To determine the characteristics of magnetic resonance (MR) signals of normal growing cartilage and identify the difference in transverse relaxation times between physeal and epiphyseal cartilage in vivo. 24 distal femora of 12 two-week-old piglets were imaged on a 1.5 Tesla GE MR scanner. Comparison was made between signal intensity on MR images and the structure shown in corresponding histologic sections. T2 values were measured in eight piglets by means of multiecho spin-echo sequences. Our results showed that MR imaging delineated five regions between the secondary ossification center and the metaphysis, which histologically correspond to the zone of provisional calcification of the secondary ossification center, physis of the secondary ossification center, epiphyseal cartilage, physis and zone of provisional calcification. The T2 value in the physeal cartilage was much larger than that in the epiphyseal cartilage (P<0.05). It is concluded that MRI findings could differentiate the different regions of growing cartilage. T2 is longer in physeal than in epiphyseal cartilage, perhaps reflecting differences in water binding by proteoglycans.
Animals, Newborn ; Femur/anatomy & histology ; Femur/growth & development ; Femur/metabolism ; Growth Plate/*anatomy & histology ; Growth Plate/*growth & development ; Growth Plate/metabolism ; *Magnetic Resonance Imaging ; Osteogenesis/physiology ; Swine

BACKGROUND: Compressive force across the growth plate may cause retardation and even arrest of physeal growth. The purpose of this study was to investigate histologic changes, metabolic changes in terms of glycosaminoglycan (GAG) concentration, and contrast-enhanced micro-computed tomography (CEMCT) findings of physeal cartilage in a rabbit model of physeal damage caused by excessive compression. METHODS: Compressive forces were applied via external fixators for two weeks to the growth plates of distal femurs and proximal tibiae of right hind-legs in 8-week-old rabbits. Left hind-legs remained intact and were used as controls. Forty-four bone specimens containing growth plates of distal femurs or proximal tibiae were harvested one week (n = 12) and four weeks (n = 32) after surgery, and examined for histologic findings (H&E staining) and GAGs quantification in physeal cartilage. After incubation in an ionic contrast material for 48 hours, specimens were scanned by CEMCT, and the pixel values of physeal cartilage were measured. RESULTS: CEMCT showed a thin, highly attenuated line parallel to the growth plate in compressed specimens harvested at four weeks after surgery, which was found to be transversely connected trabecular bone. In these specimens, GAG content in physeal cartilage was significantly lower, and CEMCT pixel values of physeal cartilage were significantly higher than in the specimens from the contralateral control side. CONCLUSIONS: Excessive compressive force applied to growth plates produces altered histologic features and metabolic function in terms of decreased GAG content in physeal cartilage, changes that can be demonstrated by CEMCT.
Animals ; Growth Plate/*growth & development/metabolism/*pathology/radiography ; Male ; Pressure ; Rabbits ; X-Ray Microtomography

Bisphosphonates inhibit bone resorption by affecting osteoclastic function and formation of osteoclasts from their precursor cells. Chondroclasts have the same origin and differentiation as osteoclasts. Thus, it is hypothesized that bisphosphonate can affect on cartilage metabolism. This study was aimed to elucidate effects of alendronate, a nitrogen containing bisphosphonate, on cartilage development in the tibial proximal and femoral distal epiphyseal plates in rats. Alendronate (1 mg/kg) was subcutaneously administered in growing rat pups for 10 days. Several parameters such as the number and size of chondroclasts, involved in cartilage resorption, size of secondary ossification center and thickness of cartilage cell layers were measured and analysed by histomorphometry. The size of the secondary ossification centers in the tibial proximal and femoral distal epiphysis was smaller in the alendronate treated group (p< 0.01). The number of osteoclasts in the both the ossification centers and chondroclasts beneath the epiphyseal plates was significantly decreased by alendronate treatment (p< 0.01). The size of chondroclasts was not significantly changed (p> 0.05). The thickness of proliferating cartilage layer was not changed, but by contrast, hypertrophied cartilage layer was increased in thickness by alendronate treatment. These findings suggest that bisphosphonates can affect cartilage cell metabolism in a chondroprotective way.
Alendronate ; Animals ; Bone Resorption ; Cartilage ; Diphosphonates ; Epiphyses ; Growth Plate* ; Knee Joint* ; Knee* ; Metabolism ; Nitrogen ; Osteoclasts ; Rats*

To determine the characteristics of magnetic resonance (MR) signals of normal growing cartilage and identify the difference in transverse relaxation times between physeal and epiphyseal cartilage in vivo. 24 distal femora of 12 two-week-old piglets were imaged on a 1.5 Tesla GE MR scanner. Comparison was made between signal intensity on MR images and the structure shown in corresponding histologic sections. T2 values were measured in eight piglets by means of multiecho spin-echo sequences. Our results showed that MR imaging delineated five regions between the secondary ossification center and the metaphysis, which histologically correspond to the zone of provisional calcification of the secondary ossification center, physis of the secondary ossification center, epiphyseal cartilage, physis and zone of provisional calcification. The T2 value in the physeal cartilage was much larger than that in the epiphyseal cartilage (P<0.05). It is concluded that MRI findings could differentiate the different regions of growing cartilage. T2 is longer in physeal than in epiphyseal cartilage, perhaps reflecting differences in water binding by proteoglycans.
Animals ; Animals, Newborn ; Femur ; anatomy & histology ; growth & development ; metabolism ; Growth Plate ; anatomy & histology ; growth & development ; metabolism ; Magnetic Resonance Imaging ; Osteogenesis ; physiology ; Swine

The L-gulono-gamma-lactone oxidase gene (Gulo) encodes an essential enzyme in the synthesis of ascorbic acid from glucose. On the basis of previous findings of bone abnormalities in Gulo-/- mice under conditions of ascorbic acid insufficiency, we investigated the effect of ascorbic acid insufficiency on factors related to bone metabolism in Gulo-/- mice. Four groups of mice were raised for 4 weeks under differing conditions of ascorbic acid insufficiency, namely, wild type; ascorbic acid-sufficient Gulo-/- mice, 3-week ascorbic acid-insufficient Gulo-/- mice, and 4-week ascorbic acid-insufficient Gulo-/- mice. Four weeks of ascorbic acid insufficiency resulted in significant weight loss in Gulo-/- mice. Interestingly, average plasma osteocalcin levels were significantly decreased in Gulo-/- mice after 3 weeks of ascorbic acid insufficiency. In addition, the tibia weight in ascorbic acid-sufficient Gulo-/- mice was significantly higher than that in the other three groups. Moreover, significant decreases in trabecular bone volume near to the growth plate, as well as in trabecular bone attachment to the growth plate, were evident in 3- or 4-week ascorbic acid-insufficient Gulo-/-. In summary, ascorbic acid insufficiency in Gulo-/- mice results in severe defects in normal bone formation, which are closely related to a decrease in plasma osteocalcin levels.
Animals ; Ascorbic Acid* ; Down-Regulation* ; Glucose ; Growth Plate ; L-Gulonolactone Oxidase ; Metabolism ; Mice ; Osteocalcin* ; Osteogenesis* ; Plasma ; Tibia ; Weight Loss

PURPOSE: The aim of this study was to investigate the alterations of growth and bone metabolism in SDR induced by dexa administration and to evaluate the effects of GH treatment in dexamethasone(dexa) induced growth and bone metabolism in SDR. METHODS: Forty-five female Sprague-Dawley rats(weight 150-170gm) were divided in 3 groups: Group 1(n=15) received normal saline as control, Group 2(n=15) received dexa(1mg/kg/day), Group 3(n=15) received dexa and rhGH(LG Chem, 1IU/kg/day) simultaneously. Group 2 and 3 were injected rhGH daily, 6 days per week. Each group was divided in three subgroups(n=5) and sacrificed at 4, 6, 8 weeks, respectively. RESULTS: In Group 2, the length of tibia and femur and tibia epiphyseal plate thickness decreased significantly at 4, 6, 8 weeks compared to Group 1, respectively. In Group 2, serum IGF-I and PICP level also decreased at 6, 8 weeks and serum ICTP level increased at 4, 6 weeks compared to Group 1 significantly. In Group 3, the length of tibia and femur increased at 4, 6, 8 weeks compared to Group 2 but there was no statistical significance. In Group 3, tibia epiphyseal plate thickness increased significantly at 6, 8 weeks compared to Group 1. In Group 3, serum IGF-I and PICP level increased significantly at 4, 6, 8 weeks respectively compared to Group 2. But serum ICTP level showed no changes between two groups. Serum PTH level increased in Group 2 compared to Group 1, and decreased in Group 3 compared to Group 2 but no statistical significance was noted, respectively. CONCLUSION: Our data suggest that dexa inhibits longitudinal bone growth and interferes with bone metabolism, both inhibiting bone formation and stimulating bone resorption in SDR. Simultaneous GH administration may abolish alterations of growth and bone metabolism induced by dexa in SDR.
Animals ; Bone Density ; Bone Development ; Bone Resorption ; Dexamethasone* ; Female ; Femur ; Growth Hormone* ; Growth Plate ; Humans ; Insulin-Like Growth Factor I ; Metabolism* ; Osteogenesis ; Rats* ; Rats, Sprague-Dawley ; Tibia

PURPOSE: Pathologic changes in the growth plate remain unknown in Legg-Calve-Perthes (LCP) disease. Spontaneously hypertensive rats have proven to be a good model for studying LCP disease. This study investigated the histopathologic changes and the expression of vascular endothelial growth factor in the growth plate of spontaneously hypertensive rats (SHR). MATERIALS AND METHODS: Sixty SHR rats were divided into two groups: those showing osteonecrosis (SHR+n group: 32), and those showing normal ossification (SHR-n group: 28). Thirty Wister Kyoto rats served as a control. For histomorphological measurement, the length of each zone of the growth plate was measured. Cell kinetics was measured by 5-bromo-2'-deoxyuridin (BrdU) immunohistochemistry and transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assays. Vascular endothelial growth factor (VEGF) immunohistochemistry was used to identify of expression of VEGF. RESULTS: The lengths of growth plates of the SHR+n group were significantly shorter in the initial growth period than those of the other groups. The lowest proliferative rate and the highest apoptosis rate were observed in the SHR+n group at the initial growth period. The expression of VEGF in the growth plate of the SHR group was lower than the control group, and it was lower in the SHR+n group than in the SHR-n group. CONCLUSION: The growth plate of the SHR+n group was found to be affected by disease process of ischemic necrosis of the femoral head, and this might explain the relative overgrowth of the greater trochanter in the later stages of LCP disease.
Animals ; Apoptosis ; Femur Head/metabolism/*pathology ; Femur Head Necrosis/metabolism/pathology ; Growth Plate/*cytology/metabolism ; Osteogenesis/physiology ; Rats ; Rats, Inbred SHR ; Rats, Sprague-Dawley ; Vascular Endothelial Growth Factor A/metabolism

OBJECTIVETo observe the effects of Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine on vascular endothelial growth factor (VEGF) in growth retardation induced by Decamethasone and observe its mechanisms.

METHODSThirty one-month-old New Zealand white rabbits were randomly divided into normal group, dexamethasone-treated group and Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine-treated group. The rabbits in dexamethasone group and Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine-treated group received dexamethasone (5 mg/kg x d). The rabbits were sacrificed at the 6th and 12th week after administration, and then rabbit tibia articular was removed. (1) Using TUNEL stain to detect apoptotic index. (2) Using immunohistochemical stain to detect the positive index of the expression of vascular endothelial growth factor (VEGF) in the epiphyseal cartilage of growth. (3) Using fluorescent quantitative PCR to detect the expression intensity of VEGF mRNA in each group.

RESULTSAt the 6th and 12th week after administration, there were significant difference in apoptotic index and cell proliferation index between dexamethasone group and normal group (P<0.01, dexamethasone group more than normal group). Immunohistochemical stain and fluorescent quantitative PCR indicated that the expression of VEGF and VEGF mRNA in dexamethasone group was significantly decreased as compared with that in normal group (P<0.01), and also obviously lower than Chinese herbal medicine-treated group (P<0.01).

CONCLUSIONVEGF has 2. an important role during the growth retardation induced by Dexamethasone. Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine can reduce the growth retardation induced by Dexamethasone through increasing the VEGF expression in growth plate chondrocytes and then increase angiogenesis.

Animals ; Apoptosis ; Cell Proliferation ; Dexamethasone ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Female ; Gene Expression ; drug effects ; Growth Plate ; cytology ; drug effects ; growth & development ; metabolism ; Male ; Rabbits ; Random Allocation ; Vascular Endothelial Growth Factor A ; genetics ; metabolism

OBJECTIVETo observe the morphology and phenotypes of cells extracted from the endplate in the intervertebral discs and identify the factors affecting their biological characteristic.

METHODSThe intervertebral disc endplate were digested enzymatically, and the morphology of the obtained cells was examined under light microscope. Immunhistochemical analysis of collagen II and real-time PCR was carried out, and the morphologies, viability, cell growth, apoptosis and chondrocyte matrix production were compared between the cells isolated from the degenerative and normal vertebral endplates.

RESULTSThe cells in primary culture presented with spherical and oval morphology, and the cytoplasm was stained blue with toluidine blue. The morphologies of the cartilage endplate cells and the articular cells were almost identical. All the freshly isolated cells expressed collagen II. The degenerative vertebral endplate cells showed decreased expression of collagen II with increased apoptotic cells as compared with normal vertebral endplate cells.

CONCLUSIONThe intervertebral disc endplate cells, like articular cartilage cells, express cartilage-specific matrix proteins. Degenerative vertebral endplate cells show decreased cell vitality with increases cell apoptosis.

Adult ; Apoptosis ; physiology ; Cartilage ; metabolism ; pathology ; Cells, Cultured ; Chondrocytes ; metabolism ; pathology ; Collagen ; metabolism ; Female ; Growth Plate ; metabolism ; pathology ; Humans ; Intervertebral Disc ; metabolism ; pathology ; Intervertebral Disc Degeneration ; metabolism ; pathology ; Lumbar Vertebrae ; metabolism ; pathology ; Male ; Young Adult

"Rickets" is the term applied to impaired mineralization at epiphyseal growth plate, resulting in deformity and impaired linear growth of long bones. Rickets may arise as a result of vitamin D deficiency or abnormality in metabolism. Vitamin D-dependent rickets (VDDR) is rare autosomal recessive disorder in which affected individuals have clinical features of vitamin D deficiency. In 1961, Prader first described this disorder including severe clinical features of rickets, such as hypophosphatemia, hypocalcemia, muscle weakness and seizure. Two distinctive hereditary defects, type I VDDR and type II VDDR have been recognized in vitamin D metabolism. Type I VDDR may be due to congenital defects of renal 1 alpha-hydroxylase, the enzyme responsible for conversion of 25 (OH) D3. These patients have low to detectable 1,25(OH)2D3 in presence of normal to raised 25 (OH) D3. In type II VDDR, renal production of 1,25(OH)2D3 is intact but 1,25(OH)2D3 is not used effectively and target organ resistant to 1,25(OH)2D3 is respectively derived from the abnormality in the vitamin D receptor. We report a case of a 25 month-old girl with typical clinical features of VDDR type I rickets, hypocalcemia, increased alkaline phosphatase and secondary hyperparathyroidism.
Alkaline Phosphatase ; Child, Preschool ; Congenital Abnormalities ; Female ; Growth Plate ; Humans ; Hyperparathyroidism, Secondary ; Hypocalcemia ; Hypophosphatemia ; Metabolism ; Muscle Weakness ; Receptors, Calcitriol ; Rickets* ; Seizures ; Vitamin D ; Vitamin D Deficiency ; Vitamins*