Inflammatory pseudotumor of the hip: a complication of arthroplasty to be recognized by the radiologist

AbstractSoft tissue complications following hip arthroplasty may occur either in cases of total hip arthroplasty or in hip resurfacing, a technique that has become popular in cases involving young patients. Both orthopedic and radiological literatures are now calling attention to these symptomatic periprosthetic soft tissue masses called inflammatory pseudotumors or aseptic lymphocytic vasculites-associated lesions. Pseudotumors are associated with pain, instability, neuropathy, and premature loosening of prosthetic components, frequently requiring early and difficult reoperation. Magnetic resonance imaging plays a relevant role in the evaluation of soft tissue changes in the painful hip after arthroplasty, ranging from early periprosthetic fluid collections to necrosis and more extensive tissue damage.

A NOVEL POLYACRYLAMIDE-BASED HYDROGEL CROSSLINKED WITH CELLULOSE ACETATE AND PREPARED BY PRECIPITATION POLYMERIZATION

The synthesis of polyacrylamide-cellulose acetate hydrogels by precipitation polymerization in acetone solution is reported herein. These hydrogels exhibit smaller swelling ratios and larger compression moduli than homo polyacrylamide hydrogels. For cellulose acetate concentrations above 20 wt.%, hydrogels with N,N'-methylenebisacrylamide as a crosslinker exhibit swelling ratios and compression moduli similar to those of the hydrogels without the crosslinker. A possible explanation for this behavior is that cellulose acetate crosslinks polyacrylamide via free-radical reaction. The hydrogels obtained without the N,N'-methylenebisacrylamide crosslinker exhibit compression moduli up to 1.7 MPa, making them suitable for tissue engineering applications such as cartilage replacement.

Condroma de laringe: apresentação atípica

The authors report a case of laryngeal chondroma , a rare benign larynx tumor in the cricoid and arytenoid cartilages. There are aproximately 250 cases previously described in literature. A male, 41 year-old patient, presented a severe and progressive dyspnea leading to tracheostomy. Direct microlaryngoscopy revealed arytenoid enlargement and subglottic stenosis and the endoscopical biopsy was inconclusive, since the tumor present a hard gnistency. We performed surgical excision by laringofissura and total resection of the tumor, with good result. The histopathological examination showed a chondroma with no malignance.

Effects of hyperprolactinemia and ovariectomy on the tibial epiphyseal growth plate and bone formation in mice

PURPOSE: To evaluate the effects of ovariectomy and the hyperprolactinemia procedure in the tibial epiphyseal growth plate of female mice.METHODS: In this study, the epiphyseal growth plate of ovariectomized (OVX) and/or rendered hyperprolactinemic female mice by 50 days of treatment with 200 μg metoclopramide (M) was evaluated morphologically, morphometrically and immuno-histochemically. Forty female and adult mice were divided into four groups according to treatment: V group - animals treated with saline solution; H group - hyperprolactinemic animals; Ovx/V group - ovariectomized animals and treated with saline solution; Ovx/H group - hyperprolactinemic and ovariectomized animals. After the treatment period, the animals were sacrificed, tibia was removed and fixed in 10% buffered formalin and decalcified in 10% formic acid. The material was immersed in paraffin and subjected to histological processing in paraffin. The sections were stained with Masson's trichrome and immunohistochemistry was carried out for the pro-apoptotic protein BCL-2. The images for the morphological and morphometric study were analyzed with the imaging program AxioVision 4.8 (Carl-Zeiss(r), Germany).RESULTS: The combination of hyperprolactinemia and the ovariectomy procedure decreased the number of resting chondrocytes 1.5-fold, the number of proliferative chondrocytes 1.8-fold; the percentage of resting cartilage 2.4-fold and the percentage of trabecular bone 2.1-fold, compared with respective control animals.CONCLUSION: The procedure of ovariectomy combined with the metoclopramide-induced hyperprolactinemia in female mice has showed marked bone degeneration due to significant decrease of cell proliferation in the epiphyseal growth plate and bone formation.

Character transformations and their functional significance as a key to the evolution of hystricognath Rodentia

Hystricognathi represent a monophyletic taxon within Rodentia. Since phylogenetically analyzed morphological systems are essential for revealing evolutionary processes, this study identifies evolutionary character transformations on the stem lineage of Hystricognathi as derived from the author's own work and the literature. Data so far indicate that evolutionary transformations in the rostral head region, the loss of tactile ability in the outer nasal skin and the mobile arrangement of the associated cartilage, were allied with a switch from omnivorous to herbivorous and fiber-rich nutrition. Additional character transformations in the skull assist in digesting such food. Structures associated with reproduction and placentation show a remarkable pro portion of derived character conditions: the chorioallantoic placenta has a ring-shaped organization and growth structure which optimizes the capacity for passive diffusion, a subplacenta occurred as a specialized region responsible for placental invasion and the inverted yolk sac facilitates substance exchange with the main placenta. Finally, precocial newborns evolved as a derived condition within Rodentia. All things considered, a mode of reproduction is indicated, which does not demand excessive additional energy intake by the mother and is in accordance with her low energetic diet. Hystricognathi possess major character transformations that represent prerequisites for their successful radiation at the time when more open ecosystems and grasslands evolved during Earth history. The analysis resulted in the reconstruction of a life-near picture of the hystricognath stem species pattern with high explanatory power in terms of changes in space and time and their interdependence with biodiversity.

Degenerative joint disease in cattle and buffaloes in the Amazon region: a retrospective study

A retrospective study of the epidemiological and clinic-pathological aspects of cattle and buffaloes with degenerative joint disease (DJD) was conducted in the state of Pará, Brazil. From 1999 to 2014, eleven cattle and 24 buffaloes were evaluated. All the treated animals with suspected DJD underwent a clinical examination of the musculoskeletal system. In seven cattle and eight buffaloes with clinical signs of the disease postmortem examination was performed. The common clinical signs observed in both species were chronic lameness, stiff gait, postural changes, audible crackles in the affected limb, prolonged recumbency, difficulty in getting up and progressive weight loss. The lesions observed at necropsy were: irregular articular surfaces, erosion of the articular cartilage and the underlying bone tissue, and proliferation of the periarticular bone tissue with formation of osteophytes. The most affected joints in cattle and buffaloes wereof the hind limb. In buffaloes, the main predisposing factor to the onset of DJD was phosphorus deficiency. In cattle, defects of the anatomical conformation of the hind limbs, chronic trauma due to the activities performed, such as semen collection, and advanced age possibly contributed to the emergence of the disease.

Insulin impairs the maturation of chondrocytes in vitro

The precise nature of hormones and growth factors directly responsible for cartilage maturation is still largely unclear. Since longitudinal bone growth occurs through endochondral bone formation, excess or deficiency of most hormones and growth factors strongly influences final adult height. The structure and composition of the cartilaginous extracellular matrix have a critical role in regulating the behavior of growth plate chondrocytes. Therefore, the maintenance of the three-dimensional cell-matrix interaction is necessary to study the influence of individual signaling molecules on chondrogenesis, cartilage maturation and calcification. To investigate the effects of insulin on both proliferation and induction of hypertrophy in chondrocytes in vitro we used high-density micromass cultures of chick embryonic limb mesenchymal cells. Culture medium was supplemented with 1% FCS + 60 ng/ml (0.01 µM) insulin and cultures were harvested at regular time points for later analysis. Proliferating cell nuclear antigen immunoreactivity was widely detected in insulin-treated cultures and persisted until day 21 and [³H]-thymidine uptake was highest on day 14. While apoptosis increased in control cultures as a function of culture time, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-labeled cells were markedly reduced in the presence of insulin. Type II collagen production, alkaline phosphatase activity and cell size were also lower in insulin-treated cultures. Our results indicate that under the influence of 60 ng/ml insulin, chick chondrocytes maintain their proliferative potential but do not become hypertrophic, suggesting that insulin can affect the regulation of chondrocyte maturation and hypertrophy, possibly through an antiapoptotic effect.

Radiography, computed tomography and magnetic resonance imaging at 0.5 Tesla of mechanically inducedosteoarthritis in rabbit knees

In the present experimental study we assessed induced osteoarthritis data in rabbits, compared three diagnostic methods, i.e., radiography (XR), computed tomography (CT) and magnetic resonance imaging (MRI), and correlated the imaging findings with those obtained by macroscopic evaluation. Ten young female rabbits of the Norfolk breed were used. Seven rabbits had the right knee immobilized in extension for a period of 12 weeks (immobilized group), and three others did not have a limb immobilized and were maintained under the same conditions (control group). Alterations observed by XR, CT and MRI after the period of immobilization were osteophytes, osteochondral lesions, increase and decrease of joint space, all of them present both in the immobilized and non-immobilized contralateral limbs. However, a significantly higher score was obtained for the immobilized limbs (XT: P = 0.016, CT: P = 0.031, MRI: P = 0.0156). All imaging methods were able to detect osteoarthritis changes after the 12 weeks of immobilization. Macroscopic evaluation identified increased thickening of joint capsule, proliferative and connective tissue in the femoropatellar joint, and irregularities of articular cartilage, especially in immobilized knees. The differences among XR, CT and MRI were not statistically significant for the immobilized knees. However, MRI using a 0.5 Tesla scanner was statistically different from CT and XR for the non-immobilized contralateral knees. We conclude that the three methods detected osteoarthritis lesions in rabbit knees, but MRI was less sensitive than XR and CT in detecting lesions compatible with initial osteoarthritis. Since none of the techniques revealed all the lesions, it is important to use all methods to establish an accurate diagnosis.

RANK, RANKL and osteoprotegerin in arthritic bone loss

Rheumatoid arthritis is characterized by the presence of inflammatory synovitis and destruction of joint cartilage and bone. Tissue proteinases released by synovia, chondrocytes and pannus can cause cartilage destruction and cytokine-activated osteoclasts have been implicated in bone erosions. Rheumatoid arthritis synovial tissues produce a variety of cytokines and growth factors that induce monocyte differentiation to osteoclasts and their proliferation, activation and longer survival in tissues. More recently, a major role in bone erosion has been attributed to the receptor activator of nuclear factor kappa B ligand (RANKL) released by activated lymphocytes and osteoblasts. In fact, osteoclasts are markedly activated after RANKL binding to the cognate RANK expressed on the surface of these cells. RANKL expression can be upregulated by bone-resorbing factors such as glucocorticoids, vitamin D3, interleukin 1 (IL-1), IL-6, IL-11, IL-17, tumor necrosis factor-alpha, prostaglandin E2, or parathyroid hormone-related peptide. Supporting this idea, inhibition of RANKL by osteoprotegerin, a natural soluble RANKL receptor, prevents bone loss in experimental models. Tumor growth factor-ß released from bone during active bone resorption has been suggested as one feedback mechanism for upregulating osteoprotegerin and estrogen can increase its production on osteoblasts. Modulation of these systems provides the opportunity to inhibit bone loss and deformity in chronic arthritis.

Bone morphogenetic proteins: from structure to clinical use

Bone morphogenetic proteins (BMPs) are multi-functional growth factors belonging to the transforming growth factor ß superfamily. Family members are expressed during limb development, endochondral ossification, early fracture, and cartilage repair. The activity of BMPs was first identified in the 1960s but the proteins responsible for bone induction were unknown until the purification and cloning of human BMPs in the 1980s. To date, about 15 BMP family members have been identified and characterized. The signal triggered by BMPs is transduced through serine/threonine kinase receptors, type I and II subtypes. Three type I receptors have been shown to bind BMP ligands, namely: type IA and IB BMP receptors and type IA activin receptors. BMPs seem to be involved in the regulation of cell proliferation, survival, differentiation and apoptosis, but their hallmark is their ability to induce bone, cartilage, ligament, and tendon formation at both heterotopic and orthotopic sites. This suggests that, in the future, they may play a major role in the treatment of bone diseases. Several animal studies have illustrated the potential of BMPs to enhance spinal fusion, repair critical-size defects, accelerate union, and heal articular cartilage lesions. Difficulties in producing and purifying BMPs from bone tissue have prompted the attempts made by several laboratories, including ours, to express these proteins in the recombinant form in heterologous systems. This review focuses on BMP structure, molecular mechanisms of action and significance and potential applications in medical, dental and veterinary practice for the treatment of cartilage and bone-related diseases.

Alloxan-induced diabetes delays repair in a rat model of closed tibial fracture

A closed fracture was performed on the left tibia of 3-month-old Wistar rats weighing 250 to 350 g that were either healthy (N = 24) or made diabetic with alloxan (N = 24) to investigate the effect of alloxan-induced diabetes on the course of bone fracture healing. Histomorphometric analysis of the fracture site was performed at 7, 14, 25, and 35 days. After 7 days, diabetic rats had significantly less cartilage (P = 0.045) and greater fibrous connective (P = 0.006) tissue formation at the fracture site compared to controls. In contrast, marked callus formation was seen in diabetic rats with significant osteogenesis (P = 0.011, P = 0.010, P = 0.010, respectively, for 14, 25, and 35 days) and chondrogenesis (P = 0.028, P = 0.033, P = 0.019) compared to controls. Radiographic analysis revealed a displaced fracture with poor bone fragment alignment and delayed consolidation at these times in the diabetic group. The levels of alkaline phosphatase were significantly higher in diabetic rats at 25 days (P = 0.009). These results suggest that the initial excessive formation of fibrous connective tissue associated with delay in chondrogenesis and osteogenesis may not provide suitable stability of the fractured site, contributing to the inappropriate alignment of fragments and an increase in the volume of callus in later stages of repair. The resulting displaced fracture in diabetic rats requires long periods for remodeling and complete bone consolidation.

Co-culture of chondrocytes and bone marrow mesenchymal stem cells in vitro enhances the expression of cartilaginous extracellular matrix components

Chondrocytes and bone marrow mesenchymal stem cells (BMSCs) are frequently used as seed cells in cartilage tissue engineering. In the present study, we determined if the co-culture of rabbit articular chondrocytes and BMSCs in vitro promotes the expression of cartilaginous extracellular matrix and, if so, what is the optimal ratio of the two cell types. Cultures of rabbit articular chondrocytes and BMSCs were expanded in vitro and then cultured individually or at a chondrocyte:BMSC ratio of 4:1, 2:1, 1:1, 1:2, 1:4 for 21 days and cultured in DMEM/F12. BMSCs were cultured in chondrogenic induction medium. Quantitative real-time RT-PCR and Western blot were used to evaluate gene expression. In the co-cultures, type II collagen and aggrecan expression increased on days 14 and 21. At the mRNA level, the expression of type II collagen and aggrecan on day 21 was much higher in the 4:1, 2:1, and 1:1 groups than in either the articular chondrocyte group or the induced BMSC group, and the best ratio of co-culture groups seems to be 2:1. Also on day 21, the expression of type II collagen and aggrecan proteins in the 2:1 group was much higher than in all other groups. The results demonstrate that the co-culture of rabbit chondrocytes and rabbit BMSCs at defined ratios can promote the expression of cartilaginous extracellular matrix. The optimal cell ratio appears to be 2:1 (chondrocytes:BMSCs). This approach has potential applications in cartilage tissue engineering since it provides a protocol for maintaining and promoting seed-cell differentiation and function.

Pamidronate for the treatment of osteoporosis secondary to chronic cholestatic liver disease in Wistar rats

Osteoporosis is a major complication of chronic cholestatic liver disease (CCLD). We evaluated the efficacy of using disodium pamidronate (1.0 mg/kg body weight) for the prevention (Pr) or treatment (Tr) of cholestasis-induced osteoporosis in male Wistar rats: sham-operated (Sham = 12); bile duct-ligated (Bi = 15); bile duct-ligated animals previously treated with pamidronate before and 1 month after surgery (Pr = 9); bile duct-ligated animals treated with pamidronate 1 month after surgery (Tr = 9). Rats were sacrificed 8 weeks after surgery. Immunohistochemical expression of IGF-I and GH receptor was determined in the proximal growth plate cartilage of the left tibia. Histomorphometric analysis was performed in the right tibia and the right femur was used for biomechanical analysis. Bone material volume over tissue volume (BV/TV) was significantly affected by CCLD (Sham = 18.1 ± 3.2 vs Bi = 10.6 ± 2.2%) and pamidronate successfully increased bone volume. However, pamidronate administered in a preventive regimen presented no additional benefit on bone volume compared to secondary treatment (BV/TV: Pr = 39.4 ± 12.0; Tr = 41.2 ± 12.7%). Moreover, the force on the momentum of fracture was significantly reduced in Pr rats (Sham = 116.6 ± 23.0; Bi = 94.6 ± 33.8; Pr = 82.9 ± 22.8; Tr = 92.5 ± 29.5 N; P < 0.05, Sham vs Pr). Thus, CCLD had a significant impact on bone histomorphometric parameters and pamidronate was highly effective in increasing bone mass in CCLD; however, preventive therapy with pamidronate has no advantage regarding bone fragility.

Delivery of the Sox9 gene promotes chondrogenic differentiation of human umbilical cord blood-derived mesenchymal stem cells in an in vitro model

SRY-related high-mobility-group box 9 (Sox9) gene is a cartilage-specific transcription factor that plays essential roles in chondrocyte differentiation and cartilage formation. The aim of this study was to investigate the feasibility of genetic delivery of Sox9 to enhance chondrogenic differentiation of human umbilical cord blood-derived mesenchymal stem cells (hUC-MSCs). After they were isolated from human umbilical cord blood within 24 h after delivery of neonates, hUC-MSCs were untreated or transfected with a human Sox9-expressing plasmid or an empty vector. The cells were assessed for morphology and chondrogenic differentiation. The isolated cells with a fibroblast-like morphology in monolayer culture were positive for the MSC markers CD44, CD105, CD73, and CD90, but negative for the differentiation markers CD34, CD45, CD19, CD14, or major histocompatibility complex class II. Sox9 overexpression induced accumulation of sulfated proteoglycans, without altering the cellular morphology. Immunocytochemistry demonstrated that genetic delivery of Sox9 markedly enhanced the expression of aggrecan and type II collagen in hUC-MSCs compared with empty vector-transfected counterparts. Reverse transcription-polymerase chain reaction analysis further confirmed the elevation of aggrecan and type II collagen at the mRNA level in Sox9-transfected cells. Taken together, short-term Sox9 overexpression facilitates chondrogenesis of hUC-MSCs and may thus have potential implications in cartilage tissue engineering.