Patella Alta and Trochlea Dysplasia Is Associated with Abnormal Type Ⅱ Collagen and Matrix Accumulation in Chondrocytes

The purpose of this study was to perform morphological and molecular analyses of articular cartilage from a 14-year-old boy with unusual cartilage lesions, patella alta and trochlea dysplasia in both knee joints and clinically examine two family members (sister, mother), also affected in their knee joints. Biopsies from the boy’s patella were used for: histological examination, Transmission Electron Microscopy (TEM) and DNA sequencing of the COL2A1 gene including Multiplex Ligation-dependent Probe Amplification (MLPA), for detection of DNA deletions and duplications. Clinical and radiological examination showed patella alta and trochlea dysplasia for the brother (type D), sister (type A) and mother (type A) with Insall-Salvati ratios of 1.50, 1.46 and 1.3. Light Microscopy (LM) of biopsies from the patient showed rhomboid chondrocytes in lacuna with deposition of protein aggregates in the ECM. TEM revealed abnormal type II collagen fibrils in aggregates and chondrocytes with abnormal matrix accumulation in rough Endoplasmic Reticulum (rER). Immunostaining showed that type II collagen was deposited intracellularly and in protein aggregates, together with type I collagen, indicating alterations in chondrocyte function and turnover of these molecules. DNA sequencing of 54 exons including extended DNA analysis with MLPA was non-conclusive. Conclusions: We suggest that patella alta and trochlea dysplasia for this patient is associated with collagen accumulation in chondrocytes, abnormal type II collagen heterofibrils in the ECM, cell death and cartilage with subnormal strength and increased risk of premature patellofemoral arthritis. A family with these disorders suggests that phenotype might be transmitted as an autosomal dominant trait.

Improvement of the matrix and the interface quality of a Cu/Al composite by the MARB process

The matrix accumulative roll bonding technology （MARB） can improve the matrix performance of metal composite and strengthen the bonding quality of the interface./n this research, for the fwst time, the technology of MARB was proposed. A sound Cu/AI bonding composite was obtained using the MARB process and the bonding characteristic of the interface was studied using scanning electricity microscope （SEM） and energy-dispersive spectroscopy （EDS）. The result indicated that accumulation cycles and diffusion annealing temperature were the most important factors for fabricating a Cu/AI composite material. The substrate aluminum was strengthened by MARB, and a high quality Cu/AI composite with sound interface was obtained as well.