Antitumor activity studies of iridium (III) polypyridine complexes-loaded liposomes against gastric tumor cell in vitro.

Two iridium (III) polypyridine complexes [Ir(ppy)2(BIP)]PF6 (ppy = 2-phenylpyridine, BIP = 2-biphenyl-1H-imidazo[4,5-f][1,10]phenanthroline, Ir1), [Ir(piq)2(BIP)]PF6 (piq = 1-phenylisoquinoline, Ir2) and their liposomes Ir1lipo and Ir2lipo were synthesized and characterized. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cytotoxic activity against several cancer cells (A549, HepG2, SGC-7901, Bel-7402, HeLa) and non-cancer cell (mouse embryonic fibroblast, NIH3T3). The results showed that Ir1lipo displays the high cytotoxicity toward SGC-7901 with IC50 value of 5.8 ± 0.2 µM, while the complexes have no cytotoxicity toward A549, HepG2, Bel-7402 and HeLa cells. The cell colony demonstrated that the iridium (III) complexes-loaded liposomes can inhibit cell proliferation, induce cell cycle arrest at G0/G1 phase. Moreover, they also cause autophagy, induce a decrease of mitochondrial membrane potential and increase intracellular reactive oxygen species (ROS) content. These results suggest that the complexes encapsulated liposomes Ir1lipo and Ir2lipo inhibit the growth of SGC-7901 cells through a ROS-mediated mitochondrial dysfunction and activating the PI3K (phosphoinositide-3 kinase)/ AKT (protein kinase B) signaling pathways.

Why did outbreaks of severe acute respiratory syndrome occur in some hospital wards but not in others?

BACKGROUND: Most documented "superspreading events" of severe acute respiratory syndrome (SARS) occurred in hospitals, but the underlying causes remain unclear. We systematically analyzed the risk factors for nosocomial outbreaks of SARS among hospital wards in Guangzhou and Hong Kong, China. METHODS: A case-control study was conducted. Case wards were hospital wards in which superspreading events of SARS occurred, and control wards were wards in which patients with SARS were admitted, but no subsequent nosocomial outbreaks occurred. Information on environmental and administrative factors was obtained through visits to the wards and interviews with ward managers or nursing officers. Relevant information about host factors was abstracted from the medical records. Logistic regression analyses were used to identify the major risk factors for superspreading events. RESULTS: Eighty-six wards in 21 hospitals in Guangzhou and 38 wards in 5 hospitals in Hong Kong were included in the study. Six risk factors were significant in the final multiple-logistic regression model: minimum distance between beds of < or = 1 m (odds ratio [OR], 6.94; 95% confidence interval [CI], 1.68-28.75), availability of washing or changing facilities for staff (OR, 0.12; 95% CI, 0.02-0.97), whether resuscitation was ever performed in the ward (OR, 3.81; 95% CI, 1.04-13.87), whether staff members worked while experiencing symptoms (OR, 10.55; 95% CI, 2.28-48.87), whether any host patients (index patient or the first patient with SARS admitted to a ward) required oxygen therapy (OR, 4.30; 95% CI, 1.00-18.43), and whether any host patients required bi-level positive airway pressure ventilation (OR, 11.82; 95% CI, 1.97-70.80). CONCLUSIONS: Our results revealed that factors that were associated with the ward environment and administration were important in nosocomial outbreaks of SARS. The lessons learned from this study remain very important and highly relevant to the daily operation of hospital wards if we are to prevent nosocomial outbreaks of other respiratory infections in the future.

[A study of the architectural factors and the infection rates of healthcare workers in isolation units for severe acute respiratory syndrome].

OBJECTIVE: To investigate measures to prevent the outbreak of severe acute respiratory syndrome (SARS) in healthcare workers in isolation units. METHODS: The architectural factors and the infection of healthcare workers in different wards in our hospital between 30 January 2003 and 30 March 2003 were analyzed. RESULTS: Four kinds of isolation wards were evaluated, including the ward where the thirty-first bed lied in on the twelfth floor, the laminar flow ward in the intensive care unit (ICU) where the tenth bed lied in on the fifteenth floor, the ward where the twenty-seventh bed lied in on the thirteenth floor of Building A, and thirty wards on the fourteenth to eighteenth floors of Building B. The ratios (m2/m3) of the area of the ventilation windows to the volume of the room were 0, 0, 1:95 and 1:40, respectively. Numbers of SARS cases in the wards mentioned above were 1, 1, 1 and 96, respectively. The total lengths (hour) of hospitalization were 43, 168, 110 and 1,272, respectively. The infection rates of the healthcare workers in the areas mentioned above were 73%, 32%, 28% and 2%, respectively. The difference of the infection rates was of statistical significance. CONCLUSION: In addition to strict personal protective measures, isolation of SARS cases in wards with high ratio of the area of ventilation windows to the volume of the room and good ventilation may be the key to preventing the outbreak of SARS in healthcare workers in isolation units.