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The objective of this study is to evaluate the influence of saline solution (0.9 per cent NaCl) on the tensile properties of freeze-stored tendons. Firstly, 170 pieces of chicken flexor digitorum profundus tendons were retrieved and wrapped in saline-soaked gauze before they were stored at -40degreesC. Then specimens were tensile tested at various time points over 360 days, scanning electron microscopy (SEM) was performed on fresh specimens, and specimens were freeze-stored for 233 days to investigate microstructure change after freeze storage. The mean values of strain ultimate tensile strength (UTS) did not deviate significantly (analysis of variance; p = 0.249) following freeze storage while the UTS and elastic modulus increased gradually with the duration of freeze storage and the growth became significant (p < 0.01) for durations longer than 70 and 40 days respectively. The SEM study showed that the collagen fibre density of specimens stored for 233 days decreased because of porosity growth. These findings suggested that the saline increased the tensile strength and modulus of the collagen.

The purpose of this study is to evaluate the effect of strain rate on the failure properties of tendons. Seventy-five chicken flexor digitorum profundus (FDP) tendons were tensile tested at 15 strain rates, ranging from 0.05 to 150 per cent/s. Results showed that strain rate had little effect on the shape of the stress-strain curve. No significant change was observed in the toe region, while the slope of the linear region increased with the increase in strain rate. Generally, the ultimate tensile strength (UTS) and elastic modulus increased significantly as strain rate increased (p < 0.01), while no significant change in strain at UTS (p > 0.01) was observed. It was found the change in failure properties of tendons was not significant, with small change in strain rate.

Purpose: Perfusion MR imaging offers an easy quantitative evaluation of relative regional cerebral blood volume (rrCBV), relative mean transit time (rMTT) and time-to-peak (TTP). The purpose of this study was to investigate the reliability of these parameters in assessing the hemodynamic disturbance of carotid occlusive disease in comparison with normative data., Material and Methods: Dynamic contrast-enhanced T2*-weighted perfusion MR imaging was performed in 19 patients with symptomatic unilateral internal carotid artery occlusion and 20 control subjects. The three parameters were calculated from the concentration-time curve fitted by gamma-variate function. Lesion-to-contralateral ratios of each parameter were compared between patients and control subjects., Results: Mean +/- SD of rrCBV, rMTT and TTP ratios of patients were 1.089 +/- 0.118, 1.054 +/- 0.031 and 1.062 +/- 0.039, respectively, and those of control subjects were 1.002 +/- 0.045, 1.000 +/- 0.006, 1.001 +/- 0.006, respectively. The rMTT and TTP ratios of all patients were greater than 2 SDs of control data, whereas in only 6 patients (32%), rrCBV ratios were greater than 2 SDs of control data. The three parameter ratios of the patients were significantly high compared with those of control subjects, respectively (p < 0.01 for rrCBV ratios, p < 0.0001 for rMTT ratios, and p < 0.0001 for TTP ratios)., Conclusion: Our results indicate that rMTT and TTP of patients, in contrast to rrCBV, are distributed in narrow ranges minimally overlapped with control data. The rMTT and TTP could be more reliable parameters than rrCBV in assessing the hemodynamic disturbance in carotid occlusive disease.

Purpose: To investigate the relationship between relative cerebral blood volume (CBV) measured with perfusion-weighted (PW) MR imaging and relative cerebral blood flow (CBF) measured with SPECT in acute ischemic stroke., Material and Methods: Fifteen patients who had acute unilateral middle cerebral artery occlusion underwent both PW MR imaging and 99mTc-HMPAO SPECT with an interval less than 20 min between the two examinations within 6 h after stroke onset. Lesion-to-contralateral relative CBV and CBF ratios measured in multiple regions of interest were compared to evaluate the relationship of the two parameters., Results: An overall linear relationship was found between relative CBV and relative CBF ratios (R2 = 0.54, p < 0.0001). The two parameters correlated linearly to each other in regions with evolving infarction (R2 = 0.43, p<0.0001), but not in regions without evolving infarction (R2 = 0.001, p>0.05). Regions with evolving infarction had more severe hypoperfusion (mean relative CBF ratio, 0.38 +/- 0.22) than regions without (mean relative CBF ratio, 0.70+/-0.13) (p<0.0001)., Conclusion: A significant linear relationship existed between relative CBV and relative CBF in acute ischemic stroke, although relative CBV did not change linearly to relative CBF in mild hypoperfusion. Relative CBV can be used as an alternative to relative CBF within 6 h after stroke onset, particularly in regions with severe hypoperfusion proceeding to infarction.