Effects of different concentrations of tetramethylpyrazine, an active constituent of Chinese herb, on human corneal epithelial cell damaged by hydrogen peroxide.

AIM: To discuss the effects of different concentrations of tetramethylpyrazine (TMP), an active constituent of Chinese herb, on damaged Shandong human corneal epithelial cell (SDHCEC) induced by hydrogen peroxide. METHODS: We detected the combined effects of TMP with concentrations ranging from 4 mg/mL to 0.03 mg/mL and 800 µM hydrogen peroxide on SDHCEC. The methyl thiazolyl tetrazolium (MTT) assay was processed at 3, 6 and 12h separately while the detection of cell apoptosis at 6h only by flow cytometry. RESULTS: The viability of SDHCEC with 0.5 mg/mL, 0.25 mg/mL, 0.125 mg/mL and 0.06 mg/mL TMP joint with 800 µM hydrogen peroxide at 3h and 6h was significantly higher than that with 800 µM hydrogen peroxide only, P<0.05. However, except 0.25 mg/mL, TMP with other concentrations joint with 800 µM hydrogen peroxide at 12h could not significantly inhibit decreased SDHCEC viability induced by 800 µM hydrogen peroxide. At 12h, TMP of 0.5 mg/mL, 0.25 mg/mL, 0.125 mg/mL and 0.06 mg/mL could significantly inhibit SDHCEC early apoptosis induced by 800 µM hydrogen peroxide, most remarkable at 0.25 mg/mL TMP, P<0.05. CONCLUSION: Our results suggested that hydrogen peroxide can induce apoptosis related damage to SDHCEC. TMP can protect SDHCEC from the damage, and the protective effects may be associated with its anti-apoptosis mechanism.

Comparison of the Schirmer I test with and without topical anesthesia for diagnosing dry eye.

AIM: To determine the value of Schirmer I test (S I t) without anesthesia and with topical anesthesia for diagnosing dry eye (DE). METHODS: Totally 220 eyes in 110 patients, male (44) and female (66), (39.56±12.67) years old diagnosed with DE were examined. S I t without anesthesia was performed firstly, and 15 minutes later, it was applied again in the same person after topical anesthesia with 0.5% proparacaine hydrochloride eye drops. The wetting strips counted <10mm per 5 minutes were defined positive, while ≤5mm per 5 minutes were defined strong positive. RESULTS: The wetting length in S I t after topical anesthesia was significantly lower than that in S I t without anesthesia (P<0.001). The positive rate and strong positive rate of S I t after topical anesthesia were significantly higher than that of S I t without anesthesia (P<0.001). The positive rate and strong positive rate of S I t without anesthesia and the strong positive rate of S I t after topical anesthesia in patients with aqueous-deficiency dry eye (ADDE) were significantly higher than those in total patients whereas those in patients with evaporative dry eye (EDE) were significantly lower than those in total patients (P<0.001). CONCLUSION: S I t after topical anesthesia with 0.5% proparacaine hydrochloride eye drops is more objective and reliable than that without anesthesia in reflecting the status of DE, and its diagnostic value in patients with ADDE was even higher, making itself a meaningful evidence for the diagnosis and treatment of DE.

Ganoderma spore lipid inhibits N-methyl-N-nitrosourea-induced retinal photoreceptor apoptosis in vivo.

The purpose of the present study was to investigate the effect of Ganoderma spores lipid (GSL) on Bax, Bcl-xl and Caspase-3 expression in damaged retina and to address the effect of GSL on photoreceptor cell lesions induced by N-methyl-N-nitrosourea (MNU). Thirty 50-day-old female Sprague-Dawley rats were divided randomly into five groups to detect the dose-response effect of GSL by electroretinogram (ERG) analysis. Four groups received different daily GSL doses (0.5, 1, 2 and 4 g/kg, respectively) and one control group received no treatment. Sixty rats were divided randomly into an untreated MNU model control group and the GSL treatment group. Retina tissue samples were obtained sequentially 0 h before and 1, 3, 7 and 10 d after MNU injection. Expressions of Bax, Bcl-xl and Caspase-3 were detected by RT-PCR and immunofluorescence assays, then photoreceptor cell apoptosis was confirmed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling (TUNEL) signals. GSL had a dose-response effect on retina ERG and reversed retinal photoreceptor damage induced by MNU. RT-PCR analysis demonstrated that transcription levels of Bax, Bcl-xl and Caspase-3 in MNU control group and GSL treatment group were all upregulated on 1 d (p < 0.01) and peaked on 3 d (p < 0.01) after MNU injection compared to before MNU injection. GSL treatment significantly decreased mRNA levels of Bax on 1, 3, 7 and 10 d vs. MNU group (all p < 0.01) and mRNA levels of Caspase-3 on 1, 3, 7 d (p < 0.01) and 10 d (p < 0.05) vs. MNU group. Bcl-xl was clearly upregulation on 1, 3, 7 and 10 d vs. MNU group (all p < 0.01). Expression ratios of Bax/Bcl-xl were raised after MNU injection on 1 and 3 d vs. 0 h before MNU (both p < 0.01), peaked on 3 d, then dropped after GSL treatment on 1, 3, 7 and 10 d vs. MNU group (all p < 0.01). Immunofluorescence assays showed GSL decreased Bax and Caspase-3 positive staining levels in retina and increased Bcl-xl level. TUNEL-positive cells were evoked only in the outer nuclear layer and peaked on 3 d in rats receiving MNU (p < 0.01 vs. 0 h before MNU). GSL administration decreased apoptosis levels significantly, and the apoptotic indexes (AIs) of the GSL group were lower than those of MNU group on 1 and 3 d (both p < 0.01). Taken together, these data suggest that GSL may regulate the expressions of Bax, Bcl-xl and Caspases-3, inhibiting MNU-induced rat photoreceptor cell apoptosis and protecting retinal function.