Improved procedure for histological identification of osteoid matrix in decalcified bone

Effect of experimental pulmonary arterial hypertension on renal and bone parameters of rats submitted to resistance exercise training

Pulmonary arterial hypertension (PAH) is characterized by right ventricular failure and diminished cardiac output, potentially leading to renal and bone impairments. In contrast, resistance exercise training (RT) offers cardiovascular and bone health benefits. This study aimed to assess the impacts of stable PAH induced by monocrotaline (MCT) and RT on renal morphometry, as well as bone morphometry and biomechanical properties in male Wistar rats. Four experimental groups, untrained control (UC, n=7), trained control (TC, n=7), untrained hypertensive (UH, n=7), trained hypertensive (TH, n=7), were defined. After the first MCT or saline injection (20 mg/kg), trained rats were submitted to a RT program (i.e., Ladder climbing), 5 times/week. Seven days later the rats received the second MCT or saline dose. After euthanasia, renal and femoral histomorphometry and femoral biomechanical properties were assessed. PAH reduced renal glomerular area and volume, which was prevented by the RT. While PAH did not harm the femoral morphometry, structural and mechanical properties, RT improved the femoral parameters (e.g., length, percentage of trabeculae and bone marrow, ultimte and yield loads). Experimental stable PAH promotes renal but not bone damages, whereas RT prevents renal deteriorations and improves the femoral morphological and biomechanical properties.

Disruption of collagen/apatite alignment impairs bone mechanical function in osteoblastic metastasis induced by prostate cancer

Prostate cancer (PCa) frequently metastasizes to the bone, generally inducing osteoblastic alterations that increase bone brittleness. Although there is growing interest in the management of the physical capability of patients with bone metastasis, the mechanism underlying the impairment of bone mechanical function remains unclear. The alignment of both collagen fibrils and biological apatite (BAp) c-axis, together with bone mineral density, is one of the strongest contributors to bone mechanical function. In this study, we analyzed the bone microstructure of the mouse femurs with and without PCa cell inoculation. Histological assessment revealed that the bone-forming pattern in the PCa-bearing bone was non-directional, resulting in a spongious structure, whereas that in the control bone was unidirectional and layer-by-layer, resulting in a compact lamellar structure. The degree of preferential alignment of collagen fibrils and BAp, which was evaluated by quantitative polarized microscopy and microbeam X-ray diffraction, respectively, were significantly lower in the PCa-bearing bone than in the control bone. Material parameters including Young's modulus and toughness, measured by the three-point bending test, were simultaneously decreased in the PCa-bearing bone. Specifically, there was a significant positive correlation between the degree of BAp c-axis orientation and Young's modulus. In conclusion, the impairment of mechanical function in the PCa-bearing bone is attributable to disruption of the anisotropic microstructure of bone in multiple phases. This is the first report demonstrating that cancer bone metastasis induces disruption of the collagen/BAp alignment in long bones, thereby impairing their mechanical function.

Nonproliferative and Proliferative Lesions of the Rat and Mouse Skeletal Tissues (Bones, Joints, and Teeth)

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) Project (www.toxpath.org/inhand.asp) is an initiative of the Societies of Toxicological Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in the skeletal tissues and teeth of laboratory rats and mice, with color photomicrographs illustrating examples of many common lesions. The standardized nomenclature presented in this document is also available on the internet (http://www.goreni.org/). Sources of material were databases from government, academic and industrial laboratories throughout the world.

Histopathological analysis for osteomalacia and tubulopathy in itai-itai disease

BACKGROUND & AIMS

Cadmium (Cd) is a widespread environmental contaminant that causes both renal tubulopathy and osteomalacia. Osteomalacia is thought to be a result of renal tubulopathy, but there are few studies about the histopathological relationship between the two pathoses. Therefore, in the present study, we examined specimens from cases of itai-itai disease (IID), the most severe form of chronic cadmium poisoning, to evaluate the relationship between them.

METHODS

We analyzed kidney and bone specimens of 61 IID cases and the data regarding Cd concentration in kidney and bone. Tubulopathy was graded on the basis of a three-step scale (mild, moderate, and severe) using the following three items: the degree of proximal tubular defluxion, thickness of renal cortex, and weight of the kidney. Osteomalacia was evaluated using the relative osteoid volume (ROV).

RESULTS

There were 15 cases of mild, 19 cases of moderate, and 27 cases of severe tubulopathy. The average ROV was 24.9 ± 2.0%. ROV tended to increase as tubulopathy advanced in severity, and ROV was significantly higher in cases with severe tubulopathy than those with mild or moderate tubulopathy. ROV had a negative correlation with Cd concentration in the kidney but no correlation with that in the bone.

CONCLUSIONS

Our results suggest that the development of osteomalacia was related to the development of tubulopathy.

Effect of Kami-kihi-to (Jia-Wei-Gui-Pi-Tang) for Experimental Osteopenia

In order to examine the effects of Kami-kihi-to (KKT or Jia-Wei-Gui-Pi-Tang) on osteopenia, we measured bone mineral density using computed X-ray absorptometry and monitored metabolism and bone tissue in an ovariectomized (OVX) rat model.

Bone mineral density was significantly lower in the OVX group than in normal group 3 months after ovariectomy. However, the bone mineral density of the OVX group administered KKT was clearly higher than that of the untreated OVX group.

Locomotor activity was regular in the normal group and in the OVX groups before administration of KKT. After 6-month administration of KKT, in OVX groups, the pattern of locomotor activity became diphasic with clear active and resting phases, as was also observed in the normal group. The locomotor activity did not decrease in the OVX groups after administration of KKT. At 6 months, the continuity of the trabecular bone was higher in the OVX group administered KKT than in the untreated OVX group. These results indicate that KKT improved the menopausal symptoms and increased the locomotor activity of the OVX group, thereby increasing bone mineral density.

A histochemical comparison of methylene-blue/acid fuchsin with hematoxylin and eosin for differentiating calcification of stromal tissue

Benign and malignant connective tissue tumors consist of a fibrous component that contains varying amounts of one or more types of bone or other calcified tissue. Diagnosis of these connective tissue tumors often poses challenges for pathologists, because it is difficult to differentiate the organic matrix of osteoid from hyalinized stroma. To establish a definitive diagnosis, it sometimes is advantageous to demonstrate histologically by special staining either the type of calcification or the presence or absence of calcification. We compared the efficacy of methylene blue-acid fuchsin (MB-AF) to hematoxylin and eosin (H-E) for connective tissue tumors suspected to contain calcifications and to devise an optimal staining technique for calcification that would be specific, simple, and cost- and time-effective. We examined 50 benign and 45 malignant connective tissue tumors that were suspected to contain calcifications. Sections were stained with H-E and MB-AF and evaluated. MB-AF stained bone pink, which contrasted with blue soft tissue. After MB-AF staining, osteoid was faint pink in a blue stromal background. Osteoid was not visualized in H-E stained sections; it was stained the same shade of pink as stromal tissue. Dystrophic calcification and cementum could be identified equally well using either staining technique, but contrast was better after H-E staining. MB-AF staining of bone was comparable to H-E staining and could be used effectively to stain bone and osteoid. MB-AF is a simple, single step procedure. It also stains cementum blue with faint blue rimming and dystrophic calcification bluish-pink, but it cannot be used as a specific stain for types of calcification other than bone and osteoid.

Intraosseous growth of human prostate cancer in implanted adult human bone: relationship of prostate cancer cells to osteoclasts in osteoblastic metastatic lesions

BACKGROUND

More than 80% of patients with advanced prostate cancer have skeletal involvement, but the biology of bone metastasis is poorly understood. This study investigated the in vivo formation and progression of bone metastases under conditions that resembled the human bone environment as closely as possible.

METHODS

Adult human bone fragments were implanted subcutaneously into 120 male NOD/SCID mice. Four weeks later, 1 x 10(7) LNCaP prostate cancer cells or phosphate-buffered saline were injected intravenously into 80 or 40 mice, respectively. The implanted bone fragments were removed from 20 to 10 mice in each group at 2, 4, 6, and 8 weeks after injection.

RESULTS

LNCaP colonized the bone marrow blood vessels within 2 weeks, and then gradually expanded into the entire medullary cavity. An osteoblastic response often occurred at the edges of metastatic foci (intertrabecular bone metaplasia). In addition, new bone formation was observed adjacent to mature lamellar bone (appositional bone formation). These two processes appeared to occur through different mechanisms, but might similarly cause osteosclerosis. Osteoclasts showed a marked increase in numbers at sites of early tumor invasion, whereas few osteoclasts were observed at sites where tumor invasion was complete.

CONCLUSIONS

The predominance of osteoblastic change with resorption may lead to bone remodeling in metastatic lesions, and osteoclasts may play an important role in bone metastasis from prostate cancer.

Prostate-specific antigen induces osteoplastic changes by an autonomous mechanism

The high prevalence of osteoplastic bone metastasis in prostate cancer (PC) is believed to be attributable to the production of osteoblast-stimulating factors by PC cells. Prostate-specific antigen (PSA) is a serine protease and an important serological marker for PC. Exposure of osteoblasts to PSA in vitro was found to result in cell proliferation and marked upregulation of transforming growth factor-beta (TGF-beta) mRNA expression. This PSA-induced increase in osteoblast proliferation was inhibited by anti-TGF-beta antibodies and serine protease inhibitors. In vivo, PSA markedly enhanced osteoplastic changes in human adult bone implanted into NOD/SCID mice without PC cells, and alpha(1)-antichymotrypsin prevented the PSA-induced increase in bone volume. PSA promotes osteoplastic change by activating an osteoblast autonomous mechanism that is independent of the production of bone growth factors by PC cells.

Cadmium induces osteomalacia mediated by proximal tubular atrophy and disturbances of phosphate reabsorption. A study of 11 autopsies

Osteomalacia of cadmium (Cd) poisoning (Itai-Itai disease) is induced by renal tubular dysfunction; however, the precise pathological changes and mechanisms have not been adequately elucidated. Of the 25 inhabitants in a Cd-polluted area who developed chronic tubular proteinuria, 22 individuals died over a 16-year period. Autopsies were performed in 11 cases and osteomalacia was detected in 9 cases (mean age at death 82.2 +/- 7.8 years; 1 man and 8 women). Histologically, osteomalacia occurred coincidentally with diffuse atrophy of the proximal tubules, moderate thickening of the tubular basement membrane and mild interstitial fibrosis in the renal cortex. Ultrastructurally, mitochondria in the proximal tubules were decreased in number and showed abnormal structure, while membrane enzymes, such as 5'-nucleotidase and ALPase, were still well preserved in their brush border. Glomeruli and distal tubules were minimally damaged. Severity of osteomalacia correlated with the damage of the proximal tubules as well as reduced serum calcium (Ca), serum Ca x phosphorus (P) and hematocrit, increased urine beta2-microglobulin, lysozymes, N-acetyl-b-D-glucosaminidase, retinol binding protein, creatinine, and reduced percent tubular reabsorption of phosphate. Multiple regression analysis showed that among these factors, serum Ca x P was an independent factor for predicting the severity of osteomalacia. Our findings suggest that osteomalacia by Cd poisoning causes degenerative changes in the proximal tubules, especially in mitochondria, which might affect the disturbance of the intracellular active transport energy system for calcium and phosphorus, resulting in osteomalacia.

Laser irradiation of bone: II. Healing response following treatment by CO2 and Nd:YAG lasers

BACKGROUND

Currently, the most commonly used lasers for dental procedures are the Nd:YAG and CO2. Studies comparing healing of osteotomy defects prepared with rotary burs to those created by laser irradiation have reported conflicting results. The purpose of this study was to evaluate and compare the histologic healing of bone in rat tibial osteotomy defects created either by a dental bur, CO2 laser with and without removal of the char layer, and Nd:YAG laser with char layer removed and with and without use of an air/water surface cooling spray.

METHODS

Tibial osteotomy defects were created in 4 groups of 6 rats each using the following: 1) #6 round bur with simultaneous saline irrigation; 2) CO2 laser with char layer intact; 3) CO2 laser with char layer removed; 4) Nd:YAG laser with air/water surface cooling, and char layer intact; 5) Nd:YAG laser with air/water surface cooling, and char layer removed; and 6) Nd:YAG laser without air/water surface cooling, and char layer removed. Both laser types were used at energy densities typically utilized for oral soft tissue surgery.

RESULTS

Progressive healing from day 0 through day 21 post-treatment was observed in all treatment groups. However, compared to controls treated by rotary dental bur, those specimens treated by laser, regardless of laser type, energy density, or other parameters, exhibited a delay in healing that appeared to be related to the presence of residual char in the osseous defect. Specimens treated with the Nd:YAG laser using an air/water surface coolant exhibited a decreased thickness and continuity of the char layer and yielded the only specimens with new bone formation at the surface of the laser ablation defect. In addition, the normal pattern of bone remodeling in the rat tibia appeared to have been altered by laser irradiation.

CONCLUSIONS

In this animal model, laser-induced osteotomy defects, when compared to those prepared by rotary bur, exhibited a delayed healing response that appeared to be related to the presence of residual char in the osseous defect.

Histomorphometric study of ribs with looser zones in Itai-itai disease

Twelve Looser zones and 17 healing bands of the ribs obtained from autopsy cases of Itai-itai disease were analyzed by bone histomorphometry. Furthermore, proper cancellous tissue of the ribs from 24 autopsy cases of Itai-itai disease with Looser zones or with the healing bands, 27 autopsy cases of Itai-itai disease without such lesions, and 29 control cases were studied by the same method to pursue the histogenesis of Looser zones. In translucent zones of Looser zones, 94% of the cancellous bone was occupied by thick woven bone in which 72% was woven osteoid and 22% was woven mineralized bone. In adjacent scleroses, 71% of the cancellous bone was occupied by woven bone in which 37% was woven mineralized bone, and 34% was woven osteoid; 53% of the cancellous bone consisted of mineralized bone. As compared with those in translucent zones, woven osteoid was decreased, and mineralized bone was increased significantly in the cancellous bone of adjacent scleroses. A significant increase of lamellar mineralized bone and a decrease of woven bone in healing bands were observed as compared with those in Looser zones. These findings suggest that the healing starts from the edge of the Looser zone, and slowly proceeds toward the center. In the cancellous bone of the ribs, the volume, thickness, and surface of osteoid and woven bone were significantly increased in patients with Itai-itai disease, with Looser zones as compared with those without Looser zones. It was concluded that Looser zones seem to occur in severe osteomalacic bones that contain abundant woven bone in the patients of Itai-itai disease.

Microgravity generated by space flight has little effect on the growth and development of chick embryonic bone

Seven days' space flight of fertilized chicken eggs pre- incubated for 7 and 10 days on earth caused no differences in the morphology of osteoblasts, osteoclasts, and osteocytes of humerus and tibia from those of control embryos. Bone-resorbing and -forming activities of the femur were not different between control and flight groups. As a consequence, calcium and phosphorus contents of the femora between control and flight groups were not changed. Alkaline phosphatase activity of 3 different regions (resting cartilage, growth cartilage, and cortical bone) of tibia showed no significant difference between control and flight groups. No significant difference of gene expressions of hepatocyte growth factor and receptors of fibroblast growth factor was observed in perichondrium, trabecula, and skeletal muscles and tendons of hind limbs between control and flight groups. Unlike the results of previous space flight experiments in which young growing mammals were used, these morphological and biochemical results indicate that microgravity has little effect on bone metabolism of the chick embryo.

Iron as a possible aggravating factor for osteopathy in itai-itai disease, a disease associated with chronic cadmium intoxication

Itai-itai disease is thought to be the result of chronic cadmium (Cd) intoxication. We examined 23 autopsy cases of itai-itai disease and 18 cases of sudden death as controls. Urine and blood samples from 10 patients were collected before they died and revealed the presence of severe anemia and renal tubular injuries. Undecalcified sections of iliac bone were stained with Aluminon reagent, and ammonium salt of aurintricarboxylic acid, and Prussian blue reagent in all cases of itai-itai disease. These two reagents reacted at the same mineralization fronts. X-ray microanalysis revealed the presence of iron at mineralization fronts in itai-itai disease. Five patients showed evidence of hemosiderosis in the liver, spleen, and pancreas, probably as a result of post transfusion iron overload. Renal calculi and calcified aortic walls were also stained with Prussian blue reagent in several patients. Neither ferritin nor transferrin were visualized at mineralization fronts in itai-itai disease by immunohistochemical staining. These results suggest that iron is bound to calcium or to calcium phosphate by a physicochemical reaction. A marked osteomalacia was observed in 10 cases of itai-itai disease by histomorphometry. Regression analyses of data from cases of itai-itai disease suggested that an Aluminon-positive metal inhibited mineralization and that renal tubules were injured. Since bone Cd levels were increased in itai-itai disease, it is likely that renal tubules were injured by exposure to Cd. Therefore, stainable bone iron is another possible aggravating factor for osteopathy in itai-itai disease, and a synergistic effect between iron and Cd on mineralization is proposed.

A quantitative study of iliac bone histopathology on 62 cases with itai-itai disease

Sixty-two autopsy cases with "itai-itai" or "ouch-ouch" (in English) disease and 50 control subjects were examined by static quantitative bone histopathology. Decalcified sections after cyanuric chloride treatment (Yoshiki's method) were used. The small observer variances of the decalcified sections guaranteed the accuracy and precision of this method. In the static measurement analyses, significant increases in formation parameters and decreases in structural parameters were observed (P less than 0.05-0.000001), suggesting the presence of a marked osteoid accumulation accompanied by a bone mass reduction. Discriminant analysis clearly separated the patients from the control subjects. Two-thirds of the patients showed an increase in resorption surface prior to osteoid deposition and a decrease in osteoblast surface. Double tetracycline labeling in 4 patients showed an impaired osteoid maturation and mineralization. An impaired osteoblastic function was suggested by the results of the static and dynamic histomorphometry. The bone cadmium contents were measured in 46 patients by an atomic absorption spectrophotometer and found to be increased significantly (P less than 0.01). In Aluminon (an ammonium salt of aurine tricarboxytic acid) staining, a clear, reddish line was located in an osteoid-bone interface, suggesting a reaction of Aluminon with tissue aluminium and/or cadmium. These results suggested that an impairment of osteoblastic function and mineralization occurred in itai-itai disease and that cadmium is a possible etiological factor.

Bone in the marmoset: a resemblance to vitamin D-dependent rickets, type II

The common marmoset, a New World monkey, requires a large amount of vitamin D3 to maintain its normal growth. This monkey is reported to have an end-organ resistance to 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3). In this study, the bone morphology of marmosets fed a high vitamin D3 diet (intake of vitamin D3, 110 IU/day/100 g of body weight) was compared by X-ray and histological examinations with that of rhesus monkeys (Old World monkey) fed a normal diet (intake of vitamin D3, 5 IU/day/100 g of body weight). Three of 20 marmosets were found by X-ray examination to have osteomalacic changes in their bones despite the high daily intake of vitamin D3, whereas none of the 5 rhesus monkeys showed any signs of osteomalacia. Osteomalacic marmosets had distinct increases in osteoid surface, relative osteoid volume, and active osteoclastic bone resorption, whereas non-osteomalacic marmosets had no increase in osteoid tissues in their bones. None of the marmosets, either osteomalacic or non-osteomalacic, was hypercalcemic despite the extremely high circulating levels of 1 alpha,25(OH)2D3. However, the serum 25-hydroxyvitamin D3 (25OHD3) and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) levels were significantly lower in the osteomalacic than in the non-osteomalacic marmosets. These results suggest that the marmoset is likely to exhibit osteomalacic bone changes despite the high daily intake of vitamin D3. These changes resemble those in vitamin D-dependent rickets, type II.

The role of vitamin D in the medullary bone formation in egg-laying Japanese quail and in immature male chicks treated with sex hormones

The effect of vitamin D3 on medullary bone formation was investigated in egg-laying Japanese quail and in immature male chicks treated with sex hormones. When laying quail were fed a vitamin D-deficient diet for 16 days, their eggshell weights and egg production rate were markedly reduced in a time-dependent manner with a significant decrease in plasma calcium and 25-hydroxyvitamin D3 levels. The calcium content of the medullary bone of femurs decreased markedly with the progress of vitamin D deficiency, whereas that of the cortical bone remained unchanged. Quantitative histological examination also showed that the area of the mineralized portion of medullary bone in quail that were fed the vitamin D-deficient diet markedly decreased compared with that in the control laying quail, whereas the total area of the mineralized and unmineralized portions of medullary bone in the bone marrow cavity increased moderately. Daily administration of vitamin D3 (0.75 microgram/day) to the vitamin D-deficient quail increased the mineralization of medullary bone as early as day 4. Daily administration of both estradiol (0.3 mg/day) and testosterone (0.9 mg/day) for 3 weeks to immature male chicks induced an apparent hypercalcemia and matrix formation of medullary bone, regardless of the vitamin D status of the chicks. Mineralization of medullary bone was observed only when vitamin D3 was administered together with the sex hormones. These results suggest that vitamin D3 is directly involved in the mineralization of medullary bone in birds.