Stability of Multi-Wall Carbon Nanotube and Graphite in Acids

Energy Conversion & StorageMulti-walled carbon nanotubes (MWCNT) were treated in five commonly used acidic media with different pKa values. The stability of the MWCNT was evaluated by using various characterization techniques. The results indicated that oxidative damage of MWCNT was not closely related to acid strength, and that the MWCNT was more sensitive to the oxidizing nature of the acid. The oxidation of highly oriented pyrolytic graphite (HOPG) by chemical oxidants in air has been investigated. The oxidation of HOPG top surface was carried out by treating with H2SO4/HNO3 mixture. The samples for oxidation were prepared by molding in polyethylene. To evaluate the effects of oxidants on surface of graphite various techniques have been applied to study the damage on surface of HOPG. As a result, the MWCNT treated with the strongest acid, trifluoromethanesulfonic acid (pKa = -15.9), only reached oxygen content of 1.8%, while nitric acid (pKa = -1.5)/sulfuric acid (pKa = -3.0) treated MWCNT showed oxygen content as high as 19% after 24 h treatment. The remaining acidic media did not noticeably increase the oxygen content of the MWCNT up to 24 h treatment. The oxidized HOPG surface reached its oxygen content of 20.9% after 4 days of treatment. The results are supported by gradual increase of the intensity of D-band in Raman spectra with respect to time.ope

Strain-induced delamination of edge-grafted graphite

Edge-selectively grafted graphite (EGG) with poly(ether-ketone) was prepared by the Friedel-Crafts acylation in a mild polyphosphoric acid (PPA)-phosphorous pentoxide (P2O5) mixture. The homogeneous reaction dope was coagulated in air moisture at different temperatures. The morphology of expanded EGG was changed from balls, balls/rods and rods with respect to coagulation temperatures of 80, 60, 40 and 25 degrees C, respectively.close1

Visfatin exerts angiogenic effects on human umbilical vein endothelial cells through the mTOR signaling pathway

AbstractThe biologically active factors known as adipocytokines are secreted primarily by adipose tissues and can act as modulators of angiogenesis. Visfatin, an adipocytokine that has recently been reported to have angiogenic properties, is upregulated in diabetes, cancer, and inflammatory diseases. Because maintenance of an angiogenic balance is critically important in the management of these diseases, understanding the molecular mechanism by which visfatin promotes angiogenesis is very important. In this report, we describe our findings demonstrating that visfatin stimulates the mammalian target of the rapamycin (mTOR) pathway, which plays important roles in angiogenesis. Visfatin induced the expression of hypoxia-inducible factor 1α (HIF1α) and vascular endothelial growth factor (VEGF) in human endothelial cells. Inhibition of the mTOR pathway by rapamycin eliminated the angiogenic and proliferative effects of visfatin. The visfatin-induced increase in VEGF expression was also eliminated by RNA interference-mediated knockdown of the 70-kDa ribosomal protein S6 kinase (p70S6K), a downstream target of mTOR. Visfatin inactivated glycogen synthase kinase 3β (GSK3β) by phosphorylating it at Ser-9, leading to the nuclear translocation of β-catenin. Both rapamycin co-treatment and p70S6K knockdown inhibited visfatin-induced GSK3β phosphorylation at Ser-9 and nuclear translocation of β-catenin. Taken together, these results indicate that mTOR signaling is involved in visfatin-induced angiogenesis, and that this signaling leads to visfatin-induced VEGF expression and nuclear translocation of β-catenin

Clinical outcomes of pneumococcal pneumonia caused by antibiotic-resistant strains in Asian countries: a study by the Asian network for surveillance of resistant pathogens

To evaluate the clinical outcomes of pneumococcal pneumonia caused by antibiotic-resistant strains in Asian countries, we performed a prospective observational study of 233 cases of adult pneumococcal pneumonia in 9 Asian countries from January 2000 to June 2001. Among 233 isolates, 128 (55%) were not susceptible to penicillin (25.3% were intermediately susceptible, and 29.6% were resistant). Clinical severity of pneumococcal pneumonia was not significantly different between antibiotic-resistant and antibiotic-susceptible groups. Mortality rates among patients with pneumococcal pneumonia caused by penicillin-, cephalosporin-, or macrolide-resistant strains were not higher than those with antibiotic-susceptible pneumococcal pneumonia. Bacteremia and mechanical ventilation were significant risk factors for death, but any kind of antibiotic resistance was not associated with increased mortality due to pneumococcal pneumonia. Outcome of pneumococcal pneumonia was not significantly affected by drug resistance, and current antimicrobial regimens are mostly effective in the treatment of pneumococcal pneumonia, despite the widespread emergence of in vitro resistance

A Novel DHCR7 Mutation in a Smith-Lemli-Opitz Syndrome Infant Presenting with Neonatal Cholestasis

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive malformation syndrome caused by a defect in cholesterol biosynthesis. The incidence is very low in Asians and only one case has been reported in Korea thus far. Recently, we found an infant with neonatal cholestasis. He had microcephaly, ambiguous genitalia, cleft palate, syndactyly of toes, patent ductus arteriosus and hypertrophic pyloric stenosis. The serum cholesterol was decreased and serum 7-dehydrocholesterol was markedly elevated. Genetic analysis of the DHCR7 gene identified a novel missense mutation (Pro227Ser) as well as a known mutation (Gly303Arg) previously identified in a Japanese patient with SLOS. Although rare in Korea, SLOS should be considered in the differential diagnosis of neonatal cholestasis, especially in patients with multiple congenital anomalies and low serum cholesterol levels.Chae JH, 2007, J CHILD NEUROL, V22, P1297, DOI 10.1177/0883073807307099Yu H, 2005, CLIN GENET, V68, P383, DOI 10.1111/j.1399-0004.2005.00515.xMatsumoto Y, 2005, J HUM GENET, V50, P353, DOI 10.1007/s10038-005-0267-3Rossi M, 2005, AM J MED GENET A, V132A, P144, DOI 10.1002/ajmg.a.30426WITSCHBAUMGARTN.M, 2005, HUM MUTAT, V25, P412Herman GE, 2003, HUM MOL GENET, V12, pR75, DOI 10.1093/hmg/ddg072Yu HW, 2000, HUM MOL GENET, V9, P1385Kelley RI, 2000, J MED GENET, V37, P321Witsch-Baumgartner M, 2000, AM J HUM GENET, V66, P402Waterham HR, 1998, AM J HUM GENET, V63, P329Kelley RI, 1998, AM J HUM GENET, V63, P322Fitzky BU, 1998, P NATL ACAD SCI USA, V95, P8181Wassif CA, 1998, AM J HUM GENET, V63, P55Ryan AK, 1998, J MED GENET, V35, P558Moebius FF, 1998, P NATL ACAD SCI USA, V95, P1899Tsukahara M, 1998, AM J MED GENET, V75, P118Cunniff C, 1997, AM J MED GENET, V68, P263Kelley RI, 1997, AM J MED GENET, V68, P251OPITZ JM, 1994, AM J MED GENET, V50, P344TINT GS, 1994, NEW ENGL J MED, V330, P107

c-MET-positive circulating tumor cells and cell-free DNA as independent prognostic factors in hormone receptor-positive/HER2-negative metastatic breast cancer

Background Endocrine therapy resistance in hormone receptor-positive/HER2-negative (HR+/HER2−) breast cancer (BC) is a significant clinical challenge that poses several unmet needs in the management of the disease. This study aimed to investigate the prognostic value of c-MET-positive circulating tumor cells (cMET+ CTCs), ESR1/PIK3CA mutations, and cell-free DNA (cfDNA) concentrations in patients with hormone receptor-positive (HR+) metastatic breast cancer (mBC). Methods Ninety-seven patients with HR+ mBC were prospectively enrolled during standard treatment at Samsung Medical Center. CTCs were isolated from blood using GenoCTC® and EpCAM or c-MET CTC isolation kits. PIK3CA and ESR1 hotspot mutations were analyzed using droplet digital PCR. CfDNA concentrations were calculated using internal control copies from the ESR1 mutation test. Immunocytochemistry was performed to compare c-MET overexpression between primary and metastatic sites. Results The proportion of c-MET overexpression was significantly higher in metastatic sites than in primary sites (p = 0.00002). Survival analysis showed that c-MET+ CTC, cfDNA concentration, and ESR1 mutations were significantly associated with poor prognosis (p = 0.0026, 0.0021, and 0.0064, respectively) in HR+/HER2− mBC. By contrast, EpCAM-positive CTC (EpCAM+ CTC) and PIK3CA mutations were not associated with progression-free survival (PFS) in HR+/HER2− mBC. Multivariate analyses revealed that c-MET+ CTCs and cfDNA concentration were independent predictors of PFS in HR+/HER2− mBC. Conclusions Monitoring c-MET+ CTC, rather than assessing c-MET expression in the primary BC site, could provide valuable information for predicting disease progression, as c-MET expression can change during treatment. The c-MET+ CTC count and cfDNA concentration could provide complementary information on disease progression in HR+ /HER2− mBC, highlighting the importance of integrated liquid biopsy.This research was supported by Grants from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI) funded by the Ministry of Health & Welfare (HI19C0141; to ES Chang, M Sung, JY Song, K Jung, and YL Choi), Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2022R1A6A1A03046247; to YK Shin), NRF Grant funded by the Ministry of Science and ICT (2022R1A2C2006322; to ES Chang, M Sung, JY Song, K Jung, and YL Choi), and Future Medicine 20*30 Project of the Samsung Medical Center (#SMO1230021; to YL Choi), Republic of Kore

Bloodstream Infections and Clinical Significance of Healthcare-associated Bacteremia: A Multicenter Surveillance Study in Korean Hospitals

Recent changes in healthcare systems have changed the epidemiologic paradigms in many infectious fields including bloodstream infection (BSI). We compared clinical characteristics of community-acquired (CA), hospital-acquired (HA), and healthcare-associated (HCA) BSI. We performed a prospective nationwide multicenter surveillance study from 9 university hospitals in Korea. Total 1,605 blood isolates were collected from 2006 to 2007, and 1,144 isolates were considered true pathogens. HA-BSI accounted for 48.8%, CA-BSI for 33.2%, and HCA-BSI for 18.0%. HA-BSI and HCA-BSI were more likely to have severe comorbidities. Escherichia coli was the most common isolate in CA-BSI (47.1%) and HCA-BSI (27.2%). In contrast, Staphylococcus aureus (15.2%), coagulase-negative Staphylococcus (15.1%) were the common isolates in HA-BSI. The rate of appropriate empiric antimicrobial therapy was the highest in CA-BSI (89.0%) followed by HCA-BSI (76.4%), and HA-BSI (75.0%). The 30-day mortality rate was the highest in HA-BSI (23.0%) followed by HCA-BSI (18.4%), and CA-BSI (10.2%). High Pitt score and inappropriate empirical antibiotic therapy were the independent risk factors for mortality by multivariate analysis. In conclusion, the present data suggest that clinical features, outcome, and microbiologic features of causative pathogens vary by origin of BSI. Especially, HCA-BSI shows unique clinical characteristics, which should be considered a distinct category for more appropriate antibiotic treatment