Efficacy and safety of different doses of intravenous tissue plasminogen activator in Chinese patients with ischemic stroke.

Intravenous tissue plasminogen activator (tPA) at 0.9mg/kg improves outcome in acute ischemic stroke. The dose response to tPA may be different in Chinese patients compared with Western populations, but this has not been systematically examined. We aimed to compare the efficacy and safety of different doses of tPA in Chinese stroke patients. We included all acute ischemic stroke patients treated with tPA within 4.5 hours of onset. Patients were treated with three dose regimens of tPA (0.6-0.7mg/kg, 0.8mg/kg, 0.9mg/kg). The following data were collected: patient demographics; vascular risk factors; neuroimaging results; time of tPA administration; clinical assessment before treatment, at 24 hours and 3months; and modified Rankin Scale (mRS) score at 3months. A total of 105 patients with stroke of Han Chinese origin were included in the study. The baseline characteristics of the three dose groups were well matched. In the 0.9mg/kg group (n=51), 51.1% had favorable outcome at 3months, compared with 38.7% of patients in the 0.8mg/kg group (n=31) (odds ratio [OR] to 0.9mg/kg group, 0.57; 95% CI, 0.19-1.73; p=0.32) and 34.8% in the 0.6-0.7mg/kg group (n=23) (OR to 0.9mg/kg group, 0.31; 95% CI, 0.08-1.16; p=0.08). There were no statistically significant differences in the incidence of symptomatic intracerebral hemorrhage and mortality rate. There was a higher proportion of patients with good functional outcomes in the 0.9mg/kg group. Although not significant, these results strongly support the feasibility and urgent need for a dose ranging trial to establish an optimal tPA dose in Chinese stroke patients.

Enamel microhardness and bond strengths of self-etching primer adhesives.

The aim of this study was to determine the relationship between enamel surface microhardness and microshear bond strength (microSBS). Buccal and lingual mid-coronal enamel sections were prepared from 22 permanent human molars and divided into two groups, each comprising the buccal and lingual enamel from 11 teeth, to analyze two self-etching primer adhesives (Clearfil SE Bond and Tokuyama Bond Force). One-half of each enamel surface was tested using the Vickers hardness test with 10 indentations at 1 N and a 15-s dwell time. A hybrid resin composite was bonded to the other half of the enamel surface with the adhesive system assigned to the group. After 24 h of water storage of specimens at 37 degrees C, the microSBS test was carried out on a universal testing machine at a crosshead speed of 1 mm min(-1) until bond failure occurred. The mean microSBS was regressed on the mean Vickers hardness number (VHN) using a weighted regression analysis in order to explore the relationship between enamel hardness and microSBS. The weights used were the inverse of the variance of the microSBS means. Neither separate correlation analyses for each adhesive nor combined regression analyses showed a significant correlation between the VHN and the microSBS. These results suggest that the microSBS of the self-etch adhesive systems are not influenced by enamel surface microhardness.