Dispersion and stability of titanium dioxide nanoparticles in aqueous suspension: effects of ultrasonication and concentration

The increasing applications of titanium dioxide (TiO(2)) nanoparticles raise concerns about their potential environmental impacts. To investigate the fate and transport of TiO(2) nanoparticles in aqueous suspension, ultrasonication is widely used for the dispersion of TiO(2) nanoparticles in laboratory-scale studies. There is a pressing need for detailed information on the dispersion and stability of TiO(2) nanoparticles. This study investigated the change of size, zeta potential, and pH of TiO(2) nanoparticles aqueous suspension under different conditions of ultrasonication and concentrations. It was found that the hydrodynamic diameter of TiO(2) nanoparticles decreased with increasing suspension concentration and remained stable for more than 1 hour after sonication, which is enough for experimental research. The pH decreased with increasing nanoparticles concentration. Ultrasonication remarkably improved zeta potential to be above 15 mV for all the samples. Therefore, 20 minutes of ultrasonication (180 W) is sufficient for the dispersion of this rutile TiO(2) nanoparticles suspension, which can remain stable for more than 1 hour. However, the optimum sonication time for TiO(2) nanoparticles dispersion is influenced by many factors, such as TiO(2) nanoparticles concentration, solution chemistry, and sonicator parameters.

Removal of titanium dioxide nanoparticles by coagulation: effects of coagulants, typical ions, alkalinity and natural organic matters

To investigate the possibility of removing titanium dioxide nanoparticles (TiO2 NPs) from water by coagulation, as well as to find the optimal coagulant and experimental conditions for TiO2 NP removal, four types of coagulant were adopted: polyferric sulfate (PFS), ferric chloride (FeCl3), polyaluminum chloride (PACl), and alum (Al2(SO4)3). It was found that the removal of TiO2 NPs by coagulation was affected by ionic strength, alkalinity, as well as types and dosages of coagulants. PFS and FeCl3 achieved much higher removal efficiency of TiO2 NPs than PACl and Al2(SO4)3 did. For 30 mg/L TiO2 NPs, a dosage of 0.3 mM PFS (as Fe) achieved 84% removal after coagulation followed by 30 min settlement. Optimal ionic strength (0.1 M NaCl or 0.03 M CaCl2) is of vital importance for the performance of PFS. Na2SO4 is unfavorable for the performance of PFS. Optimal alkalinity (0.01-0.03 M NaHCO3) is necessary for FeCl3 to remove TiO2 NPs. Natural organic matter, as represented by humic acid (HA) up to 11 mg/L, reduces the removal of TiO2 NPs by coagulation. These findings indicate that coagulation is a good option for the removal of TiO2 NPs from water, and more attention should be paid to the effects of water quality when using coagulation to remove TiO2 NPs from aqueous matrices. This provides a possible solution to alleviate the potential hazard caused by TiO2 NPs.

Differential expression and cellular localization of novel isoforms of the tendon biomarker tenomodulin

Tenomodulin (Tnmd, also called Tendin) is classified as a type II transmembrane glycoprotein and is highly expressed in developing as well as in mature tendons. Along with scleraxis (scx), Tnmd is a candidate marker gene for tenocytes. Its function is unknown, but it has been reported to have anti-angiogenic properties. Results in a knockout mouse model did not substantiate that claim. It has homology to chondromodulin-I. Single nucleotide polymorphisms of TNMD have been associated with obesity, macular degeneration, and Alzheimer's disease in patients. In the present study, three Tnmd isoforms with deduced molecular weights of 20.3 (isoform II), 25.4 (isoform III), and 37.1 (isoform I) kDa were proposed and verified by Western blot from cells with green fluorescent protein-linked, overexpressed constructs, tissue, and by qPCR of isoforms from human tissues and cultured cells. Overexpression of each Tnmd isoform followed by immunofluorescence imaging showed that isoforms I and II had perinuclear localization while isoform III was cytoplasmic. Results of qPCR demonstrated differential expression of each Tnmd isoform in patient's specimens taken from flexor carpi radialis, biceps brachii, and flexor digitorum profundus tendons. Knockdown of Tnmd increased the expression of both scleraxis (scx) and myostatin, indicating a potential negative feedback loop between Tnmd and its regulators. Knockdown of all Tnmd isoforms simultaneously also reduced tenocyte proliferation. I-TASSER protein three-dimensional conformation modeling predictions indicated each Tnmd isoform had different structures and potential functions: isoform 1, modeled as a cytosine methyltransferase; isoform 2, a SUMO-1-like SENP-1 protease; and isoform 3, an α-syntrophin, plextrin homology domain scaffolding protein. Further functional studies with each Tnmd isoform may help us to better understand regulation of tenocyte proliferation, tendon development, response to injury and strain, as well as mechanisms in tendinoses. These results may indicate novel therapeutic targets in specific tenomodulin isoforms as well as treatments for tendon diseases.

Factors influencing the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography: correlation with biopsy and radical prostatectomy specimens

OBJECTIVES

This study was designed to identify factors that influenced the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography (CETRUS).

METHODS

139 patients suspected of prostate cancer were evaluated with CETRUS followed by systematic and targeted transrectal ultrasound-guided biopsies. The degree of enhancement of the lesions was objectively measured using peak intensity with time-intensity curve analysis software. Ultrasound findings were correlated with clinical characteristics as well as biopsy and radical prostatectomy findings.

RESULTS

Prostate cancers were detected in 230 biopsy sites from 91 patients. The mean peak intensity value of prostate cancer was significantly higher than that of the benign lesions (9.82 ± 3.73 vs 7.51 ± 2.97; p<0.001), and the peak intensity value of the cancer foci varied across the prostate. The mixed model analysis revealed that the location and Gleason score of tumour foci were the influencing factors of the peak intensity value, and the former had a stronger influence upon peak intensity than the latter (p=0.000 and 0.040, respectively). However, age, prostate volume or serum prostate-specific antigen of the patient had no significant influence on the peak intensity value (p>0.05). Furthermore, the peak intensity value of tumours larger than 5 mm diameter was significantly higher than tumours of 5 mm or smaller diameter (9.28 ± 2.46 vs 6.69 ± 2.65; p<0.001).

CONCLUSIONS

The prostate cancer lesions with a higher Gleason score and larger tumour size which were located in the lateral peripheral zone (PZ) were more likely to show a marked enhancement. Lesions with lower peak intensity that are located in the medial PZ should also be treated as suspicious.

Molecular determinants of U-type inactivation in Kv2.1 channels

Kv2.1 channels exhibit a U-shaped voltage-dependence of inactivation that is thought to represent preferential inactivation from preopen closed states. However, the molecular mechanisms underlying so-called U-type inactivation are unknown. We have performed a cysteine scan of the S3-S4 and S5-P-loop linkers and found sites that are important for U-type inactivation. In the S5-P-loop linker, U-type inactivation was preserved in all mutant channels except E352C. This mutation, but not E352Q, abolished closed-state inactivation while preserving open-state inactivation, resulting in a loss of the U-shaped voltage profile. The reducing agent DTT, as well as the C232V mutation in S2, restored U-type inactivation to the E352C mutant, which suggests that residues 352C and C232 may interact to prevent U-type inactivation. The R289C mutation, in the S3-S4 linker, also reduced U-type inactivation. In this case, DTT had little effect but application of MTSET restored wild-type-like U-type inactivation behavior, suggestive of the importance of charge at this site. Kinetic modeling suggests that the E352C and R289C inactivation phenotypes largely resulted from reductions in the rate constants for transitions from closed to inactivated states. The data indicate that specific residues within the S3-S4 and S5-P-loop linkers may play important roles in Kv2.1 U-type inactivation.

Frequent methamphetamine injection predicts emergency department utilization among street-involved youth

OBJECTIVES

Methamphetamine (MA) use has been associated with health problems that commonly present in the emergency department (ED). This study sought to determine whether frequent MA injection was a risk factor for ED utilization among street-involved youth.

STUDY DESIGN

Prospective cohort study.

METHODS

Data were derived from a street-involved youth cohort known as the 'At Risk Youth Study'. Behavioural data including MA use were linked to ED records at a major inner-city hospital. Kaplan-Meier and Cox proportional hazards methods were used to determine the risk factors for ED utilization.

RESULTS

Between September 2005 and January 2007, 427 eligible participants were enrolled, among whom the median age was 21 (interquartile range 19-23) years and 154 (36.1%) were female. Within 1 year, 163 (38.2%) visited the ED, resulting in an incidence density of 53.7 per 100 person-years. ED utilization was significantly higher among frequent (i.e. ≥daily) MA injectors (log-rank P = 0.004). In multivariate analysis, frequent MA injection was associated with an increased hazard of ED utilization (adjusted hazard ratio = 1.84, 95% confidence interval 1.04-3.25; P = 0.036).

CONCLUSIONS

Street-involved youth who frequently inject MA appear to be at increased risk of ED utilization. The integration of MA-specific addiction treatment services within emergency care settings for high-risk youth is recommended.

Structural diversity of neuritogenic substances and their application perspective

Small molecular weight substances are functional, as neurotrophic factors can be developed as therapeutic drugs to treat neurodegenerative disorder. Recently, a large number of natural and synthetic neuritogenic compounds have been discovered. These compounds have various structural features, including terpenoids, lipids, alkaloids, steroid glycosides, small molecular peptides, and so on. Some of them possess not only neurotrophic properties but also neuroprotective activities. The structure-activity relationships (SARs) and mechanism of action of some important compounds have been studied intensively. Increasing experimental evidence suggests that several of these compounds can be promising candidates for drug development.

Quantum control of the spin-orbit interaction using the Autler-Townes effect

We have demonstrated quantum control of the spin-orbit interaction based on the Autler-Townes (ac-Stark) effect in a molecular system using a cw optical field. We show that the enhancement of the spin-orbit interaction between a pair of weakly interacting singlet-triplet rovibrational levels, G (1)Π(g)(v=12,J=21,f)-1 (3)Σ(g)(-)(v=1,N=21,f), separated by 750 MHz in the lithium dimer, depends on the Rabi frequency (laser power) of the control laser. The increase in the spin-orbit interaction due to the control field is observed as a change in the spin character of the individual components of the perturbed pair.

catena-Poly[[diaqua-copper(II)]-μ-hy-drox-ido-κO:O-μ-[4-(4H-1,2,4-triazol-4-yl)benzoato]-κN:N]

The title compound, [Cu(C₉H₆N₃O₂)(OH)(H₂O)₂]_n, adopts a chain motif along [010] in which the Cu^II atoms are bridged by hy­droxy groups and 4-(1,2,4-triazol-4-yl)benzoate (tab) ligands. The Cu^II atom lies on an inversion center and is six-coordinated by two N atoms from two tab ligands, two hy­droxy groups and two water mol­ecules, giving a distorted octa­hedral geometry. The hy­droxy group and the tab ligand are located on a mirror plane. One of the water H atoms is disordered over two positions with equal occupancy factors. Inter­molecular O—H⋯O hydrogen bonds extend the chains into a layer parallel to (100) and C—H⋯O hydrogen bonds connect the layers into a three-dimensional network.

Baifuzi reduces transient ischemic brain damage through an interaction with the STREX domain of BKCa channels

Stroke is a long-term disability and one of the leading causes of death. However, no successful therapeutic intervention is available for the majority of stroke patients. In this study, we explored a traditional Chinese medicine Baifuzi (Typhonium giganteum Engl.). We show, at first, that the ethanol extract of Baifuzi exerts neuroprotective effects against brain damage induced by transient global or focal cerebral ischemia in rats and mice. Second, the extract activated large-conductance Ca(2+)-activated K(+) channel (BK(Ca)) channels, and BK(Ca) channel blockade suppressed the neuroprotection of the extract, suggesting that the BK(Ca) is the molecular target of Baifuzi. Third, Baifuzi cerebroside (Baifuzi-CB), purified from its ethanol extract, activated BK(Ca) channels in a manner similar to that of the extract. Fourth, the stress axis hormone-regulated exon (STREX) domain of the BK(Ca) channel directly interacted with Baifuzi-CB, and its deletion suppressed channel activation by Baifuzi-CB. These results indicate that Baifuzi-CB activated the BK(Ca) channel through its direct interaction with the STREX domain of the channel and suggests that Baifuzi-CB merits exploration as a potential therapeutic agent for treating brain ischemia.

Contrast-enhanced ultrasonography for the detection and characterization of prostate cancer: correlation with microvessel density and Gleason score

AIM

To determine whether there is a correlation between the peak intensity of the lesion at contrast-enhanced ultrasonography and the microvessel density (MVD) and Gleason score in biopsy specimens of prostate cancer.

MATERIALS AND METHODS

Contrast-enhanced ultrasonography using cadence-contrast pulse sequence (CPS) technology was performed in 147 patients with suspected prostate cancer before biopsy. An auto-tracking contrast quantification (ACQ) software was used to analyse the peak intensity (PI) of the lesion. The Gleason score and MVD immunoreactivity were determined in the prostate biopsy specimens. Ultrasound findings were correlated with biopsy findings.

RESULTS

Prostate cancer was detected in 73 of 147 patients. The PI values of prostate cancer patients were significantly higher than those of non-malignant patients [9.81 (4.23) versus 5.69 (3.19) dB; p<0.01]. The mean (SD) PIs of prostate cancer lesions with a Gleason score of 6-9 were 7.08 (3.80), 8.65 (4.08), 9.76 (3.75), and 9.85 (4.13) dB, respectively. The PI value increased significantly with a higher Gleason score (p<0.01). The mean (SD) MVDs observed in prostate cancer lesions with a Gleason score of 6-9 were 52.50 (10.54), 56.85 (10.31), 59.91 (9.29), and 66.04 (11.82), respectively. There was a positive correlation between PI and MVD in prostate cancer, with a correlation coefficient of 0.617. No correlation was found between PI value and age, prostate specific antigen (PSA) or prostate specific antigen density (PSAD) level (p>0.05).

CONCLUSION

The PI obtained by CPS harmonic ultrasonography appears to be of value as an indicator of MVD and increases with a higher Gleason score. CPS harmonic ultrasonography could be promising as a useful imaging technique in the detection and characterization of prostate cancer.

LeERF-1, a novel AP2/ERF family gene within the B3 subcluster, is down-regulated by light signals in Lithospermum erythrorhizon

We previously showed that ethylene might be involved in the process of shikonin biosynthesis regulated by light signals. Here, we cloned a full-length cDNA of LeERF-1, a putative ethylene response factor gene, from Lithospermum erythrorhizon using the RACE (rapid amplification of cDNA ends) method. Phylogenetic analysis revealed that LeERF-1 was classified in the B3 subfamily, together with ERF1 and ORA59 of Arabidopsis. Heterologous expression of LeERF-1 in Arabidopsis showed that LeERF-1:eGFP fusion protein was precisely localised to the nucleus, implying that it might function as a transcription factor. Detailed expression analysis with real-time PCR showed that LeERF-1 was significantly down-regulated by white, blue and red light, although the inhibitory effect of red light was relatively weak compared to other light conditions. Tissue-specific expression analysis also indicated that LeERF-1 was dominantly expressed in the roots, which grow in soil in darkness. These patterns are all consistent with the effects of different light signals on regulating formation of shikonin and its derivatives, indicating that LeERF-1 might be a crucial positive regulator, like other B3 subfamily proteins (such as ORCA3 and ORA59), in regulating biosynthesis of secondary metabolites.

Management of postoperative chyloretroperitoneum in adults

Retroperitoneal chylous effusion after urological surgery is a rare and serious complication. Failure in treatment may result in cachexia, threatening the life of the patient. We present the treatment of two cases of postoperative chyloretroperitoneum with the use of somatostatin, octreotide and total parenteral nutrition. In Case 1, an 87-year-old man, a retroperitoneal lymphatic fistula occurred four days after the resection of the left kidney due to carcinoma, whereas in Case 2, a 56-year-old man, a continuous lymph fistula from the renal fossa occurred one month after resection of the right adrenal pheochromocytoma. Case 1 was treated with intravenous administration of somatostatin, and in Case 2, treatment consisted of subcutaneous administration of octreotide, in combination with total parenteral nutrition and other symptomatic therapies. In both cases, lymph exudation was terminated in about two weeks, and the patients recovered. Somatostatin therapy and total parenteral nutrition can effectively treat chyloretroperitoneum.

Cysteine-independent inhibition of the CFTR chloride channel by the cysteine-reactive reagent sodium (2-sulphonatoethyl) methanethiosulphonate

BACKGROUND AND PURPOSE

Methanethiosulphonate (MTS) reagents are used extensively to modify covalently cysteine side chains in ion channel structure-function studies. We have investigated the interaction between a widely used negatively charged MTS reagent, (2-sulphonatoethyl) methanethiosulphonate (MTSES), and the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel.

EXPERIMENTAL APPROACH

Patch clamp recordings were used to study a 'cys-less' variant of human CFTR, in which all 18 endogenous cysteine residues have been removed by mutagenesis, expressed in mammalian cell lines. Use of excised inside-out membrane patches allowed MTS reagents to be applied to the cytoplasmic face of active channels.

KEY RESULTS

Intracellular application of MTSES, but not the positively charged MTSET, inhibited the function of cys-less CFTR. Inhibition was voltage dependent, with a K(d) of 1.97 mmol x L(-1) at -80 mV increasing to 36 mmol x L(-1) at +80 mV. Inhibition was completely reversed on washout of MTSES, inconsistent with covalent modification of the channel protein. At the single channel level, MTSES caused a concentration-dependent reduction in unitary current amplitude. This inhibition was strengthened when extracellular Cl(-) concentration was decreased.

CONCLUSIONS AND IMPLICATIONS

Our results indicate that MTSES inhibits the function of CFTR in a manner that is independent of its ability to modify cysteine residues covalently. Instead, we suggest that MTSES functions as an open channel blocker that enters the CFTR channel pore from its cytoplasmic end to physically occlude Cl(-) permeation. Given the very widespread use of MTS reagents in functional studies, our findings offer a broadly applicable caveat to the interpretation of results obtained from such studies.

Surface magnetism in amine-capped ZnO nanoparticles

Magnetic behaviors of pure ZnO nanoparticles have been investigated both experimentally and theoretically. It is found that monodisperse ZnO nanoparticles wrapped with oleylamine with an average particle size of about 9.6 nm prepared by thermal decomposition do show ferromagnetic behavior with a saturation magnetization of about 34 memu g(-1) and coercive force of about 22 Oe, whereas ZnO nanoparticles with an average particle size of 5.2 nm prepared by ultrasonic irradiation without solvents show a weak ferromagnetic property with a saturation magnetization of about 0.12 memu g(-1) and coercive force of about 150 Oe at ambient temperature. First-principles calculations reveal that the 2p holes on the atoms at the surface (dangling bond of O atoms at ZnO(0001) or 2p electrons of N atom in NH(3) adsorbed on Zn(0001)) could be the source for the magnetic behavior of oxide nanoparticles.

The shine problem in hair: review of imaging methods and measures for luster

There is a need for both a better understanding of the technical drivers of shiny appearance in hair and for standard methods and measures of shine. To this end, we develop standard treatment methods for changing hair shine and examine a number of image-based measurements of luster. Using psychophysical techniques to get a perceptual reference, we find that available technical measures are difficult to use when trying to quantify the small changes in shine associated with treatment.

Dynamic gadolinium-enhanced MRI in early ischaemia of the proximal femoral epiphysis--a preliminary study

AIM

To compare the sensitivities of dynamic Gadoteridol (Gd)-enhanced magnetic resonance imaging (MRI) and conventional Gd-enhanced spin-echo (SE) T1-weighted imaging (WI) in the detection of decreased perfusion of early epiphyseal ischaemia, and to determine the contribution of metaphyseal vascularity to physeal perfusion in epiphyseal vascular occlusion by dynamic Gd-enhanced MRI.

MATERIALS AND METHODS

Twenty-eight 2-week-old piglets were divided evenly into four groups: control groups A and B, and ischaemic groups A and B (seven animals in each). In the ischaemic groups, MRI was performed bilaterally on hips in persistent hyperabduction for 30 min. In the control and ischaemic group A the piglets underwent dynamic Gd-enhanced MRI, and in control and ischaemic group B the piglets were subjected to Gd-enhanced SE T1WI.

RESULTS

In ischaemic group A, the enhancement ratio (ER) and enhancement speed (ES) of the various tissues (except the metaphysis) were significantly lower than those in control group A on dynamic Gd-enhanced MRI (p<0.05). However, in ischaemic group B, no significant decrease in the ER of each tissue was found, compared with the ER in control group B as viewed using Gd-enhanced SE T1WI (p>0.05). On dynamic Gd-enhanced MRI, the ER and ES of the physis were less than those of metaphysis in the ischaemic group A (p<0.05); however, the ER and ES of the physis were similar to those of metaphysis in control group A (p>0.05).

CONCLUSION

Dynamic Gd-enhanced MRI is more sensitive than conventional Gd-enhanced SE T1WI in the detection of early epiphyseal ischaemia. Physeal perfusion might be from the metaphysis in epiphyseal vascular occlusion.