Chromosomal genotoxicity of nitrobenzene and benzonitrile

In order to investigate the chromosomal genotoxicity of nitrobenzene and benzonitrile, we studied the induction of micronuclei (MN) by these test compounds in V79 cells, as well as effects on the formation and stability of microtubules and on motor protein functions. No cytotoxicity was seen in V79 cell cultures in terms of Neutral red uptake after 18 h treatment with up to 1 mM nitrobenzene or 1 mM benzonitrile. Subsequently, a concentration range up to 100 μM was used in the experiments on induction of MN. Both test compounds exhibit a weak, but definitely positive test result compared to the solvent (DMSO) control. Minimal effect concentrations of nitrobenzene and benzonitrile appeared as low as 0.01 μM, and no-effect-concentrations were between 0.001 and 0.005 μM. Clearly enhanced MN rates were found at 0.1 μM and higher. Both, nitrobenzene and benzonitrile, induced mostly kinetochor (CREST)-positive micronuclei, thus characterising the chromosomal effects as aneugenic. In cell-free assays, a slight effect on tubulin assembly was observed at 1 mM nitrobenzene without addition of DMSO. Higher concentrations (5 mM) led to secondary effects. In presence of 1% DMSO, nitrobenzene exerted no detectable effect on tubulin assembly up to the solubility limit in water of about 15 mM. For benzonitrile in presence of DMSO, a clear dose-response of inhibition of tubulin assembly at 37°C was seen above the no-effect-concentration of 2 mM, with an IC50 of 13 mM and protein denaturation starting above a level of about 20 mM. The nature of the effects of nitrobenzene and benzonitrile on the association of tubulin to form microtubules was confirmed by electron microscopy. Treatment by either 5 mM nitrobenzene or 13 mM benzonitrile plus 1% DMSO left the microtubular structure intact whereas 5 mM nitrobenzene, in absence of DMSO, led to irregular cluster formations. The experiments demonstrate that both nitrobenzene and benzonitrile, in millimolar concentration ranges, may lead to interference with tubulin assembly in a cell-free system. The functionality of the tubulin-kinesin motor protein system was assessed using the microtubule gliding assay. Nitrobenzene affected the gliding velocity in a concentration-dependent manner, starting at about 7.5 μM and reaching complete inhibition of motility at 30 μM, whereas benzonitrile up to 200 μM did not affect the kinesin-driven gliding velocity. The micronucleus assay data demonstrate a chromosomal endpoint of genotoxicity of nitrobenzene and benzonitrile. Aneugenic effects of both compounds occur at remarkably low concentrations, with lowest-effect-concentrations being 0.1 μM. This points to the relevance of interactions with the cellular spindle apparatus.

Genotoxicity of inorganic mercury salts based on disturbed microtubule function

This study investigated the hypothesis that the chromosomal genotoxicity of inorganic mercury results from interaction(s) with cytoskeletal proteins. Effects of Hg2+ salts on functional activities of tubulin and kinesin were investigated by determining tubulin assembly and kinesin-driven motility in cell-free systems. Hg2+ inhibits microtubule assembly at concentrations above 1 μM, and inhibition is complete at about 10 μM. In this range, the tubulin assembly is fully (up to 6 μM) or partially (∼6-10 μM) reversible. The inhibition of tubulin assembly by mercury is independent of the anion, chloride or nitrate. The no-observed-effect- concentration for inhibition of microtubule assembly in vitro was 1 μM Hg2+, the IC50 5.8 μM. Mercury(II) salts at the IC 50 concentrations partly inhibiting tubulin assembly did not cause the formation of aberrant microtubule structures. Effects of mercury salts on the functionality of the microtubule motility apparatus were studied with the motor protein kinesin. By using a "gliding assay" mimicking intracellular movement and transport processes in vitro, HgCl2 affected the gliding velocity of paclitaxel-stabilised microtubules in a clear dose-dependent manner. An apparent effect is detected at a concentration of 0.1 μM and a complete inhibition is reached at 1 μM. Cytotoxicity of mercury chloride was studied in V79 cells using neutral red uptake, showing an influence above 17 μM HgCl2. Between 15 and 20 μM HgCl2 there was a steep increase in cell toxicity. Both mercury chloride and mercury nitrate induced micronuclei concentration-dependently, starting at concentrations above 0.01 μM. CREST analyses on micronuclei formation in V79 cells demonstrated both clastogenic (CREST-negative) and aneugenic effects of Hg2+, with some preponderance of aneugenicity. A morphological effect of high Hg2+ concentrations (100 μM HgCl2) on the microtubule cytoskeleton was verified in V79 cells by immuno-fluorescence staining. The overall data are consistent with the concept that the chromosomal genotoxicity could be due to interaction of Hg2+ with the motor protein kinesin mediating cellular transport processes. Interactions of Hg 2+ with the tubulin shown by in vitro investigations could also partly influence intracellular microtubule functions leading, together with the effects on the kinesin, to an impaired chromosome distribution as shown by the micronucleus test.

Free pussy riot crazy quilt

Digital photographs sewn onto secondhand tie-dye t-shirts. The work continues Wyman's interest in exploring feminist strategies for negotiating individual and collective identiities, equality and social activism.

Weight-related differences in glucose metabolism and free fatty acid production in two South African population groups

OBJECTIVE The effects of free fatty acids (FFA), leptin, tumour necrosis factor (TNF) alpha and body fat distribution on in vivo oxidation of a glucose load were studied in two South African ethnic groups. DESIGN AND MEASUREMENTS Anthropometric and various metabolic indices were measured at fasting and during a 7h oral glucose tolerance test (OGTT). Body composition was measured using bioelectrical impedance analysis and subcutaneous and visceral fat mass was assessed using a five- and two-level CT-scan respectively. Glucose oxidation was evaluated by measuring the ratio of (13)CO(2) to (12)CO(2) in breath following ingestion of 1-(13)C-labelled glucose. SUBJECTS Ten lean black women (LBW), ten obese black women (OBW), nine lean white women (LWW) and nine obese white women (OWW) were investigated after an overnight fast. RESULTS Visceral fat levels were significantly higher (P < 0.01) in obese white than black women, despite similar body mass indexes (BMIs). There were no ethnic differences in glucose oxidation however; in the lean subjects of both ethnic groups the area under the curve (AUC) was higher than in obese subjects (P < 0.05 for both) and was found to correlate negatively with weight (r = -0.69, P < 0.01) after correcting for age. Basal TNF alpha concentrations were similar in all groups. Percentage suppression of FFAs at 30 min of the OCTT was 24 +/- 12% in OWW and - 38 +/- 23% (P < 0.05) in OBW, ie the 30 min FFA level was higher than the fasting level in the latter group. AUC for FFAs during the late postprandial period (120 - 420 min) was significantly higher in OWW than OBW (P < 0.01) and LWW (P < 0.01) and correlated positively with visceral fat mass independent of age (r = 0.78, P < 0.05) in the OWW only. Leptin levels were higher (P < 0.01) both at fasting and during the course of the OCTT in obese women from both ethnic groups compared to the lean women. CONCLUSIONS Glucose oxidation is reduced in obese subjects of both ethnic groups; inter- and intra-ethnic differences were observed in visceral fat mass and FFA production and it is possible that such differences may play a role in the differing prevalences of obesity-related disorders that have been reported in these two populations.

Design and experimental testing of air slab caps which convert commercial electron diodes into dual purpose, correction-free diodes for small field dosimetry

Purpose Two diodes which do not require correction factors for small field relative output measurements are designed and validated using experimental methodology. This was achieved by adding an air layer above the active volume of the diode detectors, which canceled out the increase in response of the diodes in small fields relative to standard field sizes. Methods Due to the increased density of silicon and other components within a diode, additional electrons are created. In very small fields, a very small air gap acts as an effective filter of electrons with a high angle of incidence. The aim was to design a diode that balanced these perturbations to give a response similar to a water-only geometry. Three thicknesses of air were placed at the proximal end of a PTW 60017 electron diode (PTWe) using an adjustable “air cap”. A set of output ratios (ORfclin Det ) for square field sizes of side length down to 5 mm was measured using each air thickness and compared to ORfclin Det measured using an IBA stereotactic field diode (SFD). k fclin, f msr Qclin,Qmsr was transferred from the SFD to the PTWe diode and plotted as a function of air gap thickness for each field size. This enabled the optimal air gap thickness to be obtained by observing which thickness of air was required such that k fclin, f msr Qclin,Qmsr was equal to 1.00 at all field sizes. A similar procedure was used to find the optimal air thickness required to make a modified Sun Nuclear EDGE detector (EDGEe) which s “correction-free” in small field relative dosimetry. In addition, the feasibility of experimentally transferring k fclin, f msr Qclin,Qmsr values from the SFD to unknown diodes was tested by comparing the experimentally transferred k fclin, f msr Qclin,Qmsr values for unmodified PTWe and EDGEe diodes to Monte Carlo simulated values. Results 1.0 mm of air was required to make the PTWe diode correction-free. This modified diode (PTWeair) produced output factors equivalent to those in water at all field sizes (5–50 mm). The optimal air thickness required for the EDGEe diode was found to be 0.6 mm. The modified diode (EDGEeair) produced output factors equivalent to those in water, except at field sizes of 8 and 10 mm where it measured approximately 2% greater than the relative dose to water. The experimentally calculated k fclin, f msr Qclin,Qmsr for both the PTWe and the EDGEe diodes (without air) matched Monte Carlo simulated results, thus proving that it is feasible to transfer k fclin, f msr Qclin,Qmsr from one commercially available detector to another using experimental methods and the recommended experimental setup. Conclusions It is possible to create a diode which does not require corrections for small field output factor measurements. This has been performed and verified experimentally. The ability of a detector to be “correction-free” depends strongly on its design and composition. A nonwater-equivalent detector can only be “correction-free” if competing perturbations of the beam cancel out at all field sizes. This should not be confused with true water equivalency of a detector.

Estrogen metabolizing enzymes in endometrium and endometriosis

BACKGROUND Estradiol (E-2) is an important promoter of the growth of both eutopic and ectopic endometrium. The findings with regard to the expression and activity of steroidogenic enzymes in endometrium of controls, in endometrium of endometriosis patients and in endometriotic lesions are not consistent. METHODS In this study, we have looked at the mRNA expression and protein levels of a range of steroidogenic enzymes [aromatase, 17 beta-hydroxysteroid dehydrogenases (17 beta-HSD) type 1, 2 and 4, estrogen sulfotransferase (EST) and steroid sulfatase (STS)l in eutopic and ectopic endometrium of patients (n = 14) with deep-infiltrative endometriosis as well as in disease-free endometrium (n = 48) using real-time PCR and immunocytochemistry. In addition, we evaluated their menstrual cycle-related expression patterns, and investigated their steroid responsiveness in explant cultures. RESULTS Aromatase and 17 beta-HSD type 1 mRNA levels were extremely low in normal human endometrium, while mRNAs for types 2 and 4 17 beta-HSD, EST and STS were readily detectable. Only 17 beta-HSD type 2 and EST genes showed sensitivity to progesterone in normal endometrium. Types 1 and 2 17 beta-HSD and STS protein was detected in normal endometrium using new polyclonal antibodies. CONCLUSIONS In endometriosis lesions, the balance is tilted in favor of enzymes producing E2. This is due to a suppression of types 2 and 4 17 beta-HSD, and an increased expression of aromatase and type 1 17 beta-HSD in ectopic endometrium.

Oral contraceptives prevent the development of endometriosis in the chicken chorioallantoic membrane model

Background: Fundamental and genetic differences between women in the endometrium may cause some to develop endometriosis, whereas others (to not. Oral contraceptives (OC) may have in effect on the endometrium, rendering the development of endometriosis less likely. Study Design: Endometrium front women using CC (OCE) and menstrual endometrium (ME) from normal cycling women were transplanted onto the chicken chorioallantoic membrane (CAM), and endometriosis-like lesion formation was evalualed. Microarray gene expression profiling was performed to identify, differentially expressed genes in the endometrium front these groups. Microarray data were validated by real-time PCR. Results: Less endometriosis-like lesions were formed after transplantation of OCE than after transplantation of ME (p<.05). Most of the differentially expressed genes belong to the TGF beta superfamily. Real-time PCR validation revealed that inhibin beta A (INHBA) expression was significantly decreased in OCE its compared to ME. Conclusion: OC use affects the characteristics Of endometrium, rendering it less potent to develop into endometriosis. (C) 2008 Elsevier Inc. All rights reserved.

Supine to standing Cobb angle change in idiopathic scoliosis : the effect of endplate pre-selection

Background Supine imaging modalities provide valuable 3D information on scoliotic anatomy, but the altered spine geometry between the supine and standing positions affects the Cobb angle measurement. Previous studies report a mean 7°-10° Cobb angle increase from supine to standing, but none have reported the effect of endplate pre-selection or whether other parameters affect this Cobb angle difference. Methods Cobb angles from existing coronal radiographs were compared to those on existing low-dose CT scans taken within three months of the reference radiograph for a group of females with adolescent idiopathic scoliosis. Reformatted coronal CT images were used to measure supine Cobb angles with and without endplate pre-selection (end-plates selected from the radiographs) by two observers on three separate occasions. Inter and intra-observer measurement variability were assessed. Multi-linear regression was used to investigate whether there was a relationship between supine to standing Cobb angle change and eight variables: patient age, mass, standing Cobb angle, Risser sign, ligament laxity, Lenke type, fulcrum flexibility and time delay between radiograph and CT scan. Results Fifty-two patients with right thoracic Lenke Type 1 curves and mean age 14.6 years (SD 1.8) were included. The mean Cobb angle on standing radiographs was 51.9° (SD 6.7). The mean Cobb angle on supine CT images without pre-selection of endplates was 41.1° (SD 6.4). The mean Cobb angle on supine CT images with endplate pre-selection was 40.5° (SD 6.6). Pre-selecting vertebral endplates increased the mean Cobb change by 0.6° (SD 2.3, range −9° to 6°). When free to do so, observers chose different levels for the end vertebrae in 39% of cases. Multi-linear regression revealed a statistically significant relationship between supine to standing Cobb change and fulcrum flexibility (p = 0.001), age (p = 0.027) and standing Cobb angle (p < 0.001). The 95% confidence intervals for intra-observer and inter-observer measurement variability were 3.1° and 3.6°, respectively. Conclusions Pre-selecting vertebral endplates causes minor changes to the mean supine to standing Cobb change. There is a statistically significant relationship between supine to standing Cobb change and fulcrum flexibility such that this difference can be considered a potential alternative measure of spinal flexibility.

Profiling high-range speeding offenders : investigating criminal history, personal characteristics, traffic offences, and crash history

This paper reports profiling information for speeding offenders and is part of a larger project that assessed the deterrent effects of increased speeding penalties in Queensland, Australia, using a total of 84,456 speeding offences. The speeding offenders were classified into three groups based on the extent and severity of an index offence: once-only low-rang offenders; repeat high-range offenders; and other offenders. The three groups were then compared in terms of personal characteristics, traffic offences, crash history and criminal history. Results revealed a number of significant differences between repeat high-range offenders and those in the other two offender groups. Repeat high-range speeding offenders were more likely to be male, younger, hold a provisional and a motorcycle licence, to have committed a range of previous traffic offences, to have a significantly greater likelihood of crash involvement, and to have been involved in multiple-vehicle crashes than drivers in the other two offender types. Additionally, when a subset of offenders’ criminal histories were examined, results revealed that repeat high-range speeding offenders were also more likely to have committed a previous criminal offence compared to once only low-range and other offenders and that 55.2% of the repeat high-range offenders had a criminal history. They were also significantly more likely to have committed drug offences and offences against order than the once only low-range speeding offenders, and significantly more likely to have committed regulation offences than those in the other offenders group. Overall, the results indicate that speeding offenders are not an homogeneous group and that, therefore, more tailored and innovative sanctions should be considered and evaluated for high-range recidivist speeders because they are a high-risk road user group.

Electrocatalytic oxidation of ascorbic acid using a single layer of gold nanoparticles immobilized on 1,6-hexanedithiol modified gold electrode

This paper describes the electrocatalytic oxidation of ascorbic acid (AA) in phosphate buffer solution by the immobilized citrate capped gold nanoparticles (AuNPs) on 1,6-hexanedithiol (HDT) modified Au electrode. X-ray photoelectron spectrum (XPS) of HDT suggests that it forms a monolayer on Au surface through one of the two single bondSH groups and the other single bondSH group is pointing away from the electrode surface. The free single bondSH groups of HDT were used to covalently attach colloidal AuNPs. The covalent attachment of AuNPs on HDT monolayer was confirmed from the observed characteristic carboxylate ion stretching modes of citrate attached with AuNPs in the infra-red reflection absorption spectrum (IRRAS) in addition to a higher reductive desorption charges obtained for AuNPs immobilized on HDT modified Au (Au/HDT/AuNPs) electrode in 0.1 M KOH when compared to HDT modified Au (Au/HDT) electrode. The electron transfer reaction of [Fe(CN)6]4−/3− was markedly hindered at the HDT modified Au (Au/HDT) electrode while it was restored with a peak separation of 74 mV after the immobilization of AuNPs on Au/HDT (Au/HDT/AuNPs) electrode indicating a good electronic communication between the immobilized AuNPs and the underlying bulk Au electrode through a HDT monolayer. The Cottrell slope obtained from the potential-step chronoamperometric measurements for the reduction of ferricyanide at Au/HDT/AuNPs was higher than that of bare Au electrode indicating the increased effective surface area of AuNPs modified electrode. The Au/HDT/AuNPs electrode exhibits excellent electrocatalytic activity towards the oxidation of ascorbic acid (AA) by enhancing the oxidation peak current to more than two times with a 210 mV negative shift in the oxidation potential when compared to a bare Au electrode. The standard heterogeneous electron transfer rate constant (ks) calculated for AA oxidation at Au/HDT/AuNPs electrode was 5.4 × 10−3 cm s−1. The oxidation peak of AA at Au/HDT/AuNPs electrode was highly stable upon repeated potential cycling. Linear calibration plot was obtained for AA over the concentration range of 1–110 μM with a correlation coefficient of 0.9950. The detection limit of AA was found to be 1 μM. The common physiological interferents such as glucose, oxalate ions and urea do not show any interference within the detection limit of AA. The selectivity of the AuNPs modified electrode was illustrated by the determination of AA in the presence of uric acid.

Better half-dead than read? The Mezzomorto cases and their implications for literary culture in the 1930s

This article focusses on the two libel cases arising from Brian Penton's review of Vivian Crockett's novel Mezzomorto for the Bulletin in 1934, viewing them as points of entry into Australian literary politics in the 1930s, and as windows on to one of the most enduring and interesting feuds in Australian literary culture, that between P.R. 'Inky' Stephensen, self-styled 'Bunyip Critic,' and Brian Penton, arch exponent of 'destructive criticism' and scourge of parochial pretension. The cases are particularly interesting for what they reveal about the evolving positions of two influential figures in Australian writing of the 1930s and 1940s. They also play in to contemporary debates about the state and status of 'literature' in Australia. And while Penton's biographer Patrick Buckridge avers that the cases did not impact on any of the larger contemporary literary issues (meaning censorship and free speech), a case may be made for the significance of the libel actions in the context of attempts to establish an industrial and cultural presence for a diverse range of Australian writing.

In-plane graphene/boron-nitride heterostructure as efficient metal-free electrocatalyst for the oxygen reduction reaction

Exploiting metal-free catalysts for the oxygen reduction reaction (ORR) and understanding their catalytic mechanisms are vital for the development of fuel cells (FCs). Our study has demonstrated that in-plane heterostructures of graphene and boron nitride (G/BN) can serve as an efficient metal-free catalyst for the ORR, in which the C-N interfaces of G/BN heterostructures act as reactive sites. The formation of water at the heterointerface is both energetically and kinetically favorable via a fourelectron pathway. Moreover, the water formed can be easily released from the heterointerface, and the catalytically active sites can be regenerated for the next reaction. Since G/BN heterostructures with controlled domain sizes have been successfully synthesized in recent reports (e.g. Nat. Nanotechnol., 2013, 8, 119), our results highlight the great potential of such heterostructures as a promising metal-free catalyst for ORR in FCs.

Effects of clear-fell harvest on bat home range.

We investigated effects of roost loss due to clear-fell harvest on bat home range. The study took place in plantation forest, inhabited by the New Zealand long-tailed bat (Chalinolobus tuberculatus), in which trees are harvested between the ages 26-32 years. We determined home ranges by radiotracking different bats in areas that had and had not been recently clear-fell harvested. Home ranges were smaller in areas that had been harvested. Adult male bats selected 20-25 year old stands within home ranges before and after harvest. Males selected edges with open unplanted areas when harvest had not occurred but no longer selected these at proportions greater than their availability post harvest, probably because they were then readily available. This is the first radiotracking study to demonstrate a change in home range size and selection concomitant with felling of large areas of plantation forest, and thus quantify negative effects of forestry operations on this speciose group. The use of smaller home ranges post-harvest may reflect smaller colony sizes and lower roost availability, both of which may increase isolation of colonies and vulnerability to local extinction.