THE ROUND LIGAMENT IN DEVELOPMENTAL HIP DYSPLASIA: ARE ITS MECHANICAL AND HISTOLOGICAL PROPERTIES PRESERVED?

Introduction: During open surgical dislocated hip reduction, several anatomical structures, such as the round ligament, are approached. However, there is controversy over both the possibility of preserving the ligament and its functional importance. Materials and Methods: This experimental study used skeletally immature rabbits as a model for congenital hip dislocation. Thirty-six rabbits comprised the sample that was submitted to the round ligament analysis. The sample was stratified for analysis (biomechanics, zymography, histology, and immunohistochemistry). Statistical analysis compared the unstable side to the control side of each rabbit. Results: Biomechanical assays showed that the mean maximal strength of the round ligament on the unstable side was similar to that of the control side (p = 0.594), which was also the case with maximum deformation (p = 0.328). Histologically, there was a statistically significant increase in cellularity on the unstable side (p <0.001). Additionally, there was significantly greater collagen occupancy on the control side (p <0.001). Zymography revealed no significant difference in the amount of active metalloproteinase 2 (MMP-2) (p = 0.068). Conclusions: Although histological analysis found evidence of significant changes in the RL in unstable hips, there were no significant differences in zymography, and no changes were observed in biomechanical tests. Evidence Level V; Experimental study.

Introdução: Durante a redução cirúrgica aberta de luxação de quadril, várias estruturas anatômicas são abordadas, entre elas, o ligamento redondo. No entanto, há controvérsias quanto à possibilidade de preservação desse ligamento, bem como sua importância funcional. Materiais e Métodos: Este estudo experimental usou coelhos esqueleticamente imaturos como modelo de luxação congênita do quadril. Trinta e seis coelhos compuseram a amostra que foi submetida à análise do ligamento redondo. A amostra foi estratificada para análise (biomecânica, zimografia, histologia e imuno-histoquímica). A análise estatística comparou o lado instável com o lado controle de cada coelho. Resultados: Os ensaios biomecânicos mostraram que a força máxima média do ligamento redondo no lado instável era semelhante ao lado controle (p = 0,594), o que também ocorreu com a deformação máxima (p = 0,328). Em termos histológicos, houve um aumento estatisticamente significante da celularidade no lado instável (p < 0,001). Além disso, houve maior ocupação de colágeno no lado controle (p < 0,001). A zimografia não mostrou diferença significativa da quantidade de metaloproteinase 2 ativa (MMP-2) (p = 0,068). Conclusões: Embora a análise histológica tenha encontrado evidências de alterações significativas do LR nos quadris instáveis, não houve diferenças significativas na zimografia e não foram observadas alterações nos testes biomecânicos. Nível de evidência V; Estudo experimental.

The round ligament in developmental hip dysplasia: are its mechanical and histological properties preserved? / O ligamento redondo na displasia do desenvolvimento do quadril: suas propriedades mecânicas e histológicas são preservadas?

ABSTRACT Introduction During open surgical dislocated hip reduction, several anatomical structures, such as the round ligament, are approached. However, there is controversy over both the possibility of preserving the ligament and its functional importance. Materials and Methods This experimental study used skeletally immature rabbits as a model for congenital hip dislocation. Thirty-six rabbits comprised the sample that was submitted to the round ligament analysis. The sample was stratified for analysis (biomechanics, zymography, histology, and immunohistochemistry). Statistical analysis compared the unstable side to the control side of each rabbit. Results Biomechanical assays showed that the mean maximal strength of the round ligament on the unstable side was similar to that of the control side (p = 0.594), which was also the case with maximum deformation (p = 0.328). Histologically, there was a statistically significant increase in cellularity on the unstable side (p <0.001). Additionally, there was significantly greater collagen occupancy on the control side (p <0.001). Zymography revealed no significant difference in the amount of active metalloproteinase 2 (MMP-2) (p = 0.068). Conclusions Although histological analysis found evidence of significant changes in the RL in unstable hips, there were no significant differences in zymography, and no changes were observed in biomechanical tests. Evidence Level V; Experimental study.

RESUMO Introdução Durante a redução cirúrgica aberta de luxação de quadril, várias estruturas anatômicas são abordadas, entre elas, o ligamento redondo. No entanto, há controvérsias quanto à possibilidade de preservação desse ligamento, bem como sua importância funcional. Materiais e Métodos Este estudo experimental usou coelhos esqueleticamente imaturos como modelo de luxação congênita do quadril. Trinta e seis coelhos compuseram a amostra que foi submetida à análise do ligamento redondo. A amostra foi estratificada para análise (biomecânica, zimografia, histologia e imuno-histoquímica). A análise estatística comparou o lado instável com o lado controle de cada coelho. Resultados Os ensaios biomecânicos mostraram que a força máxima média do ligamento redondo no lado instável era semelhante ao lado controle (p = 0,594), o que também ocorreu com a deformação máxima (p = 0,328). Em termos histológicos, houve um aumento estatisticamente significante da celularidade no lado instável (p < 0,001). Além disso, houve maior ocupação de colágeno no lado controle (p < 0,001). A zimografia não mostrou diferença significativa da quantidade de metaloproteinase 2 ativa (MMP-2) (p = 0,068). Conclusões Embora a análise histológica tenha encontrado evidências de alterações significativas do LR nos quadris instáveis, não houve diferenças significativas na zimografia e não foram observadas alterações nos testes biomecânicos. Nível de evidência V; Estudo experimental.

Preventive training does not interfere with mRNA-encoding myosin and collagen expression during pulmonary arterial hypertension.

To gain insight on the impact of preventive exercise during pulmonary arterial hypertension (PAH), we evaluated the gene expression of myosins and gene-encoding proteins associated with the extracellular matrix remodeling of right hypertrophied ventricles. We used 32 male Wistar rats, separated in four groups: Sedentary Control (S, n = 8); Control with Training (T, n = 8); Sedentary with Pulmonary Arterial Hypertension (SPAH, n = 8); and Pulmonary Arterial Hypertension with Training (TPAH, n = 8). All rats underwent a two-week adaptation period; T and TPAH group rats then proceeded to an eight-week training period on a treadmill. At the beginning of the 11th week, S and T groups received an intraperitoneal injection of saline, and SPAH and TPAH groups received an injection of monocrotaline (60 mg/kg). Rats in the T and TPAH groups then continued with the training protocol until the 13th week. We assessed exercise capacity, echocardiography analysis, Fulton's index, cross-sectional areas of cardiomyocytes, collagen content and types, and fractal dimension (FD). Transcript abundance of myosins and extracellular matrix genes were estimated through reverse transcription-quantitative PCR (RT-qPCR). When compared to the SPAH group, the TPAH group showed increases in functional capacity and pulmonary artery acceleration time/pulmonary ejection time ratio and decreases in Fulton's index and cross-sectional areas of myocyte cells. However, preventive exercise did not induce alterations in col1a1 and myh7 gene expression. Our findings demonstrate that preventive exercise improved functional capacity, reduced cardiac hypertrophy, and attenuated PH development without interfering in mRNA-encoding myosin and collagen expression during PAH.

Long-term effects of developmental exposure to di-n-butyl-phthalate (DBP) on rat prostate: proliferative and inflammatory disorders and a possible role of androgens.

In the present study we evaluated the toxic effects on the male adult rat prostate of DBP exposure during fetal and lactational periods, because although many studies have addressed the influence of phthalates on the male reproductive system, only a few have discussed their possible effects on prostate development. Pregnant females were distributed into two experimental groups: Control (C) and Treated (T). The females of the T group received DBP (100mg/kg, by gavage) from gestation day 12 to postnatal day 21, while C rats received the vehicle (corn oil). In adulthood (90 days old), the animals were euthanized. The serum and testicular testosterone levels were measured. Ventral prostate was removed and weighed. Distal segment fragments of the ventral prostate were fixed and processed for histochemistry and immunohistochemistry to detect androgen receptor (AR) and Ki67 antigens. Protein extraction from ventral prostate fragments was performed for AR immunoblotting and Gelatin zymography for MMP-2 and MMP-9 (MMP, metalloproteinase). Stereological and histopathological analyses were also performed. Serum and testicular testosterone levels and prostate weight were comparable between groups. In the T group the relative proportions (%) of epithelial (C=32.86; T=42.04*) and stromal (C=21.61; T=27.88*) compartments were increased, while the luminal compartment was decreased (C=45.54; T=30.08*), *p<0.05. InT, disseminated inflammatory infiltrate in the stroma, associated or not with epithelial dysplasia and PIN (Prostatic Intraepithelial Neoplasia), was observed. Increases in AR expression, proliferation index and metalloproteinase 9 (MMP-9) activity were noted in T animals. In some T animals, collagen fibrils accumulated adjacent to the epithelium. As far as we are aware, this is the first report in the literature showing that phthalates could play a role in proliferative and inflammatory disorders of the rat prostate.