Multi walled carbon nanotube nanocomposites with biodegradable poly(butylene succinate) and their physical characteristics

In order to examine the influence of multi walled carbon nanotube (MWNT) on physical properties of its biodegradable polymer nanocomposite, biodegradable poly(buthylene succinate) (PBS), which was synthesized from diols and dicarboxylic acids, and MWNT nanocomposites were prepared via a melt-mixing method using a co-rotating intermeshing twin screw extruder. Microstructure of the PBS/MWNT nanocomposites and MWNT were investigated via both scanning electron microscopy and transmission electron microscopy. Their rheological properties were also characterized via rotation and oscillation tests using a rotational rheometer with parallel-plate geometry. It was found that shear viscosity, storage modulus and loss modulus of the nanocomposites examined by a rotational rheometer increased with the MWNT content. Especially their sharp increase for MWNT content of ca. 2.0 wt% was observed, indicating its percolation threshold from the rheological viewpoint which was higher than its electrical percolation threshold (1.0 wt%).

Preparation and characteristics of electrospun multiwalled carbon nanotube/polyvinylpyrrolidone nanocomposite nanofiber

Electrospun nanofibers along with multiwalled carbon nanotube (MWNT) become an important issue due to their various engineering applications. Carboxylic acid functionalized multiwalled carbon nanotube (c-MWNT) was successfully embedded into polyvinylpyrrolidone (PVP) matrix, forming polymer nanocomposite nanofibers from an electrospinning process in this study using a custom-made electrospinning apparatus. Initially, the c-MWNT was dispersed well in ethanol using an ultrasonicator. For the electrospinning process of the nanocomposite, c-MWNT dispersion in ethanol and PVP solution were mixed. Surface morphology of the produced c-MWNT/PVP nanofibers was compared with that of pure PVP nanofibers using scanning electron microscopy. The formation and distribution of the c-MWNTs in the nanofibers were also studied by transmission electron microscopy. Alignment of the nanotube in the nanofibers was found to depend on the state of initial dispersion. In addition, it was also found that well-dispersed nanotubes were embedded in the polymer matrix with the alignment along the fiber axis due to the carboxylic acid functionalized MWNT for its good compatibility with the PVP, while the aggregated nanotubes were incorporated as dense entanglement. Raman spectroscopy test was further adopted to characterize the nanofibers.

An Uncommon Arteriovenous Fistula Resulting from Haemodialysis Catheterization despite Applying Ultrasound Guidance: Malposition of Catheter into Right Subclavian Artery

Ultrasound-guided central venous catheterization could reduce the complication rate and increase first time success rate. However, without substantial experience and caution, it could lead to serious complications. We presented a rare case of malposition of the temporary haemodialysis catheter into the right subclavian artery with arteriovenous fistula after real-time 2D ultrasound-guided catheterization into right internal jugular vein. After the occurrence of this complication, we learned that emergency physicians should confirm the position of end portion of the catheter within the target vessel's lumen even when the catheterization was done with real-time 2D ultrasound guidance.

Risk factors for device-associated infection related to organisational characteristics of intensive care units: findings from the Korean Nosocomial Infections Surveillance System

Device-associated infections (DAIs) have been the major causes of morbidity and mortality of patients in intensive care units (ICUs). This study evaluated the risk factors for DAIs in ICUs. Ninety-six medical or surgical ICUs of 56 hospitals participated in the Korean Nosocomial Infections Surveillance System between July 2007 and June 2008. The occurrence of catheter-associated urinary tract infection (CAUTI), central line-associated bloodstream infection (CABSI), and ventilator-associated pneumonia (VAP) were monitored and DAI rates were calculated. Data associated with ICU characteristics were collected and Poisson regression was used for statistical analysis. Rates of CAUTI, CABSI, and VAP were 3.87 per 1000 urinary catheter days, 2.23 per 1000 central line days, and 1.89 per 1000 mechanical ventilator days, respectively. Rates of CAUTI were higher in ICUs in Seoul (P=0.032) and ICUs of major teaching hospitals (P=0.010). The ICUs of university-affiliated hospitals showed lower CAUTI rates (P=0.013). CABSI rates were higher in Seoul (P=0.001) and in medical ICUs (P=0.026). VAP rates were lower in ICUs of hospitals with more than 900 beds compared with hospitals with 400-699 beds (P=0.026). VAP rates were higher in surgical ICUs (P<0.0001) and increased 1.13-fold with each 100-unit increase in beds per infection control professional (P=0.003). The organisational and institutional characteristics of ICUs may influence DAI rates and there is a need for improvement in the incidence of VAP, CAUTI or CABSI.

Inhibitory effects of orobol 7-O-D-glucoside from banaba (Lagerstroemia speciosa L.) on human rhinoviruses replication

AIMS

The anti-human rhinovirus (HRV) activity of orobol 7-O-d-glucoside (O7G) from Lagerstroemia speciosa L. (Lythraceae) was evaluated in Hela cells.

METHODS AND RESULTS

We tested anti-HRV activity of O7G using a cytopathic effect (CPE) reduction method, which exhibited broad-spectrum anti-HRVs activity with a 50% inhibitory concentration (IC(50)) ranging from 0.58 to 8.80 microg ml(-1). The 50% cytotoxicity concentration (CC(50)) of O7G is more than 100 microg ml(-1), and the derived therapeutic indices are more than 12. Ribavirin didn't possess antiviral activity against HRV15, HRV3 and HRV5, but exhibited weak antiviral activity against HRV2 and HRV3, and showed strong anti-HRV6 and -14 activities.

CONCLUSIONS

These results suggest that O7G is a novel drug class with broad spectrum antiviral activity against HRV species A (HRV1B, HRV2, HRV15 and HRV40) and species B (HRV3, HRV6 and HRV14), as well as pleconaril-resistant virus (HRV5).

SIGNIFICANCE AND IMPACT OF THE STUDY

Therefore, these findings provide important information for the utilization of Q7G promising broad spectrum for human rhinovirus treatment.

Genetic analysis of norovirus GII.4 variants circulating in Korea in 2008

Noroviruses are the enteric pathogens most commonly responsible for infectious gastroenteritis and outbreaks of foodborne illness. The GII.4 norovirus, in particular, is responsible for the majority of epidemics. Here, we present data on the distribution of norovirus genotypes in Chungnam, Korea, in 2008, measure genetic variation among GII.4 strains, and compare Korean GII.4 variants with reference strains based on the 237-bp junction of ORF1 and ORF2. We detected 139 different strains, which formed two distinct genetic clusters with significant sequence diversity. One Korean cluster (2008-Korea_a) showed high similarity to the Sakai cluster that appeared in Japan and Europe in 2006. The other cluster (2008-Korea_b) was unique and unrelated to previously reported clusters. Genotype GII.4 was confirmed as the predominant cause of norovirus epidemics in Korea. Foodborne norovirus infections, on the other hand, were generally caused by emerging GII.4 genetic variants similar to those responsible for global epidemics.

Endoscopic treatment of difficult bile duct stones by using a double-lumen basket for laser lithotripsy--a case series

Laser lithotripsy is an effective and safe method for difficult common bile duct (CBD) stones. However, radiolucent laser fibers make accurate fragmentation difficult and require continuous visual control or an accessory for effective targeting. The newly developed double-lumen basket may promote effective laser lithotripsy after stone capture. We performed laser lithotripsy using a double-lumen basket in 14 patients with CBD stones refractive to conventional endoscopic treatment, and evaluated the feasibility and efficacy of this procedure. Stones were successfully fragmented in 13 of 14 patients, and 13 patients eventually became stone-free. Mechanical lithotripsy was applied in two patients with biliary strictures. Minor complications were noted in three patients, including transient hemobilia in one patient. For a selected group of patients with difficult CBD stones, laser lithotripsy using a double-lumen basket appears to be an effective and safe method. However, continuous development of basket protocols to increase the success rate of lithotripsy is needed.

Effects of antioxidant supplements on cancer prevention: meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis aimed to investigate the effect of antioxidant supplements on the primary and secondary prevention of cancer as reported by randomized controlled trials.

METHODS

We searched Medline (PubMed), Excerpta Medica database, and the Cochrane Review in October 2007.

RESULTS

Among 3327 articles searched, 31 articles on 22 randomized controlled trials, which included 161 045 total subjects, 88 610 in antioxidant supplement groups and 72 435 in placebo or no-intervention groups, were included in the final analyses. In a fixed-effects meta-analysis of all 22 trials, antioxidant supplements were found to have no preventive effect on cancer [relative risk (RR) 0.99; 95% confidence interval (CI) 0.96-1.03). Similar findings were observed in 12 studies on primary prevention trials (RR 1.00; 95% CI 0.97-1.04) and in nine studies on secondary prevention trials (RR 0.97; 95% CI 0.83-1.13). Further, subgroup analyses revealed no preventive effect on cancer according to type of antioxidant, type of cancer, or the methodological quality of the studies. On the other hand, the use of antioxidant supplements significantly increased the risk of bladder cancer (RR 1.52; 95% CI 1.06-2.17) in a subgroup meta-analysis of four trials.

CONCLUSIONS

The meta-analysis of randomized controlled trials indicated that there is no clinical evidence to support an overall primary and secondary preventive effect of antioxidant supplements on cancer. The effects of antioxidant supplements on human health, particularly in relation to cancer, should not be overemphasized because the use of those might be harmful for some cancer.

Receptor activator of nuclear factor kappa B ligand-mediated osteoclastogenesis is elevated in ankylosing spondylitis

OBJECTIVE

Ankylosing spondylitis (AS) is an inflammatory arthritis involving the axial skeleton. Decreased bone mineral density has also been reported in AS patients. This study sought to determine whether osteoclastogenesis and osteoclast activity are increased in AS.

METHODS

Twenty patients with AS were evaluated using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and other clinical parameters. Mononuclear cells were separated out from peripheral blood samples taken from AS patients and normal healthy controls and cultured with monocyte colony stimulating factor and receptor activator of the nuclear factor kappa B ligand (RANKL). Multi-nucleated, tartrate-resistant acid phosphatase stain-positive osteoclasts were counted after 9 days, and the areas of calcium absorption on calcium-coated plates were determined.

RESULTS

Osteoclastogenesis was significantly greater in AS patients than in normal controls (number of osteoclasts/1106 mononuclear cells, median, 518.0 vs. 362.5, p=0.036). No differences were observed between AS patients and controls in terms of calcium absorption areas or the serum concentrations of tumor necrosis factor and RANKL. Osteoclastogenesis was greater in AS patients with sacroiliac joint ankylosis than in those without. Osteoclastogenesis and the calcium absorption area were not found to be correlated with BASDAI nor with other clinical parameters including age, erythrocyte sedimentation rate, and C-reactive protein levels.

CONCLUSION

Osteoclastogenesis is elevated in AS patients, especially in those with sacroiliac joint ankylosis. Increased osteoclastogenesis may be related to osteopenia in AS patients.

Microemulsion polymerized polyaniline/montmorillonite nanocomposite and its electrorheology

Conducting polyaniline (PANI) and inorganic Na+-Montmorillonite (Na+-MMT) nanocomposite material was prepared via a microemulsion polymerization method. To observe the morphology of the as-synthesized PANI/Na+-MMT nanocomposite, SEM images were employed. D-spacing of the PANI/Na+-MMT nanocomposite obtained from the XRD was found to become wider than that of pure Na+-MMT particles due to the successful intercalation of PANI into Na+-MMT layers. The fabricated PANI/Na+-MMT nanocomposite based electrorheological (ER) fluid was prepared by dispersing the particles in insulating silicone oil. Dynamic mechanical properties of the ER fluid were investigated via an oscillatory testing method using a vertical oscillation rheometer under an applied electric field, showing typical ER behavior.

Carboxylic acid functionalized multi-walled carbon nanotube-adsorption onto poly(methyl methacrylate) microspheres

We prepared multi-walled carbon nanotube (MWNT) coated polymeric microspheres i.e., carboxylic acid functionalized MWNT (c-MWNT) adsorbed onto poly(methyl methacrylate) (PMMA) microspheres. Initially, the MWNT was functionalized with carboxylic acid functional group and PMMA microspheres were synthesized via a dispersion polymerization method separately. The c-MWNT/PMMA microspheres were then fabricated by blending technique i.e., simple mixing of c-MWNT and PMMA microspheres dispersed solutions under ultrasonication. Surface morphologies of the c-MWNT-adsorbed PMMA microspheres were observed using scanning electron microscopy (SEM). In addition, c-MWNT/PMMA microsphere suspension dispersed in silicone oil showed typical electrorheological characteristics of fibril structure under an applied electric field.

Antiviral activity of raoulic acid from Raoulia australis against Picornaviruses

RNA viruses are a major source of respiratory diseases worldwide. The lack of effective therapeutical treatment underlines the importance of research for new antiviral compounds. Raoulic acid is a principal ingredient of the plant Raoulia australis Hook. F. Antiviral assay using cytopathic effect (CPE) reduction method showed that raoulic acid possessed strong antiviral activity against human rhinovirus 2 (HRV2) with a 50% inhibition concentration (IC(50)) value of less than 0.1mug/ml, human rhinovirus 3 (HRV3) with a IC(50) value of 0.19 microg/ml, coxsackie B3 (CB3) virus with IC(50) values of 0.33 microg/ml, coxsackie B4 (CB4) virus with IC(50) values of 0.40 microg/ml, and enterovirus 71 (EV71) virus with IC(50) values of less than 0.1 microg/ml. However, the compound did not possess antiviral activity against influenza A (Flu A/PR, Flu A/WS, H1N1) and B viruses at four concentrations ranging from 0.1 to 100 microg/ml.

Cytokine array after cyclosporine treatment in rats

OBJECTIVES

Long-term treatment with cyclosporine (CsA) results in chronic nephrotoxicity, which is known to be mediated by several cytokines including transforming growth factor-betal. Cytokines are known to play an important role in innate immunity, apoptosis, angiogenesis, cell growth, and differentiation. They are known to be involved in most disease processes, including cancer, cardiac disease, and nephrotoxicity. To evaluate changes of cytokines in a rat model of CsA-induced chronic nephrotoxicity, we performed a cytokine array.

METHODS

Experiments were performed on two groups of rats; normal control group and CsA-treated group. Cytokine array in rat serum was performed using Cytokine Antibody Array I kit from RayBiotech.

RESULTS

Serum creatinine, urine creatinine, and creatinine clearance increased in the CsA-treated group. Among the several cytokines, the expressions of the lipopolysaccharide-induced CXC chemokine (LIX), monocyte chemoattractant protein 1 (MCP-1), nerve growth factor (beta-NGF), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the CsA-treated group were increased above that of cytokines in the control group. The density of the LIX in controls was 0.62, and in the CsA-treated group was 1.24. The density of the MCP-1 in controls was 0.68, and in CsA-treated, 1.43. The density of the beta-NGF in controls was 0.62, and that in CsA-treated, 1.24. The density of the TIMP-1 in controls 1.13, and in CsA-treated, 1.40.

CONCLUSIONS

Our data suggested that among several cytokines elevated levels of the LIX, MCP-1, beta-NGF, and TIMP-1 are the contributing factors to CsA-induced nephropathy.

Effects of cyclosporine on the production of the reactive oxygen species in the glial cells

OBJECTIVES

After organ transplantation, some patients suffer mild neurological symptoms such as tremor to severe complications including seizures and encephalopathy. Among the immunosuppressants, cyclosporine (CsA) can induce neurological side effects. However, the mechanisms of encephalopathy by CsA are not fully understood. We measured the production of reactive oxygen species (ROS) in the glioma cells after CsA treatment.

METHODS

CsA (2.5 mmol/L) added to glioma cells was incubated for 60 minutes at 37 degrees C. ROS production was evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2',7'-dichlorofluorescin using VICTOR3 multilabel counter.

RESULTS

CsA resulted in ROS production by glioma cells. The ROS production increased with the time of exposure to CsA.

CONCLUSIONS

These findings indicated that CsA may contribute to neurological side effects via ROS production.

The production of reactive oxygen species in tacrolimus-treated glial cells

OBJECTIVE

After organ transplantation, some patients suffer from mild neurological symptoms, such as tremor, to severe complications, including seizures and encephalopathy. These neurological side effects can be caused by immunosuppressants such as tacrolimus. However, the mechanism of encephalopathy by tacrolimus is not fully understood.

METHODS

We measured the production of reactive oxygen species (ROS) in glioma cells after tacrolimus treatment. Tacrolimus added to glioma cells was incubated for 60 minutes at 37 degrees C. The production of ROS was evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2',7'-dichlorofluorescin using VICTOR3TM multilabel counter.

RESULTS

Tacrolimus resulted in the production of the ROS in glioma cells. The production of the ROS was increased in time-dependent fashion.

CONCLUSIONS

These findings indicated that the tacrolimus may contribute the neurological side effects by ROS production.