Testicular biodistribution of 450 nm fluorescent latex particles after intramuscular injection in mice

The significant expansion in the use of nanoparticles and submicron particles during the last 20 years has led to increasing concern about their potential toxicity to humans and particularly their impact on male fertility. Currently, an insufficient number of studies have focused on the testicular biodistribution of particles. The aim of our study was to assess the distribution of 450 nm fluorescent particles in mouse testes after intramuscular injection. To this end, testes were removed from 5 groups of 3 mice each at 1 h (H1), 4 days (D4), 21 days (D21), 45 days (D45) and 90 days (D90) after the injection of 7.28 × 10⁹ particles in the tibialis anterior muscles of each mouse. We examined histological sections from these samples by epifluorescence microscopy and confocal microscopy and identified testicular biodistribution of a small number of particles in groups H1, D4, D21, D45 and D90. Using CD11b immunostaining, we showed that particles were not carried into the testis by macrophages. The intratesticular repartition of particles mainly followed testicular vascularization. Finally, we found some particles in seminiferous tubules but could not determine if the blood-testis barrier was crossed.

Abstract 2475: Design and development of combretastatin based unsymmetrical terphenyls as small molecule antimitotic agents

The microtubule system of the eukaryotic cell plays indispensable role in the process of separating duplicated chromosomes before the cell division. Due to this essential function, they have been an important target for the development of cancer therapeutics. Several natural products such as Taxol, Vinca alkaloids, colchicine and their synthetic analogues that target microtubules have been used to treat several malignancies. However, cancer cells develop resistance to several of these agents by altering drug transporters and signaling pathways. Recently, combretastatins (CA) a group of diarylstilbenes isolated originally from stem wood of the South African tree Combretum caffrum have received much attention due to their potent anticancer activity against wide variety of human cancers including those that are multidrug resistant. These molecules specifically bind to the colchicine-binding site of the tubulins and prevent their polymerization required for the mitotic tubule formation thus possesses anti-proliferative and antivascular activities. A water soluble disodium phosphate derivative of CA has shown promising results in clinical trials of several malignancies, thus stimulating significant interest in a variety of CA analogues. However, the cis configuration of CA favors to form thermodynamically more stable trans isomer during storage and administration, producing a dramatic reduction in both tubulin binding and antiproliferative activities. Considering these limitations, we designed and synthesized a series of 3′,4′,5′-trimethoxy-2-phenylbiphenyl derivatives as cis-restricted CA analogues and evaluated for their antiproliferative activity, inhibitory effects on tubulin polymerization, cell cycle effects and apoptosis induction. Moreover, we adopted a novel strategy to synthesize these low molecular weight unsymmetrical terphenyls by a new synthetic methodology using Suzuki coupling in a one pot operation without isolating the biaryls intermediate. A majority of these compounds demonstrated significant anti-proliferative activity against most of the cell lines tested including that are multi-drug resistant. Interestingly, some of these compounds elicited DNA damage response in a dose dependent manner. Specifically, the compounds with acetamido and acetyl functional groups exhibited significant inhibitory activities in tubulin polymerization and growth inhibition. Consistent with their FACS profiles, Immunocytochemistry and biochemical analysis revealed loss of intact microtubule structure, up regulation of cyclin B1 and aurora kinase B mRNA levels, corresponding to growth arrest in the G2/M. More importantly, our one pot synthesis strategy of unsymmetrical terphenyls of this structural class paves the way for design and development of novel anticancer agents.

Citation Format: Surendra Reddy Punganuru, Sadanandam Palle, Kaushlendra Tripathi, Komaraiah Palle. Design and development of combretastatin based unsymmetrical terphenyls as small molecule antimitotic agents. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2475. doi:10.1158/1538-7445.AM2013-2475

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.

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.

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.

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.

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)

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.

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)

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.

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.

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.

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.

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.

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.

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.

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.

Effects of a 120 day period of bed-rest on bone mass and bone cell activities in man: attempts at countermeasure

The effects of immobilization on bone mass and bone remodeling in patients with spinal cord injuries are known to simulate weightlessness-induced bone changes in astronauts. Nevertheless, immobilization has never been investigated using histomorphometric studies in healthy volunteers. Twenty healthy male volunteers participated in a '120 day bed-rest' experiment in the USSR. Bone biopsy cores of iliac crest were taken before and at the end of the period of bed-rest. The subjects were divided into five groups. Five subjects underwent a normal ambulatory life (control subjects); three subjects were placed on continuous bed-rest for 120 days (complete immobilization); four subjects were immobilized and underwent a controlled training program; four subjects were immobilized and received treatment with potassium diphosphonate (ethane-1,hydroxy-1,diphosphonate 900 mg/day, per os); and four subjects were immobilized and received diphosphonate plus physical exercise. Parameters of bone mass and bone cellular activities (osteoblastic formation and osteoclastic resorption) were measured using automatic and semi-automatic image analysis systems. Bone mass remained constant in each group. Cellular activity measurements showed that in completely immobilized men, the mineralization rate was lower than in controls without change in osteoid parameters; in contrast, osteoclastic parameters were increased. In immobilized men given the training program, bone formation was normal and bone resorption was increased. In immobilized men treated with diphosphonate, osteoid parameters and resorption activity were decreased. In immobilized men with diphosphonate plus training, the osteoid parameters and the resorption activity were reduced but to a lesser degree than in immobilized men with diphosphonate alone. Failure of bone loss in normal immobilized subjects differed from results found in paraplegic patients. However, a decrease in mineralization rate and an increase in bone resorption activity were found in both studies. Exercise stimulated bone resorption and diphosphonate inhibited the osteoclastic activity. These data emphasize the difficulties in finding good models to stimulate spaceflight conditions on earth. Comparative studies must be done using bone biopsies to determine more precisely the effects of weightlessness on the human skeleton.

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.

Bone embedding in pure methyl methacrylate at low temperature preserves enzyme activities

Pure Methyl Methacrylate (MMA), a widely used embedding medium for undecalcified bone studies, was polymerized at low temperature (4 degrees C). MMA was prepared by a new purification procedure yielding a absolutely anhydrous and catalysed resin. The redox system benzoyle peroxide/NN-Dimethylanilin was used as the catalyzer-initiator system providing free radicals for the MMA chemical polymerization. Since the reaction is inhibited at -20 degrees C, complete infiltration of blocks is achieved within 3 d. Polymerization took place at +4 degrees C. The method provides undecalcified bone sections suitable for histomorphometric analysis of osteoid tissue, tetracycline bone labeling and Tartrate Resistant Acid Phosphatase. Enzyme histochemistry was shown to be possible in pure MMA embedded bones, when this low temperature embedding was used.

Permanent preservation of whole alizarin red S skeletons by clearing and embedding in polyester resins

A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method.

Polyester wadding for specimen orientation during embedding in methacrylates

Polyester fibers are not dissolved by either glycol methacrylate or methyl methacrylate. Commercial polyester wadding is consequently an advantageous material to use in getting precise orientation of tissue specimens during embedding in methacrylates.