphometric analysis was performed in the epiphysis, primary spongiosa (1 zero sp) and secondary spongiosa (2 zero sp) of the contralateral proximal tibia, and the 2 zero sp of thoracic and lumbar vertebrae. VO2max was increased by 39%. No changes were observed in vertebrae. Tibia length, 1 zero sp bone volume, and number of trabeculae were significantly decreased, indicating a retarded longitudinal bone growth. Bone mineral density in the proximal tibia was significantly decreased. In the epiphysis, a trabecular thinning and an increase of trabecular number were shown. In the 2 zero sp, bone volume and number of trabeculae were significantly decreased. The increased total eroded surfaces could indicate an early but transient increase in bone resorption activity. Osteoid thickness was reduced, whereas osteoclast number and osteoid surfaces were unchanged, suggesting that the observed bone loss was mostly due to an impaired osteoblastic activity. In conclusion, 1) strenuous training in young rats reduces longitudinal bone growth and induces bone loss, 2) the cancellous bone adaptation is site specific, and 3) the bone loss is mainly due to decreased osteoblastic activity rather than a global adaptation of bone remodeling.

Histomorphometric analyses of cancellous bone from COSMOS 2044 rats

The influence of 14 days of spaceflight on cancellous bone of male Wistar rats was assessed by histomorphometric analysis. In proximal tibia, no difference was found between flight, synchronous, vivarium, and basal groups for epiphyseal bone volume or trabecular arrangement. In metaphysis, primary spongiosa width was reduced in flight rats, suggesting an alteration in bone longitudinal growth. In flight rats, secondary spongiosa evidenced a trend toward decreased bone mass, trabecular number and thickness, and osteoid surfaces, whereas there was a tendency toward increased osteoclast number compared with vivarium control but not with synchronous rats. In femoral fossa trochanteri, an area facing deep muscular insertions, no changes in bone volume or structure were noted among the different groups. However, a reduction of osteoid surfaces was seen in flight and synchronous groups compared with the other groups. Resorption activity was increased in flight rats compared with control rats. In thoracic vertebral body, osteoblastic surfaces decreased similarly in flight and synchronous rats. In lumbar vertebral body, decreased osteoblastic surfaces and increased osteoclastic parameters were observed in flight and synchronous rats. The more striking effects of spaceflight were the decrease in tibial primary spongiosa width and the increase in resorption activity of the femoral fossa trochanteri. In all other sites, cellular alterations appeared similar in flight and synchronous rats, suggesting a role for physiological stress. The time course of events would depend on initial growth and turnover rates of bone, its weight-bearing function on earth, and the presence of muscular insertions.

[Tobacco as risk factor of osteoporosis, myth or reality?]

To evaluate smoking as a risk factor for osteoporosis, we performed a qualitative analysis of 40 international studies investigating statistical associations between smoking and osteoporosis related endpoints. Using standardized causality assessment criteria, we failed to demonstrate a relationship between smoking and osteoporosis. Because such a relationship is biologically plausible, we then undertook a quantitative metaanalysis of 8 epidemiological hip fracture studies. Relative risk, estimated as the "combined odds ratio", was 1.33 (95% confidence interval 1.14-1.54) in the case-control studies and 1.63 (95% confidence interval 1.27-2.09) in the prospective studies. These data suggest that smoking is a modest risk factor for osteoporosis. However, studies of effects of smoking on peak bone mass would be of interest in view of the prevalence shift of smoking towards increasingly young age groups. Early exposure to smoke may decrease peak bone mass. Furthermore, Kiel recently found evidence that replacement hormone therapy may be ineffective in preventing hip fractures in postmenopausal women who smoke. Reducing smoking is an important goal for the primary and secondary prevention of osteoporosis in teenagers and postmenopausal women, respectively.

[Thrombotic thrombocytopenic purpura and ankylosing spondylarthritis. Apropos of a case]

The authors report a case of thrombotic thrombocytopenic purpura (TTP) which revealed a hitherto unrecognized ankylosing spondylitis. After a 4-year follow-up, the spondylitis is still progressing in its axial and/or peripheral form, and TTP has not relapsed. TTP is usually primary, but numerous forms consecutive to various diseases, and notably autoimmune diseases, have been reported. The TTP-ankylosing spondylitis association is extremely rare: analysis of the literature yielded only one case. The authors discuss the hypothesis of a common triggering factor.

Possible nonlinear effects of exercise on bone in male subjects over age 60 years

We investigated the relationships among bone mass, bone cell activities, and exercise level in 20 healthy 61-77 year old male volunteers divided into three groups according to the time they physically trained per week: nine subjects training less than 3 hr/week, five subjects between 3 and 6 hr/week and six subjects more than 6 hr/week. Physical performance was evaluated by VO2 max (ml min-1 kg-1). After tetracycline double labeling, iliac crest biopsy was obtained from each subject. The longer the physical activity, the higher the VO2 max. Subjects exercising between 3 and 6 hr/week revealed higher adjusted appositional and bone formation rates than all the others; mass and structural parameters also showed higher (nonsignificant) values. For the whole population VO2 max appeared negatively related to cortical thickness, cancellous bone volume, and trabecular thickness. These alterations were accompanied by increased cancellous bone turnover; this was evidenced by an increase in activation frequency and in resorption and formation rates as VO2 max increased. The bone remodeling periods tended to decrease also. Whatever the bone turnover rate, subjects were in steady state as far as their bone balance was concerned. Relationships between VO2 max and mineral apposition rate on the one hand and VO2 max and resorption surface on the other hand were best fitted by a quadratic model, suggesting a possible nonlinear effect of physical training on bone mass. We hypothesize that there is a threshold (6 hr/week) determining different effects. Adjustment of bone mass and trabecular arrangement were completed at time of biopsy and reflected probably past and transient bone imbalance.(ABSTRACT TRUNCATED AT 250 WORDS)

Microgravity and bone adaptation at the tissue level

Our knowledge of the adaptation of human bone microgravity remains poor despite long-term Russian spaceflights and the recent use of accurate techniques for bone mass measurements. The extent of bone deficits in the adaptation of the whole skeleton is not clear. At the tissue level, bone resorption and formation activities have been studied only in bones from rats after spaceflights lasting a few days to 3 weeks. In these animals, architectural features consistent with osteoporosis have been found in the proximal tibia. In pregnant animals the osteoclast population is increased at other skeletal sites. In areas of weight-bearing bones that are not protected by muscular insertions, bone resorption is not markedly altered after 7 days of spaceflight and bone formation is reduced. In areas of weight-bearing bones with muscular insertions and in non-weight-bearing bones, similar changes in bone cell activity are delayed. The severity of the response seems to vary with the location of the bone in the skeleton and its initial level of bone turnover. After 12.5 days the acute bone changes are less and no additional changes are observed after 21 days in space. We conclude that generalized bone deficits do not appear to be a consequence of microgravity but occur in localized areas according to the level of modeling and remodeling and of the support function of each bone at 1 g.

Bone tissue response to four-month antiorthostatic bedrest: a bone histomorphometric study

A histomorphometric analysis were made on iliac crest biopsies from eight healthy male volunteers submitted to a 4-month antiorthostatic bedrest. Bone mass and bone cell parameters, reflecting resorption and formation activities, were measured before and after the bedrest period. Trabecular bone volume and mean cortical thickness were not modified despite a decreased number of trabeculae and nonsignificant increase of the trabecular thickness; total and active resorption surfaces and the number of osteoclast per mm2 of trabecular surfaces do not vary significantly. Osteoid thickness does not vary but we found a reduced osteoid surface and a nonsignificant decreased osteoid volume. Our results suggest that bone architecture may be more affected by the reduction of mechanical forces than the bone mass. These modifications were supposed to be the result of an accelerated bone turnover in the early stage of immobilization. In this study, we failed to find disuse osteoporosis; however, we must point out that the new organization of the trabeculae could affect the bone mechanical properties.

Bacterial pyomyositis in a patient with a multiple myeloma

Pyomyositis is relatively rare in regions with a temperate climate. The most common aetiologic agent is staphylococcus aureus. Most patients with pyomyositis from temperate regions involve immunocompromised states. Because of the rarity, it is often initially misdiagnosed. Computed tomography scan is considered the most helpful tool for the diagnosis of pyomyositis. We present a case in a patient with multiple myeloma.

Néphrite interstitielle aiguë avec uvéite. A propos d'un cas

Dobrin et al described in 1975 the first case report with acute renal failure due to tubulo-interstitial nephritis accompanied by uveitis and an inflammatory syndrome. The young adults are frequently involved and the complete resolution is usually obtained after corticosteroid treatment; this contrasts with the tendency towards relapse of the uveitis. The etiology and the pathogenesis of this syndrome remain unknown. We report the case of a woman which the renal function was incompletely reversible with corticosteroids.

Human and Drosophila homeodomain proteins that enhance the DNA-binding activity of serum response factor

Cells with distinct developmental histories can respond differentially to identical signals, suggesting that signals are interpreted in a fashion that reflects a cell's identity. How this might occur is suggested by the observation that proteins of the homeodomain family, including a newly identified human protein, enhance the DNA-binding activity of serum response factor, a protein required for the induction of genes by growth and differentiation factors. Interaction with proteins of the serum response factor family may allow homeodomain proteins to specify the transcriptional response to inductive signals. Moreover, because the ability to enhance the binding of serum response factor to DNA residues within the homeodomain but is independent of homeodomain DNA-binding activity, this additional activity of the homeodomain may account for some of specificity of action of homeodomain proteins in development.

Effect of a five-week swimming program on rat bone: a histomorphometric study

To specify the exercise-induced changes on different skeletal sites, the effect of a 5-week endurance swim training was studied in rats. Eighteen Lyon strain (Sprague-Dawley) 5-week old female rats were divided into nine sedentary and nine swimming rats. Each swim training session was increased by 15 minutes from 2-6 hours per day. A histomorphometric study was performed at the primary and secondary spongiosa of the distal femur and at the secondary spongiosa of lumbar and thoracic vertebral bodies. After training, bone loss was observed in the secondary spongiosa of lumbar vertebral bodies (24.7%) and in the primary spongiosa of distal femur (15.2%). A tendency to bone loss was also detected in the secondary spongiosa of distal femur (10.8%), whereas no change was detected in thoracic vertebral bodies. In secondary spongiosa, bone loss was accompanied with a thinning of trabeculae. Total eroded surfaces and osteoid surfaces were significantly decreased in the three studied skeletal sites, suggesting a decreased bone turnover. The decreased thickness of osteoid seams in both lumbar vertebrae and distal femur could mean that the osteoblastic activity has also been altered at the cell level, leading to thinning of trabeculae. Five-week swim training with such duration and intensity of exercise appears unable to increase bone volume in rats and, therefore, causes adverse effects. The three studied bones seemed to adapt differently to experimental conditions. The lack of ground reaction forces induced by water immersion might have contributed to the observed bone loss. "Normal" gravity would be an important cofactor in the osteogenic effects of exercise.

Contributions of chronological age, age at menarche and menopause and of anthropometric parameters to axial and peripheral bone densities

Bone mineral density (BMD) was measured in 128 normal postmenopausal women at different skeletal sites: lumbar spine and proximal femur, using dual-energy X-ray absorptiometry (DXA), and the cancellous and cortical envelopes of the distal third of radius and tibia, using precise low-dose quantitative computed tomography (QCT). Multivariate analysis included chronological age, ages related to menstrual history (menopause and menarche) and anthropometric factors, e.g. height and weight, as independent predictive variables. Weight is a much-studied predictor of bone density. At sites of high bone turnover, i.e. cancellous envelope, the effect of weight appeared overshadowed by estrogen-related parameters: age-past-menopause was the first predictor of BMD in the cancellous compartment of radius and in Ward's triangle, and the number of reproductive years was the strongest predictor of BMD in the cancellous compartment of tibia and in the spine (L2-4). This suggests that in addition to menopause, the length of menstrual life should be considered as an explanation for the variations in current bone mass in postmenopausal women. At the cortical level of radius, the effect of chronological age was predominant. At the cortical level of tibia, height and weight were the best predictors of BMD. We conclude that the influence of parameters related to menstrual history is predominant in sites with mainly cancellous tissue and that anthropometric factors constitute the best predictors of BMD in the cortical sites of weight-bearing bones.

Bone mass and bone cellular variations after five months of physical training in rhesus monkeys: histomorphometric study

Five Rhesus Monkeys (Macaca mulatta), a suitable nonhuman model, performed 5 months of rope-climbing exercise. Duration of the training sessions was progressively increased to reach 1 hour/day after 1 month of training and was maintained until the end of the experiment. Bone mass parameters, bone resorption, and bone formation activity were measured by histomorphometric analysis on iliac crest bone biopsies before and after the experiment. Mineral apposition rate was measured in cortices and trabecular bone after double calcein labeling. Five months of rope-climbing exercise had determined a significant decrease of bone volume with a slight decrease of the number and thickness of trabeculae. This might induce an alteration of biomechanical properties of bone. These architectural modifications were associated with a nonsignificant decrease of bone resorption activity. But the main effect of training was an important decrease of bone formation activity without change of the mineral apposition rate. Endurance exercise at low intensity has determined a decreased bone turnover with osteoblastic depression. This animal experiment points out that exercise modalities might be important in the bone response to training and should be carefully defined for preventive use in humans.

[In vitro identification of a mononuclear precursor of osteoclast]

Osteoclast is derived from mononuclear hematopoietic stem cells, most likely within the granulocyte-macrophage lineage. The exact differentiation process of osteoclasts precurssors has only been partially uncovered. The authors isolated in vitro, from the medullary bone of hens a mononuclear precursor of the osteoclast. This cell expressed several characteristics of mature and multinucleated osteoclast including the capacity to resorb the extracellular bone matrix.

[Bone histomorphometric study in involuted fractured osteoporosis treated with 1-ethane-1-hydroxybiphosphonate (etidronate) during one year]

The efficacy of the biphosphonate etidronate has recently been demonstrated versus the vertebral fracture rate in fractured involuted osteoporosis in the literature. However, it would appear that the increase in bone mass (measured from the calcium density) may alone account for these results. The authors undertook a histomorphometrie study in 20 patients with a group mean age of 55 years presenting recent vertebral fracture in the context of osteoporosis, in order to assess the cell changes which may affect bone quality. This factor remains the only one which can account for the reduced number of fractures. The patients received treatment with phosphorus (1,500 mg/d) for 3 days followed by etidronate (400 mg/d) for 14 days every 90 days. A permanent daily intake of 50 mg of calcium and 400 IU of vitamin D was also administered. Each patient underwent bone biopsy of the iliac wing before and after one year of treatment (4 cycles). No change in the bone mass or architectural parameters was observed. However, general slowing of the bone remodeling was found, affecting the natality and activity of the osteoforming and osteoresorbing cells. However, this remodeling which is traditionally uncoupled in osteoporosis was once more coupled. This results in a slowing of bone loss, ageing of the bone present and no change in the architecture. Thus, the diphosphonates appear to have a beneficial effect on the quality of bone rather than on its quantity. This represents a novel approach to the treatment of osteoporosis.

Retrovirus-mediated gene transfer of a human c-fos cDNA into mouse bone marrow stromal cells

A cDNA encoding a complete human c-fos protein was isolated and inserted into two different murine MoMuLV-derived recombinant retroviruses allowing expression of c-fos protein in different cell types. One c-fos-expressing retrovirus, chosen for its ability to express high levels of proteins in fibroblast-like cells, was shown to potentiate long-term cultures of mouse bone marrow stromal cells in vitro and therefore constitutes a potential tool for immortalizing such cells. Moreover, when tested in an in vitro differentiation assay, stromal cells constitutively expressing c-fos favor the granulocyte differentiation of hematopoietic precursors. Interestingly, retroviruses expressing v-src and v-abl oncogenes, included as controls in our experiments, do not produce any detectable effects, whereas those expressing polyoma virus middle T antigen facilitate long-term growth in vitro of stromal cells that favor the macrophage differentiation pathway of bone marrow stem cells. Our observation supports the idea that constitutive expression of some oncogenes, including c-fos and polyoma virus middle T antigen, may influence cytokine production by bone marrow stromal cells.