Several extraction, separation, and detection methods of polycyclic
aromatic hydrocarbons (PAHs)
in meat products were evaluated by using liquid chromatography.
Results showed that Soxhlet
extraction of PAHs followed by purification with a Sep-Pak Florisil
cartridge removed more impurities
than the sonication method. With HPLC, a mobile phase of
acetonitrile−water (55:45, v:v) was
maintained for 2 min, linearly programmed to 100% acetonitrile over a
23 min period, and maintained
for 15 min. Sixteen PAHs were separated by a C18
column and detected by UV at 254 nm, while 15
PAHs were detected with fluorescence. The latter method was found
to have 20−320 times higher
sensitivity than the former. The following settings (excitation
wavelength/emission wavelength)
were used for fluorescence: λ1 = 270 nm/340 nm
(naphthalene, acenaphthene, fluorene); λ2 =
254
nm/375 nm (phenanthrene); λ3 = 260 nm/420 nm
(anthracene, fluoranthene); λ4 = 254 nm/390
nm
(pyrene, benzo[a]anthracene, chrysene),
λ5 = 260 nm/420 nm
(benzo[b]fluoranthene,
benzo[k]fluoranthene, benzo[a]pyrene,
dibenz[a,h]anthracene,
benzo[g,h,i]perylene);
λ6 = 293 nm/498 nm
(indeno[1,2,3-c,d]pyrene). The
presence of PAHs in some commercial meat products was also
determined.
Keywords: Polycyclic aromatic hydrocarbon; meat products; liquid
chromatography
Protein phosphatase 2A (PP2A) is a tumor suppressor, which is functionally defective in various cancers. Previously, we found that PP2A activity determined the anticancer effect of bortezomib and erlotinib in hepatocellular carcinoma (HCC) cells. Here, we tested a novel erlotinib derivative, TD52, in four HCC cell lines, PLC5, Huh-7, Hep3B and Sk-Hep1. Using MTT and flow cytometry, we showed that TD52 had more potent apoptotic effects than erlotinib in HCC cells. TD52-induced apoptosis was associated with dose- and time- dependent reactivation of PP2A and downregulation of cancerous inhibitor of protein phosphatase 2A (CIP2A) and p-Akt. Inhibition of PP2A or ectopic expression of CIP2A or Akt in PLC5 cells abolished the effects of TD52. Furthermore, we demonstrated that TD52 affected the binding of Elk-1 to the proximal promoter of the CIP2A gene, thus downregulating transcription of CIP2A. Importantly, TD52-induced tumor inhibition was associated with reactivation of PP2A and downregulation of CIP2A and p-Akt in vivo. In conclusion, we found that enhancement of PP2A activity by inhibition of CIP2A determines the apoptotic effect induced by TD52. Our findings disclose the therapeutic mechanism of this novel targeted agent, and suggest the therapeutic potential and feasibility of developing PP2A enhancers as a novel anticancer strategy.
This study investigated the correlation between antibiotic consumption and resistance among Staphylococcus aureus and enterococci causing healthcare-associated infections at a university hospital in Taiwan from 2000 to 2009. Overall, the trend of total consumption (defined daily dose [DDD] per 1,000 patient-days) of glycopeptides, including vancomycin and teicoplanin, significantly increased during 2000 to 2003 and remained stable during 2004-2009. Vancomycin consumption significantly increased during 2003 and decreased after 2004. A significant decrease in the resistance rate with time was found for oxacillin- and gentamicin-resistant S. aureus. In contrast, the rates of vancomycin- and teicoplanin-resistant enterocci increased significantly. A significant correlation was found between the increased use of extended-spectrum cephalosporins, β-lactam-β-lactamase inhibitor combinations, carbapenems and the decreased prevalence of methicillin-resistant S. aureus (MRSA). In contrast, the increased use of teicoplanin, extended-spectrum cephalosporins, β-lactam-β-lactamase inhibitor combinations, and carbapenems was correlated with the increased prevalence of vancomycin-resistant enterococci (VRE). In conclusion, this 10-year study in a single institution identified different correlations between the prescription of antibiotics and the resistance rates of MRSA and VRE. Strict implementation of infection control policy based on these correlates would be helpful in decreasing the presence of these multidrug-resistant pathogens in hospitals.
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