Various animal models have been used to investigate the normal and reparative properties of the knee meniscus. Yet, only limited data on meniscal biomechanical properties of various animals are available. It was therefore the objective of this study to compare measurements of meniscal biomechanical properties between six species: human, bovine, monkey, canine, sheep, and porcine. Uniaxial confined compression tests were conducted on 1-mm-thick, 4-mm-diameter meniscal discs, and the viscoelastic creep deformation was obtained. Two biomechanical parameters, the aggregate modulus (HA) and permeability (K), were found by implementing the linear biphasic theory and a newly developed nonlinear regression scheme. A one-way analysis of variance was conducted along with Student-Newman-Keuls comparison tests to assess the differences in these parameters among the species. Sheep menisci exhibited HA and K values most similar to human menisci. The water content of each specimen was also measured and correlated significantly with K. The interspecies variations found in material properties of the knee meniscus indicate the need for caution in extrapolating data on the biomechanical behavior of the human meniscus from animal models.
Although it has been reported that several growth factors modulate soft-tissue healing, the specific effects of growth factors on protein synthesis during ligament healing have not been widely investigated. In this study, we examined the effects of basic and acidic fibroblast growth factors, transforming growth factor beta 1, and epidermal growth factor on collagen and noncollagenous protein synthesis by cultured fibroblasts from medial collateral ligament and anterior cruciate ligament in vitro. Uptake of tritiated proline was used to measure synthesis of collagen and noncollagenous protein, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to analyze the type of collagens synthesized. Our data showed that transforming growth factor beta 1 increased both collagen and noncollagenous protein synthesis by medial collateral and anterior cruciate ligament fibroblasts on a dose-dependent basis. Collagen synthesis by cultured fibroblasts from the medial collateral and anterior cruciate ligaments was increased by treatment with transforming growth factor beta 1 by as much as approximately 1.5 times that of untreated controls. Although the response to transforming growth factor beta 1 by anterior cruciate ligament fibroblasts was equal to that by medial collateral ligament fibroblasts, the amounts of matrix proteins synthesized by anterior cruciate ligament fibroblasts were approximately half of that by medial collateral ligament fibroblasts. The increase was mostly in type-I collagen. Treatment of anterior cruciate ligament fibroblasts with epidermal growth factor increased collagen synthesis by approximately 25% but had little effect on medial collateral ligament fibroblasts. Neither basic nor acidic fibroblast growth factor increased either collagen or noncollagenous protein synthesis. These findings suggest that topical application of transforming growth factor beta 1, alone or in combination with epidermal growth factor, may have the potential to strengthen the ligament by increasing matrix synthesis during its remodeling and healing processes.
Although mechanical stress as a result of spinal instability is known to cause hypertrophy of the ligameiitum flavum resulting in degenerative spinal canal stenosis, the mechanism of the ligament hypertrophy is not well understood. In the present study, we investigated the effect of mechanical stretching force on collagen synthesis and transforming growth factor-/3 1 (TGF-PI) production using ligament cells isolated from human ligamentum flavum in vitro. Ligamenturn flavum cells (LFCs) were isolated from human ligamenturn flavum obtained from patients who underwent lumbar spine surgery. The LFCs were subjected to a mechanical stretching force using a cominercially available stretching device that physically deformed the cells. Collagen synthesis and TGF-PI production levels in the LFCs were then examined. Notable increases were observed in the gene expressions of collagen types I, 111, and V in LFCs subjected to mechanical stretching force. The increase in collagen gene expression of LFCs was inhibited in the presence of anti-TGF-pl antibodies. Production of TGF-PI by the LFCs also increased significantly by the mechanical stretching force. Exogenous application of TGF-PI was confirmed to increase collagen synthesis of the LFCs. This data indicated that mechanical stretching force can promote TGF-Dl production by LFCs, resulting in hypertrophy of the ligament.
We retrospectively reviewed fine-needle aspiration biopsy (FNAB) specimens of 301 soft tissue lesions of the extremities and trunk. Final diagnoses were 137 benign and 86 malignant neoplasms and 78 nonneoplastic lesions. Of the 301 FNAB samples, 279 (93%) were adequate for cytologic diagnosis. The adequate FNAB specimens were initially grouped into three broad categories: benign (197 cases), malignant (57 cases), and suspicious for malignancy (25 cases). Sensitivity and specificity for diagnosis of a malignant lesion were 92% and 97%, respectively. The specimens were cytomorphologically classified into nine categories: small round (14 cases), spindle cell (77 cases), epithelioid/polygonal (16 cases), pleomorphic (29 cases), myxoid (19 cases), lipomatous (37 cases), epithelial (23 cases), inflammatory lesions (28 cases), and others (36 cases). Specific FNAB diagnoses were correct in 151 of 279 cases (54%) in combination with clinical and radiologic findings. FNAB is a valuable technique for the primary diagnosis of soft-tissue lesions.
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