Elevated BCRP/ABCG2 Expression Confers Acquired Resistance to Gefitinib in Wild-Type EGFR-Expressing Cells

The sensitivity of non-small cell lung cancer (NSCLC) patients to EGFR tyrosine kinase inhibitors (TKIs) is strongly associated with activating EGFR mutations. Although not as sensitive as patients harboring these mutations, some patients with wild-type EGFR (wtEGFR) remain responsive to EGFR TKIs, suggesting that the existence of unexplored mechanisms renders most of wtEGFR-expressing cancer cells insensitive.Here, we show that acquired resistance of wtEGFR-expressing cancer cells to an EGFR TKI, gefitinib, is associated with elevated expression of breast cancer resistance protein (BCRP/ABCG2), which in turn leads to gefitinib efflux from cells. In addition, BCRP/ABCG2 expression correlates with poor response to gefitinib in both cancer cell lines and lung cancer patients with wtEGFR. Co-treatment with BCRP/ABCG2 inhibitors enhanced the anti-tumor activity of gefitinib.Thus, BCRP/ABCG2 expression may be a predictor for poor efficacy of gefitinib treatment, and targeting BCRP/ABCG2 may broaden the use of gefitinib in patients with wtEGFR

A Post-hoc Study of D-Amino Acid Oxidase in Blood as an Indicator of Post-stroke Dementia

Stroke is an important risk factor for dementia. Epidemiological studies have indicated a high incidence of dementia in stroke patients. There is currently no effective biomarker for the diagnosis of post-stroke dementia (PSD). D-amino acid oxidase (DAO) is a flavin-dependent enzyme widely distributed in the central nervous system. DAO oxidizes D-amino acids, a process which generates neurotoxic hydrogen peroxide and leads to neurodegeneration. This study aimed to examine post-stroke plasma DAO levels as a biomarker for PSD. In total, 53 patients with PSD, 20 post-stroke patients without dementia (PSNoD), and 71 age- and gender-matched normal controls were recruited. Cognitive function was evaluated at more than 30 days post-stroke. Plasma DAO was measured using the enzyme-linked immunosorbent assay. White matter hyperintensity (WMH), a neuroimaging biomarker of cerebral small vessel diseases, was determined by magnetic resonance imaging. We found that plasma DAO levels were independently higher in PSD subjects than in PSNoD subjects or the controls and were correlated with the WMH load in stroke patients. Using an area under the curve (AUC)/receiver operating characteristic analysis, plasma DAO levels were significantly reliable for the diagnosis of PSD. The sensitivity and specificity of the optimal cut-off value of 321 ng/ml of plasma DAO for the diagnosis of PSD were 75 and 88.7%, respectively. In conclusion, our data support that plasma DAO levels were increased in PSD patients and correlated with brain WMH, independent of age, gender, hypertension, and renal function. Plasma DAO levels may therefore aid in PSD diagnosis

Incidence Rate and Predictors of Globus Pallidus Necrosis after Charcoal Burning Suicide

Objective: This study examined predictors of globus pallidus necrosis as there was a paucity of literature of globus pallidus necrosis resulted from carbon monoxide poisoning after charcoal burning suicide. Methods: A total of 67 patients who had attempted charcoal burning suicide were recruited and stratified into two subgroups based on either presence (n = 40) or absence (n = 27) of globus pallidus necrosis. Demographic, clinical, laboratory, and radiographic data were obtained for cross-sectional analysis. All patients were followed to investigate the risks for mortality. Results: The patients aged 36.8 ± 11.1 years (67.2%) were male. Patients with globus pallidus necrosis were younger (p = 0.044) and had less hypertension (p = 0.015) than patients without globus pallidus necrosis. Furthermore, patients with globus pallidus necrosis suffered from severer medical complications, i.e., fever (p = 0.008), acute myocardial injury (p = 0.022), acute rhabdomyolysis (p = 0.022), and neuropsychiatric symptoms (p < 0.001) than patients without globus pallidus necrosis. Moreover, patients with globus pallidus necrosis received less hyperbaric oxygen therapy than without necrosis (p = 0.024). Two patients (3.0%) died on arrival. In a multivariable regression model, it was revealed that acute myocardial injury (odds ratio 4.6, confidence interval 1.1-18.9, p = 0.034) and neuropsychiatric symptoms (odds ratio 8.0, confidence interval 2.0-31.4, p = 0.003), decreased blood bicarbonate level (odds ratio 0.8, confidence interval 0.7-1.0, p = 0.032), and younger age (odds ratio 0.9, confidence interval 0.9-1.0, p = 0.038) were significant predictors for globus pallidus necrosis. Conclusion: Although patients who had attempted charcoal burning suicide had a low mortality rate (3.0%), globus pallidus necrosis was not uncommon (59.7%) in this population. Further studies are warranted.Chang Gung Memorial Hospital, Linkou, TaiwanChang Gung Memorial Hospital [CLRPG3D0016, CORPG5G0051]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

S-adenosyl-L-methionine:farnesoic acid O-methyltransferase of Passalus cornutus: purification and characterization

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.In Coleoptera, the final steps in juvenile hormone (JH) biosynthesis are believed to be methylation of farnesoic acid (FA) followed by epoxidation. Source of the methyl group is S-adenosyl-L-methionine, and the reaction is catalyzed by S-adenosyl-L-methionine:farnesoic acid 0-methyltransferase (FAMT). This enzyme was purified to homogeneity from a cytosolic preparation of Passalus cornutus corpora allata. The molecular weight of the purified enzyme was determined to be 28,100 by SDS-polyacrylamide gel electrophoresis. Three isoforms (pI 5.2, 4.8, 4.6) of FAMT were observed by chromatofocusing. The purified enzyme was photoaffinity labeled with S-[methyl3H]adenosyl-L-methionine. only a single polypeptide band with an electrophoretic mobility identical to that of FAMT was radiolabeled. Enzyme kinetics studies revealed that the Km for S-adenosyl-L-methionine is 5.3 x 104 M and that the Km for FA is 2.1 X .10-7 M. The substrate specificity of FAMT was tested with a competition enzyme assay. Purified FAMT was assayed in the presence of equimolar amounts of FA, JH-I acid, JH-II acid, and JHIII acid, with S-[methyl-3H]adenosyl-L-methionine as the radiolabeled substrate. The resulting methyl esters were analyzed by HPLC. The ratio of products (methyl farnesoate : JH-I : JH-II : JH-III = I : 0.14 : 0.05 : 0.02) shows that the enzyme has highest affinity for FA and suggests that FA is indeed its natural substrate. The result also supports the presumed sequence for JH biosynthesis (methylation followed by epoxidation) in CA of Coleoptera

S-adenosyl-L-methionine:farnesoic acid O-methyltransferase of Passalus cornutus: purification and characterization

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.In Coleoptera, the final steps in juvenile hormone (JH) biosynthesis are believed to be methylation of farnesoic acid (FA) followed by epoxidation. Source of the methyl group is S-adenosyl-L-methionine, and the reaction is catalyzed by S-adenosyl-L-methionine:farnesoic acid 0-methyltransferase (FAMT). This enzyme was purified to homogeneity from a cytosolic preparation of Passalus cornutus corpora allata. The molecular weight of the purified enzyme was determined to be 28,100 by SDS-polyacrylamide gel electrophoresis. Three isoforms (pI 5.2, 4.8, 4.6) of FAMT were observed by chromatofocusing. The purified enzyme was photoaffinity labeled with S-[methyl3H]adenosyl-L-methionine. only a single polypeptide band with an electrophoretic mobility identical to that of FAMT was radiolabeled. Enzyme kinetics studies revealed that the Km for S-adenosyl-L-methionine is 5.3 x 104 M and that the Km for FA is 2.1 X .10-7 M. The substrate specificity of FAMT was tested with a competition enzyme assay. Purified FAMT was assayed in the presence of equimolar amounts of FA, JH-I acid, JH-II acid, and JHIII acid, with S-[methyl-3H]adenosyl-L-methionine as the radiolabeled substrate. The resulting methyl esters were analyzed by HPLC. The ratio of products (methyl farnesoate : JH-I : JH-II : JH-III = I : 0.14 : 0.05 : 0.02) shows that the enzyme has highest affinity for FA and suggests that FA is indeed its natural substrate. The result also supports the presumed sequence for JH biosynthesis (methylation followed by epoxidation) in CA of Coleoptera

Structural Reorganization of Imidazolium Ionic Liquids Induced by Pressure-Enhanced Ionic Liquid—Polyethylene Oxide Interactions

Mixtures of polyethylene oxide (PEO, M.W.~900,000) and imidazolium ionic liquids (ILs) are studied using high-pressure Fourier-transform infrared spectroscopy. At ambient pressure, the spectral features in the C–H stretching region reveal that PEO can disturb the local structures of the imidazolium rings of [BMIM]+ and [HMIM]+. The pressure-induced phase transition of pure 1-butyl-3-methylimidazolium bromide ([BMIM]Br) is observed at a pressure of 0.4 GPa. Pressure-enhanced [BMIM]Br-PEO interactions may assist PEO in dividing [BMIM]Br clusters to hinder the aggregation of [BMIM]Br under high pressures. The C–H absorptions of pure 1-hexyl-3-methylimidazolium bromide [HMIM]Br do not show band narrowing under high pressures, as observed for pure [BMIM]Br. The band narrowing of C–H peaks is observed at 1.5 GPa for the [HMIM]Br-PEO mixture containing 80 wt% of [HMIM]Br. The presence of PEO may reorganize [HMIM]Br clusters into a semi-crystalline network under high pressures. The differences in aggregation states for ambient-pressure phase and high-pressure phase may suggest the potential of [HMIM]Br-PEO (M.W.~900,000) for serving as optical or electronic switches