Albert Wingnang Leung

Cellular uptake, subcellular localization and photodamaging effect of Temoporfin (mTHPC) in nasopharyngeal carcinoma cells: comparison with hematoporphyrin derivative

Temoporfin (meta-tetra (hydroxyphenyl)chlorin; mTHPC) potentiated a 100-fold higher cytotoxic effect than hematoporphyrin derivative (HPD) on two nasopharyngeal carcinoma cell lines (HK1 and CNE2) in terms of the overall photodynamic therapy (PDT) dose. The cellular uptake, evaluated by flow cytometry and spectrophotometry demonstrated that mTHPC exhibited higher uptake ability than HPD. Confocal laser scanning microscopy detection for both the sensitizer and mitochondria probe on the same cell images revealed that both drugs accumulated diffusely in the cytoplasm and that mitochrondria is a target organelle. Photo-activation ruptured the mitochrondria, with more pronounced mitochondrial damage being observed in mTHPC-PDT course. This correlated well with the cell photokilling efficiency of mTHPC.

pH-responsive polymer-drug conjugates: Design and progress.

Polymer-drug conjugates are becoming established as a shining platform for drug delivery. Incorporation of pH-responsive linker between drug and polymer is expected to realize triggered release of bioactive agents from conjugates in specific sites, either in mildly acidic extracellular matrices of tumor tissues or, after cellular internalization, in acidic endosomes and lysosomes. As an emerging drug delivery system, such pH-responsive polymer-drug conjugates are able to selectively deliver and activate drug molecules while reducing their systemic side-effects. In this review, we present the recent advances in pH-responsive polymer-drug conjugates with different chemical structures and architectures, and attempt to clarify their mechanism of action, synthesis and characterization technology. Furthermore, several promising approaches for the future will also be suggested.

Redox changes precede the occurrence of oxidative stress in eyes and aorta, but not in kidneys of diabetic rats

Almost all diabetic complications are known to be associated with vascular dysfunctions of different tissues. Oxidative stress, on the other hand, has been implicated in the pathogenesis of diabetes mellitus. Therefore in the present study we have investigated the correlation between redox status and oxidative stress in the eyes, aorta and kidneys of streptozotocin (STZ)-induced diabetic rats. Glutathione (GSH), the primary endogenous antioxidant, and malondialdehyde (MDA), a marker of oxidative stress, were measured in these tissues of diabetic rats at different time points after STZ injection. Our results showed that GSH was reduced significantly in both the eyes and aorta of diabetic rats 8 weeks after STZ injection (43% and 66% of the control, respectively). Furthermore, the depletion of GSH occurred from the first week after STZ injection, and the level remained low as compared with the control rats (both week 1 and week 8: 43% and 66% of the control in the eyes and aorta, respectively). MDA was not increased until week 8 onwards after STZ-injection (177% and 93% of the control in the eyes and aorta, respectively). These changes, however, were not found in the kidneys, in which the GSH was slightly increased and MDA remained comparable to the control rats. These results indicate different tissues respond differently to high glucose conditions as redox changes and oxidative stress occurred only in the eyes and aorta but not in the kidneys of diabetic rats. In addition, the onset of oxidative stress is preceded by a depletion of GSH and probably an exhaustion of the antioxidant defense system. Furthermore, administration of Vitamin E was found to normalize MDA levels in the eyes and aorta but not in the kidneys of diabetic rats. In summary, our results suggest that the underlying mechanism in developing diabetic complications in the eyes and aorta involves the occurrence of oxidative stress, which may not be the case in diabetic kidneys. In addition, Vitamin E may prevent the development of diabetic complications in the eyes and aorta by reducing lipid peroxidation and oxidative damage in the cells.

Effectiveness of auricular therapy on sleep promotion in the elderly

Sleep disturbances are a particularly common problem in the elderly. The purpose of this study was to examine the effectiveness of auricular therapy on sleep behaviors in the elderly. One hundred and twenty participants of 60 years old or above and who were suffering from sleep disturbances were invited to participate in this study. Eligible participants were randomly allocated to receive auricular therapy using Junci Medulla (Group A = 30), Semen Vaccariae (Group B = 30) or magnetic pearls (Group C = 60). Groups A and B were the control groups, while Group C was the experimental group. Seven auricular points which are thought to have an effect on promoting sleep were selected. The total treatment course lasted for three weeks. Objective measurement using actigraphic monitoring was performed before the therapy commenced, in the middle period of the therapy, and within one week after the therapy had been completed. After the therapy, there were significant differences among the three groups in terms of the nocturnal sleep time (NST) (F(2,117) = 6.84, p < 0.05) and sleep efficiency (SE) (F(2,117) = 7.69, p < 0.05). Significant improvement in the sleep behaviors was observed in the experimental group using magnetic pearls. In a backward multiple regression, the effect of auricular therapy on SE after allowing for age in female participants is of high statistical significance (F(3,106) = 9.04, p < 0.001). The paper concludes that auricular therapy using magnetic pearls is an effective means of improving the quantity and quality of sleep in the elderly.

Differential expression of proteins in kidney, eye, aorta, and serum of diabetic and non-diabetic rats

Diabetes mellitus (DM) is a chronic progressive disease that often results in microvascular and macrovascular complications, yet its pathogenesis is not clear. Automated proteomic technology, coupled with powerful bioinformatics and statistical tools, can provide new insights into the molecular alterations implicated in DM. Following our previous findings of redox changes in the eye and aorta of diabetic rats, as well as the activities of different antioxidant enzymes during the development of DM, this study is further launched to find potential biomarkers by comparing the serum and tissue samples of 26 diabetic rats (8 weeks after streptozotocin [STZ] administration) with 29 normal controls using surface enhanced laser desorption/ionization time‐of‐flight mass spectrometry (SELDI‐TOF MS) technology. Eight potential biomarkers were found in the serum, one potential biomarker was found in the kidney and eye, respectively, whereas three potential biomarkers were discovered in the aorta. One of the serum biomarker candidates was found to match the C‐reactive protein (CRP) in the Swiss‐Prot knowledgebase. Further validation has been conducted by ELISA kit to confirm the role of CRP during the development of DM. To conclude, the increased level of CRP in diabetic serum demonstrated in this study indicates that the development of DM is associated with inflammation. This is also the first report demonstrating that some potential lysate biomarkers in the kidney, eye, and aorta may be involved in the development of diabetes and its complications. Further identification and evaluation of these potential biomarkers will help unravel the underlying mechanisms of the disease. J. Cell. Biochem.

Apoptosis of ovarian cancer cells induced by methylene blue-mediated sonodynamic action

OBJECTIVE The present study aims to investigate apoptosis of ovarian cancer cells induced by methylene blue (MB)-mediated sonodynamic therapy (SDT). METHODS The MB concentration was kept constant at 100μM and ovarian cancer HO-8910 cells were exposed to ultrasound therapy for 5s with an intensity of 0.46W/cm(2). The cytotoxicity was investigated 24h after MB-mediated sonodynamic action. Apoptosis was analyzed using a flow cytometer with Annexin V-FITC and propidium iodine (PI) staining as well as fluorescence microscopy with Hoechst 33258 staining. Intracellular reactive oxygen species (ROS) level was measured by flow cytometer with 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) staining. RESULTS The cytotoxicity of MB-mediated SDT on HO-8910 cells after MB-mediated SDT was significantly higher than those of other treatments including ultrasound alone, MB alone and sham treatment. Flow cytometric analysis showed a significant increase in the early and late apoptotic cell populations by MB-mediated SDT of HO-8910 cells. Nuclear condensation and increased ROS levels were also found in HO-8910 cells treated by MB-mediated SDT. CONCLUSIONS Our findings demonstrated that MB-mediated sonodynamic action significantly induced apoptosis of HO-8910 cells and an increase in intracellular ROS level. This indicates that apoptosis is an important mechanism of cell death induced by MB-mediated SDT. Thus, MB-mediated SDT might be a potential therapeutic strategy for combating ovarian cancer.

HYPOCRELLIN B ENHANCES ULTRASOUND-INDUCED CELL DEATH OF NASOPHARYNGEAL CARCINOMA CELLS

Hypocrellin B, a natural pigment from a traditional Chinese herb, has been attracting extensive attention. The present study aims to investigate whether hypocrellin B can enhance cell death induced by ultrasound sonification on nasopharyngeal carcinoma cells in vitro. The sonodynamic action of hypocrellin B was investigated on nasopharyngeal carcinoma cell line CNE2 cells as tumor model cells. In the experiments, the hypocrellin B concentration was kept constant at 2.5 microM and the cells were subject to ultrasound exposure for 15 s at an intensity of 0.65 W/cm(2). Cytotoxicity was investigated 24 h after ultrasound sonification. Apoptosis was evaluated using flow cytometry with annexin V-FITC and propidium iodine staining and nuclear staining with Hoechst 33258. Cell ultrastructure morphology was observed using transmission electron microscopy (TEM). No significant dark cytotoxicity of hypocrellin B in the CNE2 cells was observed at the concentration of 2.5 microM. The cell death rate induced by ultrasound sonification was significantly higher in the presence of hypocrellin B than in the absence of hypocrellin B. Flow cytometry showed that ultrasound exposure in the presence of hypocrellin B significantly increased the early and late apoptotic rate, 18.64% and 22.57%, respectively, compared with the controls. Nuclear condensation was observed in the nuclear staining and swollen mitochondria and more vacuolar and broken cell membrane were found in TEM after the treatment of hypocrellin B and ultrasound. Our findings demonstrated that the presence of hypocrellin B significantly enhanced the cytotoxicity of ultrasound radiation in CNE2 cells, suggesting that hypocrellin B is a novel sonosensitizer and hypocrellin B-mediated sonodynamic therapy is a potential therapeutic modality in the management of malignant tumors.

The long-term effects of auricular therapy using magnetic pearls on elderly with insomnia.

OBJECTIVE To examine the long-term effect of auricular therapy using magnetic pearls administered for the elderly suffering from insomnia. DESIGN A follow-up study after a randomized controlled trial. SETTINGS Four hostels for the elderly in Hong Kong. INTERVENTIONS This paper focuses on reporting the long-term effect of auricular therapy using magnetic pearls in the experimental group of a randomized controlled study. Fifteen volunteer participants were followed up at 1-, 3-, and 6-month intervals after a 3-week treatment course. OUTCOME MEASURES Objective sleep parameters using actigraphic monitoring were collected at different intervals of time after the therapy. RESULTS Results of RANOVA demonstrate that there was a significant difference of nocturnal sleep time (F(2.30,29.90)=3.63, P<0.05) and marginally differences of sleep efficiency (F(4,52)=2.52, P=0.05) at baseline, immediately after the therapy, and at the three time intervals at 1, 3 and 6 months. The results illustrate that the mean nocturnal sleep time (F=4.95, P=0.30, R(2)=0.91) and the mean sleep efficiency (F=13.50, P=0.19, R(2)=0.96) also remained constant over the 6-month follow up period. The results of least square polynomial regression analysis also illustrate that the mean NST (F=4.95, P=0.30, R(2)=0.91) and the mean sleep efficiency (F=13.50, P=0.19, R(2)=0.96) remained constant over the 6-month follow up period. CONCLUSION The results of this follow up study indicate that auricular therapy using magnetic pearls could have a long-term effect, at least within the observed period of time, on improving the quality as well as the quantity of sleep among the elderly.

Mitochondrial Damage in Nasopharyngeal Carcinoma Cells Induced by Ultrasound Radiation in the Presence of Hypocrellin B

Objective. The mitochondrion is an important target of ultrasound‐induced cell death. This study aimed to investigate the mitochondrial damage in nasopharyngeal carcinoma (NPC) cells induced by ultrasound radiation in the presence of hypocrellin B (HB). Methods. The NPC cell line CNE2 was used to investigate the effect of HB on ultrasonic action with an HB concentration of 2.5 μmol/L and ultrasound exposure for 15 seconds at an intensity of 0.65 W/cm2. Cytotoxicity was investigated 24 hours after ultrasound exposure. Mitochondrial structure changes were observed by transmission electron microscopy. The mitochondrial membrane potential was evaluated by confocal laser‐scanning microscopy with rhodamine 123 staining. Results. The mean death rates of the CNE2 cells ± SD were 25.14% ± 1.50% after ultrasound radiation alone and 76.72% ± 1.13% after ultrasound radiation in the presence of HB. Transmission electron microscopy showed that slightly enlarging mitochondria were found in the ultrasound‐treated cells. After treatment with ultrasound and HB together, some cells had seriously damaged mitochondria, namely, obvious swollen mitochondria and mitochondria in which cristae had almost completely disappeared. The mitochondrial membrane potential was more significantly collapsed when the CNE2 cells were exposed to HB for 5 hours and then ultrasound at 0.65 mW/cm2 than with ultrasound radiation alone (P < .05). Conclusions. Hypocrellin B significantly enhanced the cytotoxicity of ultrasound radiation in the CNE2 cells. The damage to the mitochondrial structure and function might be an important cause of death in the CNE2 cells induced by treatment with ultrasound radiation and HB together.

Hypocrellin B-mediated sonodynamic action induces apoptosis of hepatocellular carcinoma cells

OBJECTIVE The present study aims to investigate apoptosis of hepatocellular carcinoma cells induced by hypocrellin B-mediated sonodynamic action. METHODS The hypocrellin B concentration was kept constant at 2.5 μM and cells from the hepatocellular carcinoma HepG2 cell line were exposed to ultrasound with an intensity of 0.46 W/cm(2) for 8s. Cell cytotoxicity was quantified using an MTT assay 24 h after sonodynamic therapy (SDT) of hypocrellin B. Apoptosis was investigated using a flow cytometry with Annexin V-FITC and propidium iodine staining. Intracellular reactive oxygen species (ROS) levels were detected using a flow cytometry with 2,7-dichlorodihydrofluorecein diacetate (DCFH-DA) staining. RESULTS The cytotoxicity of hypocrellin B-mediated sonodynamic action on HepG2 cells was significantly higher than those of other treatments including ultrasound alone, hypocrellin B alone and sham treatment. Flow cytometry showed that hypocrellin B-induced sonodynamic action markedly enhanced the apoptotic rate of HepG2 cells. Increased ROS was observed in HepG2 cells after being treated with hypocrellin B-mediated sonodynamic action. CONCLUSIONS Our data demonstrated that hypocrellin B-mediated sonodynamic action remarkably induced apoptosis of HepG2 cells, suggesting that apoptosis is an important mechanism of cell death induced by hypocrellin B-mediated SDT.