Ligamentum teres reconstruction using autogenous semitendinosus tendon with toggle technique in rabbits.

Background: Ligamentum teres (LT) has traditionally been considered a vestigial or redundant structure in humans; however, based on new studies and the evolution of hip arthroscopy, the LT injury has been viewed as a source of hip pain. Therefore, LT reconstruction can be beneficial in some cases. Rabbits have been frequently used as a model for cranial cruciate ligament reconstruction but few studies are available for ligamentum teres reconstruction. Objective: To evaluate the semitendinosus tendon to replace ligamentum teres with the toggle technique, using rabbits as an experimental model. Methods: Twenty-six female Norfolk rabbits with approximately 3 months of age were divided into two equal groups after excision of ligamentum teres (LT) from the right hip joint: G1-no reconstruction of LT and capsulorrhaphy; G2-double-bundle reconstruction of the LT using semitendinosus tendon autograft. In both groups, the LT was removed from the right hip joint. In G2 the autograft was harvested from the left hind limb of the same rabbit. The rabbits were evaluated clinically at different time intervals; before surgery (M1), 48 h (M2), 15 days (M3), 30 days (M4) and 90 days (M5) after surgery. Results: The rabbits supported their limbs on the ground in both the groups. As complications of the procedure, four hip joints showed subluxations in the radiographic evaluation of G1; three at M4 and one at M5. In G2; two luxations of hip joints at M3 and one subluxation at M4 were seen. On ultrasound, irregular articular surface was seen in 30.8% of the rabbits that had subluxation of hip joints. Gross evaluation identified tendon graft integrity in 76.92% of the rabbits. Histological analysis revealed graft adhesion to the bone in the early phase comprised of sharpey-like collagen fibers. Conclusion: The double-bundle reconstruction of the LT using autologous semitendinosus tendon associated with the toggle rod shows an early phase of tendon graft ligamentization at 90 days post-operatively in young rabbits, but biomechanical bias suffered by the tendon during gait must be considered.

Mechanisms of Resistance to Chemotherapy in Breast Cancer and Possible Targets in Drug Delivery Systems.

Breast cancer (BC) is one of the most important cancers worldwide, and usually, chemotherapy can be used in an integrative approach. Usually, chemotherapy treatment is performed in association with surgery, radiation or hormone therapy, providing an increased outcome to patients. However, tumors can develop resistance to different drugs, progressing for a more aggressive phenotype. In this scenario, the use of nanocarriers could help to defeat tumor cell resistance, providing a new therapeutic perspective for patients. Thus, this systematic review aims to bring the molecular mechanisms involved in BC chemoresistance and extract from the previous literature information regarding the use of nanoparticles as potential treatment for chemoresistant breast cancer.

Prevalência da mutação causadora da paralisia periódica hipercalêmica em equinos da raça Quarto de Milha no Brasil / Prevalence of the hypercalemic periodic paralysis mutation in Quarter Horses in Brazil

A paralisia periódica hipercalêmica (HYPP) é uma das principais enfermidades genéticas de caráter dominante que acometem cavalos da raça Quarto de milha (QM). A HYPP é causada por uma mutação pontual no gene SCN4A e, apesar de estar presente nos cavalos QM no Brasil, dados sobre a prevalência da HYPP são escassos. O objetivo deste trabalho foi verificar a prevalência da mutação responsável pela HYPP em cavalos QM, utilizados nas modalidades esportivas de rédeas (n=160), apartação (n=160), tambor e baliza (n=160), corrida (n=160) e conformação (n=101). Foram utilizados DNA sanguíneo dos 741 equinos; o teste genético para enfermidade foi padronizado e as amostras sequenciadas para identificação da mutação no gene alvo. A prevalência de HYPP na população amostrada foi de 4,2%, sendo que somente na linhagem de conformação foram identificados animais positivos (30,7%). Medidas de controle mais efetivas devem ser adotadas para diminuir a prevalência da HYPP.

Hyperkalemic Periodic Paralysis (HYPP) is one of the major dominant genetic diseases which affect Quarter horses (QH). The HYPP is caused by a point mutation in the SCN4A gene and despite the presence of HYPP in Brazilian QH, limited data on the disease prevalence are available. The aim of this study was to investigate the HYPP mutation in QH belonging to reining (n=160), cutting (n=160), barrel racing (n=160), racing (n=160) and halter (n=101) competitive disciplines. Blood DNA from 741 horses were used. Genetic tests were standardized and samples were sequenced to identify the mutation on the target gene. The prevalence of HYPP on the sampled population was 4.2% and the positive animals (30.7%) were only identified in the halter lineage. More effective actions on HYPP control should be done to reduce the disease prevalence. .