We hypothesized that rates of myofibrillar and patellar tendon collagen synthesis would fall over time during disuse, the changes being accompanied in muscle by decreases in focal adhesion kinase (FAK) phosphorylation and in gene expression for proteolytic enzymes. We studied nine men (22 ± 4 years, BMI 24 ± 3 kg m −2 (means ± S.D.) who underwent unilateral lower leg suspension for 23 days; five were studied between 0 and 10 days and four between 10 and 21 days. Muscle and tendon biopsies were taken in the postabsorptive state at days 0, 10 and 21 for measurement of protein synthesis, gene expression and protein phosphorylation. Muscle cross-sectional area decreased by 5.2% at 14 days and 10.0% (both P < 0.001), at 23 days, i.e. 0.5% day −1 , whereas tendon dimensions were constant. Rates of myofibrillar protein synthesis fell (P < 0.01) from 0.047% h −1 at day 0 to 0.022% h −1 at 10 days without further changes. Tendon collagen synthetic rates also fell (P < 0.01), from 0.052 to 0.023% h −1 at 10 days and then to 0.010% h −1 at 21 days. FAK phosphorylation decreased 30% (P < 0.01) at 10 days. No changes occurred in the amounts/phosphorylation of PKB-P70s6k-mTOR pathway components. Expression of mRNA for MuRF-1 increased ∼3-fold at 10 days without changes in MAFbx or tripeptidyl peptidase II mRNA, but all decreased between 10 and 21 days. Thus, both myofibrillar and tendon protein synthetic rates show progressive decreases during 21 days of disuse; in muscle, this is accompanied by decreased phosphorylation of FAK, with no marked increases in genes for proteolytic enzymes.

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Fifty-eight patients suffering from achillodynia for a median of 12 months (range, 4-240 months) were analyzed using history, clinical findings, ultrasound findings, histopathology, and surgical outcome. Surgical criteria were daily pain or inability to perform sports activity and failure of nonoperative treatment. There were 34 men and 24 women, 31% (18 of 58 patients) of whom had no direct association with sports or vigorous physical activity. Ultrasonography was performed in all cases and showed low echogenous areas (N = 48), increased tendon diameter (N = 40), and/or peritendinous fluid (N = 11). Histopathological evaluation of tendon biopsies, obtained from regions showing pathology at surgery (N = 35), revealed altered fiber structure and arrangement, focal variations in cellularity, extracellular glycosaminoglycans, neovascularization, and/or hyalinization. In no case was inflammatory cell infiltration observed. At a median clinical follow-up of 25 months after surgery, symptoms were decreased in 86% of patients, and 76% had reached a higher activity level compared with the level before surgery. Complications occurred in 13% of operations. In conclusion, achillodynia is not always associated with excessive physical activity. Macroscopic pathologic tendons showed marked histopathologic changes, correlating well with ultrasound findings. Surgical treatment was beneficial in most cases, despite a relatively high complication rate. The etiology and reason for the lack of healing response to rest and nonoperative treatment are unclear.