Influence of acute and chronic streptozotocin-induced diabetes on the rat tendon extracellular matrix and mechanical properties.

Diabetes is a major risk factor for tendinopathy, and tendon abnormalities are common in diabetic patients. The purpose of the present study was to evaluate the effect of streptozotocin (60 mg/kg)-induced diabetes and insulin therapy on tendon mechanical and cellular properties. Sprague-Dawley rats (n = 40) were divided into the following four groups: nondiabetic (control), 1 wk of diabetes (acute), 10 wk of diabetes (chronic), and 10 wk of diabetes with insulin treatment (insulin). After 10 wk, Achilles tendon and tail fascicle mechanical properties were similar between groups (P > 0.05). Cell density in the Achilles tendon was greater in the chronic group compared with the control and acute groups (control group: 7.8 ± 0.5 cells/100 µm(2), acute group: 8.3 ± 0.4 cells/100 µm(2), chronic group: 10.9 ± 0.9 cells/100 µm(2), and insulin group: 9.2 ± 0.8 cells/100 µm(2), P < 0.05). The density of proliferating cells in the Achilles tendon was greater in the chronic group compared with all other groups (control group: 0.025 ± 0.009 cells/100 µm(2), acute group: 0.019 ± 0.005 cells/100 µm(2), chronic group: 0.067 ± 0.015, and insulin group: 0.004 ± 0.004 cells/100 µm(2), P < 0.05). Patellar tendon collagen content was ∼32% greater in the chronic and acute groups compared with the control or insulin groups (control group: 681 ± 63 µg collagen/mg dry wt, acute group: 938 ± 21 µg collagen/mg dry wt, chronic: 951 ± 52 µg collagen/mg dry wt, and insulin group: 596 ± 84 µg collagen/mg dry wt, P < 0.05). In contrast, patellar tendon hydroxylysyl pyridinoline cross linking and collagen fibril organization were unchanged by diabetes or insulin (P > 0.05). Our findings suggest that 10 wk of streptozotocin-induced diabetes does not alter rat tendon mechanical properties even with an increase in collagen content. Future studies could attempt to further address the mechanisms contributing to the increase in tendon problems noted in diabetic patients, especially since our data suggest that hyperglycemia per se does not alter tendon mechanical properties.

"Get a Grip on Hypertension": EXPLORING THE USE OF ISOMETRIC HANDGRIP TRAINING IN CARDIOPULMONARY REHABILITATION PATIENTS.

PURPOSE: Isometric handgrip (IHG) training lowers systolic and diastolic blood pressure (SBP and DBP, respectively), but the efficacy of IHG training in cardiopulmonary rehabilitation patients is unknown. The purpose of this study was to determine if IHG decreases blood pressure in cardiopulmonary rehabilitation patients. METHODS: Cardiopulmonary rehabilitation program participants (n = 11; 50-80 yr old) were randomized to IHG (n = 6) or control (CON; no treatment; n = 5) groups. IHG participants completed an IHG training program at 30% maximal voluntary contraction, 3 d/wk for 6 wk. Resting SBP, DBP, and heart rate were assessed weekly. RESULTS: Mean regression for SBP following IHG was negative (-1.04 ± 0.80). Mean regression in the CON group was positive (0.50 ± 0.88), but there was no significant difference between groups. Separate analysis of weeks 1 to 7 yielded a negative mean regression (-1.12 ± 0.54) in the IHG group, but positive (1.2 ± 0.60) in the CON group. A Wilcoxon test of these differences yielded significance for SBP (P = .009). In 3 of 6 IHG participants, SBP was lower (mean ± SD: -16 ± 11 mm Hg; P = .12), and in 2 IHG participants, DBP was lower (-9 ± 1 mm Hg; P = .06) compared with baseline. In 2 of 5 CON participants, SBP was not significantly lower (-11 ± 7 mm Hg) and, in 3 of 5 CON participants, DBP was lower (-7 ± 4 mm Hg; P = .04). CONCLUSIONS: Our data suggest that standard IHG training may be inadequate for blood pressure management immediately following a major cardiac or pulmonary event. Future work with a larger cohort and more developed training protocol to determine the efficacy of IHG training in patients with cardiopulmonary disease is warranted.