Biomedical subjects

S Palle

Publications and source records attributed to S Palle.

At least 19 recordsLinked to original sources

PubMed1998

Hindlimb unloading in rat decreases preosteoblast proliferation assessed in vivo with BrdU incorporation.

Immobilization affects bone formation. However, the mechanisms regulating the decrease in osteoblast recruitment remain unclear. The aim of our study was to determine in vivo osteoblastic proliferation after short-term immobilization among the different bone compartments. Twelve Wistar 5-wk-old rats were assigned to two groups: six tail-suspended animals for 6 days and their six age-related controls. Osmotic minipumps, each containing 40 mg of bromodeoxyuridine (BrdU), were implanted intraperitoneally at day 4 until euthanasia. Histomorphometric measurements found a significantly lower bone volume in primary (ISP, -22%) and secondary spongiosa (IISP, -37%) in unloaded rats compared with their age-related controls. BrdU immunohistochemistry showed that the proliferation capacity of osteogenic precursors in ISP (-29%) and preosteoblasts in IISP (-80%) and in periosteum as well as bone marrow cells (-40%) was lowered by unloading. We demonstrated in vivo for the first time that 6-day tail suspension induced a significant decrease in proliferation of periosteal and trabecular preosteoblasts in ISP and IISP as well as in bone marrow cells.

Animals↗

PubMed1997

Demonstration of feasibility of automated osteoblastic line culture in space flight.

There is a large body of evidence that microgravity- or immobilization-induced bone loss is mainly related to osteoblastic cell impairment. Osteoblasts are sensitive to increased mechanical stress and could therefore be responsible for unloading-induced bone changes. However, the nature of osteoblast involvement remains unclear. The effects of the space environment on cells have been studied extensively, but little information about anchorage-dependent cell cultures of the 25 different cell types flown in space has been published. We studied the effects of long-term weightlessness on the cell shape of cultured osteoblasts during the Russian Bion 10 space-flight. This experiment required the development of special automatic culture devices (the plunger-box culture system) finalized with the constructors. Multiple feasibility experiments were performed to allow osteoblast culture for 6 days in microgravity. The study revealed plunger-box biocompatibility; optimization of ROS 17/2.8 (mammalian adherent cells) culture under closed conditions (without gas exchange); and transport of viable cells for 5 days. During the 6 days of microgravity, the growth curves of ground controls and cells in space were roughly similar. Alkaline phosphatase activity was enhanced twofold in microgravity. ROS 17/2.8 cell morphology began to change significantly after 4 days of microgravity; they became rounder and covered with microvilli. At the end of the flight, the cells exhibited mixed morphological types, piling cells, stellar shape, and spread out cells, resembling ground controls or 1g flight controls (centrifuge). We demonstrated that ROS 17/2.8 cells were viable during a 6 day automatic culture in space and were sensitive to space related conditions. They adapted their structure and function to this environment, characterized by loss of mechanical stimuli.

Alkaline Phosphatase↗

PubMed1997

Pre-osteoblastic proliferation assessed with BrdU in undecalcified, Epon-embedded adult rat trabecular bone.

We evaluated bromodeoxyuridine (BrdU) immunohistochemistry in undecalcified adult rat tibiae to study cell kinetics in various bone compartments: primary and secondary spongiosae, periosteum, and bone marrow. Several regimens of BrdU administration were tested (i.p. injections and osmotic minipumps). We compared LR White resin, methylmethacrylate, and Epon-araldite embedding, microwave irradiation for antigen retrieval, several concentrations of sodium ethoxide for deplastification, and various DNA denaturation procedures. Paraffin-embedded decalcified tibiae and Epon-embedded bowel were used as positive controls. The best results were obtained in rats labeled with 40 mg of BrdU for 72 hr using osmotic minipumps. The procedure using a Microprobe system in Eponembedded bone tissue with a sodium ethoxide concentration of 50% for two intervals of 20 min provided the best staining quality and tissue preservation. Labeled pre-osteoblastic cells and bone marrow cells could be counted. Epon embedding allowed preservation of tetracycline double labeling performed 1 to 5 days before sacrifice. The number of labeled pre-osteoblastic cells was correlated with the double-labeled surface area measured histomorphometrically.

Animals↗

PubMed1995

Physical exercise during remobilization restores a normal bone trabecular network after tail suspension-induced osteopenia in young rats.

To determine how bone recovers from immobilization-induced bone loss and to specify whether its recovering capacity is improved by physical exercise, 5-week-old male Wistar rats (287.07 g +/- 10.65 SD) were tail suspended for 14 days, then returned to either normal weight-bearing (R) or controlled physical exercise for 28 days (R + E). Bone mineral density (BMD) was measured in three parts of the femur. Using histomorphometric analysis, bone mass and architecture were estimated in the primary (1 degree sp) and secondary spongiosa (2 degrees sp) of the proximal tibial metaphysis. Bone cellular parameters were measured in the 2 degrees sp of the tibia. Tail suspension induced a significant decrease in BMD, 2 degrees sp bone mass, mineral apposition rate, and bone formation rate and marked alterations of the trabecular network. In R rats, BMD was still significantly decreased, except in the distal part of the femur. Long-bone lengthening was significantly altered. The 2 degrees sp bone mass returned to the age-matched control values; however, the trabeculae were still significantly thinner and bone resorption was significantly higher. R + E rats had a normal long bone lengthening and a significant increase in 2 degrees sp bone mass and trabecular thickness when compared with R rats. Bone resorption was significantly depressed, and osteoid surfaces and thickness were significantly increased. Thus, although bone mass returns to normal values in the R group, trabecular alterations persist.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗

PubMed1995

Effect of physical training on bone adaptation in three zones of the rat tibia.

This study as been conducted to examine the effects of physical exercise on the bone trabecular network and the cellular adaptations in three different areas of a single bone, the tibia. Male Wistar rats (9 weeks old) were treadmill-trained for 0, 3, 4, or 5 weeks at 60% of their measured maximal O2 consumption (VO2max). Histomorphometric analysis of the proximal tibia of running and age-matched control groups was performed in the epiphyseal trabecular bone, in the primary spongiosa and in the secondary spongiosa. Dynamic and static bone cell activities and serum calcium and phosphorus levels were measured. VO2max increased significantly by 18.4% after 5 weeks of training. In the epiphysis, a 9% increase in bone volume, associated with more numerous trabeculae (8%) was detected the third week of training. In primary spongiosa a significant increase (6.7%) in newly formed trabeculae was found. In secondary spongiosa bone volume increased significantly by 26.2% the fifth week of exercise and was associated with thicker trabeculae. The number of osteoclast profiles was significantly depressed. Osteoid surfaces and bone formation rate increased significantly in weeks 3 to 5. Serum calcium levels were found to be significantly decreased in weeks 3 and 4. There was no change in osteoid thickness or mineral apposition rate. These results suggest 1) a rapid increase in osteoblastic recruitment without change of the cell activity in response to moderate exercise; 2) a decreased bone resorption associated with a marked increased in bone formation from the third week of training; 3) adaptation of the trabecular network to exercise that seems to be bone-site-dependent, suggesting a cell sensitivity to training-engendered strain distribution within the bone or to strain-related local factors.

Adaptation, Physiological↗

PubMed1994

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.

Animals↗

PubMed1994

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.

Animals↗

PubMed1993

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)

Aged↗

PubMed1993

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.

Animals↗

PubMed1992

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.

Adult↗

PubMed1989

Evaluation of the osteoclastic population in iliac crest biopsies from 36 normal subjects: a histoenzymologic and histomorphometric study.

After histochemical staining of tartrate-resistant acid phosphatase (TRAP) activity, the total and active trabecular resorption surfaces and the number of osteoclasts were determined by histomorphometry on iliac crest biopsies from 36 healthy volunteers. The subjects were separated into three groups according to age and sex. Total trabecular resorption surface showed no significant variation in any group, but the fraction of active resorption surface was significantly higher in the older population. The number of TRAP cells per mm2 of section area, related to trabecular bone volume or surface, showed a significant increase in elderly subjects. The mean osteoclast interface was similar in all the groups. We found a significant decrease in resorption depth between young and old populations. These results are consistent with a reduced activity of bone-resorbing cells in advancing age. These normal values, established after histochemical identification of osteoclasts, may be applied for evaluating abnormal bone-resorbing cell activity in metabolic bone diseases.

Adult↗

PubMed1989

Effects of a bisphosphonate (1-hydroxy ethylidene-1,1 bisphosphonic acid) on osteoclast number during prolonged bed rest in healthy humans.

Acute osteoporosis is known to occur after immobilization in spinal cord injured patients and is related to an early increase in osteoclastic bone resorption. Whether osteoporosis develops in healthy immobilized human patients is still a matter of controversy. Furthermore, acute osteoporosis was thought to be a good model to study the effects of weightlessness on the human skeleton and to adapt preventive procedures. A bed rest experiment was developed in the USSR on 15 healthy human volunteers to determine the precise effects on bone structure and cell activities. A preventive protocol, including an anti-osteoclastic drug (1-hydroxyethylidene-1,1 bisphosphonic acid; K salt) was investigated. Two transiliac bone biopsies were performed on the 15 individuals before and at the end of the 120-day bed rest period. Undecalcified bone biopsies were studied with automatic and semi-automatic image analyzers specially devoted to bone histomorphometry. Trabecular bone volume, osteoid amount, and eroded surfaces were measured. Osteoclast number was measured after histochemical identification of tartrate-resistant acid phosphatase. After the bed rest period, an insignificant bone loss was observed in healthy humans while osteoclast number was highly increased. In bisphosphonate-treated subjects, osteoclast number was markedly reduced and so was osteoid amount. Bisphosphonates were shown to present a highly cytotoxic activity on osteoclasts, a finding that has never been demonstrated in normal subjects.

Adult↗

PubMed1989

Bone changes in alcoholic cirrhosis of the liver. A histomorphometric study.

The effects of alcoholic liver cirrhosis on the calcium, calciotropic hormones (parathyroid hormone and 25 hydroxy vitamin D) and testosterone were examined in twenty men. A transiliac bone biopsy was performed in each patient. A double tetracycline labeling was done in 17 patients. Radiological signs of osteoporosis (crushed vertebrae and rib fractures) were rarely observed but a low trabecular bone volume (BV/TV) was consistently encountered (BV/TV = 14.2 +/- 4.6; normal 18.8 +/- 4.8; p less than .001). Osteomalacic signs were never observed in spite of very low calcium and 25 hydroxy vitamin D levels in the blood. Increased osteoclastic eroded surfaces (ES/BS = 8.1 +/- 5.2; normal 3.7 +/- 1.1; p less than .001) were not related with an hyperparathyroidism but a significant correlation was found with testosterone levels (r = .45; p less than .05). Histodynamic measurements indicate a drastically decreased osteoblastic activity with a very low bone formation rate (BFR/BS = .009 +/- .001; normal .0175 +/- .0125; p less than .001). This could explain the net increase of eroded surfaces and that osteomalacia cannot be observed even in the presence of profound calcium and vitamin D changes in alcoholics.

Aged↗

PubMed1988

Hypocalcemia response following calcitonin administration: lack of correlation with osteoclast number determined after histoenzymologic identification in osteoporosis.

The relationship between calcitonin-induced hypocalcemia and histomorphometric parameters of bone resorption was examined in iliac crest biopsies of 30 osteoporotic patients aged 55-86 years all of whom had received a single injection of 100 UI of salmon calcitonin. Number of osteoclasts and active resorption surfaces were determined after histoenzymologic staining based on osteoclastic tartrate resistant acid phosphatase content. No significant correlation could be demonstrated between the drop of hypocalcemia and the different histomorphometric parameters. It can be concluded that the calcitonin test is useless in osteoporosis.

Aged↗

PubMed1988

Effects of a one-year administration of phosphate and intermittent calcitonin on bone-forming and bone-resorbing cells in involutional osteoporosis: a histomorphometric study.

The bone histomorphometric effects of intermittent phosphate and calcitonin therapy during 1 year were analyzed in 15 involutional osteoporotic patients. Phosphate was administered continuously (1.5 g/day) and calcitonin was injected during 5 days every third week (50 IU/day). The bone cell response was analyzed in two separate groups, according to the amount of trabecular bone present in the iliac bone biopsy: patients with trabecular bone volume (TBV) beyond the histomorphometric spontaneous fracture threshold (0.16 mm3/mm3) (group 1; 11 patients) and patients with TBV above this threshold (group 2; 4 patients). In group 1, the treatment significantly increased TBV from 0.113 +/- 0.025 to 0.156 +/- 0.046 mm3/mm3 by thickening the existing trabeculae rather than by creating new trabeculae; stimulation of bone formation rate (+ 50%) and significant reduction in active trabecular resorption surfaces (from 0.021 +/- 0.013 to 0.010 +/- 0.006 mm2/mm2; P less than .05) may have led to positive bone balance. In group 2, TBV was not changed because of the treatment's relative inefficiency for reducing the bone-resorbing cell activity, leading to likely persistent negative bone balance. Cortical thickness did not change in either group. This study confirms the positive effectiveness of continuous treatment with phosphate and intermittent calcitonin during 1 year on bone balance in involutional osteoporosis with low amount of bone. The lack of response in patients with normal amount of bone must be verified before raising the hypothesis of different bone cell activity and before anticipating the therapeutic response according to local bone mass besides bone remodeling status in osteoporosis.

Aged↗

PubMed1988

Improved algorithms for automatic bone histomorphometry on a numerized image analysis system.

Quantitative histological methods have proved to be the most effective methods in bone disease research. Faster and more accurate techniques are currently needed. We have developed a simple digitized image analysis system which allows accurate measurements of trabecular bone mass. The algorithm is based on the 'four-connected sets' mathematical theory. Given a numerized image displayed by a CCD camera, the algorithm recognizes all possible four-connected sets and provides area measurements. The first procedure automatically eliminates small, irrelevant profiles (wrinkles, cell nuclei, etc.) while larger profiles are erased interactively. The second procedure similarly erases the artefactual defects within the trabeculae (artefactual cracks or empty osteocytic lacunae). The method was shown to be very accurate and time-saving.

Algorithms↗

PubMed1988

Trabecular bone remodeling after seven days of weightlessness exposure (BIOCOSMOS 1667).

Seven male rats were exposed to 7 days of weightlessness in the Soviet mission COSMOS 1667 and compared with seven control rats by bone histomorphometric methods. In proximal tibial metaphysis, the trabecular bone volume was markedly reduced in flight animals. Trabeculae were decreased in number and thickness; this probably leads to alteration of bone mechanical properties. Formation activity (reflected by measurements of osteoid seams) was decreased at trabecular and endosteal levels. Resorption activity (estimated by count of osteoclast number and active resorption surfaces using a histoenzymologic method) remained unchanged. The imbalance between these cellular activities appears to be responsible for the loss of trabecular bone mass. In proximal femoral metaphysis, measurements were performed in an area located under the muscular insertions. The trabecular bone volume, despite a slight decrease in flight rats, was not significantly different from that of control rats. Furthermore, osteoclastic and osteoid parameters were unchanged. Differential responses between these two long bones need additional investigations. In thoracic and lumbar vertebrae no detectable change in bone mass and bone resorption parameters was found.

Animals↗

PubMed1987

Effects of weightlessness on bone mass and osteoclast number in pregnant rats after a five-day spaceflight (COSMOS 1514).

Five pregnant growing rats were orbited for 5 days aboard the Soviet COSMOS 1514 biologic satellite. The bone effects of weightlessness were studied and compared to those of five pregnant rats kept in vivarium and five pregnant conditioned rats. Bone histomorphometric studies were performed to investigate the early effects of weightlessness in loaded (tibia-femur) and unloaded (thoracic and lumbar vertebrae) bones. A short exposure to weightlessness does not induce any change in bone mass and inner structure in either type of bone. In unloaded bones, the number of osteoclasts per square millimeter of the trabecular surface significantly increased when measured after histochemical demonstration of tartrate-resistant acid phosphatase. It is likely that a stimulation of bone resorption activity occurs in the trabeculae of unloaded bones during the early phase of a spaceflight. In tibia, osteoid seam thickness and total osteoclastic resorption surfaces at the endosteal level were not modified.

Acid Phosphatase↗