Mitsui-7, heat-treated, and nitrogen-doped multi-walled carbon nanotubes elicit genotoxicity in human lung epithelial cells

Background

The unique physicochemical properties of multi-walled carbon nanotubes (MWCNT) have led to many industrial applications. Due to their low density and small size, MWCNT are easily aerosolized in the workplace making respiratory exposures likely in workers. The International Agency for Research on Cancer designated the pristine Mitsui-7 MWCNT (MWCNT-7) as a Group 2B carcinogen, but there was insufficient data to classify all other MWCNT. Previously, MWCNT exposed to high temperature (MWCNT-HT) or synthesized with nitrogen (MWCNT-ND) have been found to elicit attenuated toxicity; however, their genotoxic and carcinogenic potential are not known. Our aim was to measure the genotoxicity of MWCNT-7 compared to these two physicochemically-altered MWCNTs in human lung epithelial cells (BEAS-2B & SAEC).

Results

Dose-dependent partitioning of individual nanotubes in the cell nuclei was observed for each MWCNT material and was greatest for MWCNT-7. Exposure to each MWCNT led to significantly increased mitotic aberrations with multi- and monopolar spindle morphologies and fragmented centrosomes. Quantitative analysis of the spindle pole demonstrated significantly increased centrosome fragmentation from 0.024–2.4 μg/mL of each MWCNT. Significant aneuploidy was measured in a dose-response from each MWCNT-7, HT, and ND; the highest dose of 24 μg/mL produced 67, 61, and 55%, respectively. Chromosome analysis demonstrated significantly increased centromere fragmentation and translocations from each MWCNT at each dose. Following 24 h of exposure to MWCNT-7, ND and/or HT in BEAS-2B a significant arrest in the G1/S phase in the cell cycle occurred, whereas the MWCNT-ND also induced a G2 arrest. Primary SAEC exposed for 24 h to each MWCNT elicited a significantly greater arrest in the G1 and G2 phases. However, SAEC arrested in the G1/S phase after 72 h of exposure. Lastly, a significant increase in clonal growth was observed one month after exposure to 0.024 μg/mL MWCNT-HT & ND.

Conclusions

Although MWCNT-HT & ND cause a lower incidence of genotoxicity, all three MWCNTs cause the same type of mitotic and chromosomal disruptions. Chromosomal fragmentation and translocations have not been observed with other nanomaterials. Because in vitro genotoxicity is correlated with in vivo genotoxic response, these studies in primary human lung cells may predict the genotoxic potency in exposed human populations.

Electronic supplementary material

The online version of this article (10.1186/s12989-019-0318-0) contains supplementary material, which is available to authorized users.

Review article: consensus statements on therapeutic drug monitoring of anti-tumour necrosis factor therapy in inflammatory bowel diseases

BACKGROUND

Therapeutic drug monitoring (TDM) in inflammatory bowel disease (IBD) patients receiving anti-tumour necrosis factor (TNF) agents can help optimise outcomes. Consensus statements based on current evidence will help the development of treatment guidelines.

AIM

To develop evidence-based consensus statements for TDM-guided anti-TNF therapy in IBD.

METHODS

A committee of 25 Australian and international experts was assembled. The initial draft statements were produced following a systematic literature search. A modified Delphi technique was used with 3 iterations. Statements were modified according to anonymous voting and feedback at each iteration. Statements with 80% agreement without or with minor reservation were accepted.

RESULTS

22/24 statements met criteria for consensus. For anti-TNF agents, TDM should be performed upon treatment failure, following successful induction, when contemplating a drug holiday and periodically in clinical remission only when results would change management. To achieve clinical remission in luminal IBD, infliximab and adalimumab trough concentrations in the range of 3-8 and 5-12 μg/mL, respectively, were deemed appropriate. The range may differ for different disease phenotypes or treatment endpoints-such as fistulising disease or to achieve mucosal healing. In treatment failure, TDM may identify mechanisms to guide subsequent decision-making. In stable clinical response, TDM-guided dosing may avoid future relapse. Data indicate drug-tolerant anti-drug antibody assays do not offer an advantage over drug-sensitive assays. Further data are required prior to recommending TDM for non-anti-TNF biological agents.

CONCLUSION

Consensus statements support the role of TDM in optimising anti-TNF agents to treat IBD, especially in situations of treatment failure.

Comparison of true unenhanced and virtual unenhanced (VUE) attenuation values in abdominopelvic single-source rapid kilovoltage-switching spectral CT

OBJECTIVE

To assess the agreement between the true non-contrast (TNC) attenuation values of intra-abdominal structures and attenuation values obtained on virtual-unenhanced (VUE) images based on rapid kVp-switching dual-energy CT. The effects of contrast phase and patient characteristics (e.g., BMI, hematocrit, hemoglobin content) on VUE values were also investigated.

METHODS

Ninety four patients who underwent triphasic abdominal CT (liver mass protocol, n = 47; pancreas mass protocol, n = 47) between August 2014 and May 2015 were retrospectively reviewed. Unenhanced series was performed using conventional single-energy mode at 120 kVp. Late arterial and venous phase post-contrast series were obtained utilizing rapid kVp-switching dual-energy CT technique. VUE images were processed off of arterial (VUE-art) and venous (VUE-ven) phase series. Attenuation values of liver, pancreas, kidneys, adrenal glands, muscle, subcutaneous fat, aorta, IVC, and main portal vein were recorded on TNC and VUE sets of images. Attenuation values were compared using univariate linear regression and Student two-tailed paired t test.

RESULTS

There was excellent correlation between TNC, VUE-art, and VUE-ven attenuation values across all organs (p < 0.0001). Paired Student t test, however, showed significant difference between TNC and VUE-art attenuation of kidneys, right adrenal gland, paraspinal muscle, and aorta. There was also significant difference between TNC and VUE-ven attenuation of left kidney. Percentage of cases which had >10 HU difference between VUE and TNC for an individual was calculated which ranged between 13% (right kidney) and 42% (right adrenal gland).

CONCLUSION

Although the correlation between VUE and TNC attenuation values was excellent and mean difference between TNC and VUE attenuation values was negligible (ranging between -5.94 HU for paraspinal muscles to 6.2 HU in aorta), intra-patient analysis showed a considerable number of cases which had >10 HU difference between VUE and TNC. VUE-ven generally offered a better approximation of TNC values. Further optimization of post-processing algorithms might be necessary before complete replacement of TNC with VUE images.

Setting priorities for comparative effectiveness research in inflammatory bowel disease: results of an international provider survey, expert RAND panel, and patient focus groups

BACKGROUND

Comparative effectiveness research (CER) is an emerging field that compares the relative effectiveness of alternative strategies to prevent, diagnose, or treat patients who are typical of day-to-day practice. We developed a priority list of CER topics for inflammatory bowel disease (IBD).

METHODS

Following the Institute of Medicine's approach, we developed and administered a survey to gastroenterologists asking for important CER topics in IBD. Two patient focus groups were convened to solicit additional CER studies. CER topics were presented to the expert panel using the RAND/UCLA methodology. Following initial ratings, the panel met to discuss and re-rate priorities. The top 10 CER topics were identified using a point-allocation system.

RESULTS

Responses were collated into 234 CER topics across 21 categories, of which 87 were prioritized for discussion and re-rated. Disagreement regarding priorities was observed in 5 of 87 studies. We utilized a point-allocation system to prioritize the top-10 CER topics. These related to comparing the effectiveness of: biomarkers in IBD; withdrawal of anti-tumor necrosis factor (TNF) or immunomodulators for Crohn's disease in remission; mucosal healing as an endpoint of treatment; infliximab levels versus standard infliximab dosing; anti-TNF monotherapy versus combination therapy in patients failing thiopurines; safety of long-term treatment options; anti-TNF versus thiopurines for prevention of postoperative recurrence; and treatment options for steroid-refractory UC.

CONCLUSIONS

We systematically developed a list of high-priority IBD topics for CER based on a survey of gastroenterologists, expert review, and patient input. This list may guide IBD research toward the most important CER studies.

Survey of resistance of Pseudomonas aeruginosa from UK patients with cystic fibrosis to six commonly prescribed antimicrobial agents

BACKGROUND

Respiratory infection with Pseudomonas aeruginosa is very common in patients with cystic fibrosis (CF) but antimicrobial resistance rates of CF isolates across the UK are largely unknown.

METHODS

The susceptibility of 417 CF patient isolates of P aeruginosa from 17 hospitals to six commonly prescribed antibiotics were examined. Isolates were tested by an agar break point dilution method and E-tests according to British Society of Antimicrobial Chemotherapy guidelines. Genotyping of isolates was performed by XbaI DNA macrorestriction and pulsed field gel electrophoresis.

RESULTS

38% of isolates were susceptible to all of the agents tested; almost half were resistant to gentamicin compared with ceftazidime (39%), piperacillin (32%), ciprofloxacin (30%), tobramycin (10%), and colistin (3%). Approximately 40% were resistant to two or more compounds with ceftazidime in combination with gentamicin, piperacillin or ciprofloxacin being the most common cross resistances. Resistance rates were generally similar to those reported recently from the USA and Germany. A selection of resistant isolates proved to be predominantly genotypically distinct by XbaI DNA macrorestriction but six pairs from three centres had similar genotypes.

CONCLUSIONS

The level of resistance to front line antipseudomonal agents, with the exception of colistin, is disturbingly high. The prudent use of antimicrobial drugs and closer monitoring of accumulation of resistant strain populations should be actively considered.

Prevalence of dysmenorrhoea in Wellington women

A survey of 1826 women in the Wellington region was carried out. Participants were asked about their general and gynaecological health and their menstrual, contraceptive and obstetric history. Detailed questions were asked about the menstruating women's last menstrual cycle. Half the women reported some dysmenorrhoea, and 520 had 'significant period pain.' Severity, duration and timing of pain were indexed. There was maximum prevalence at 20 to 24 years and positive associations with smoking, short cycles, and moderate to severe premenstrual symptoms. There was association with method of contraception but no association with sedentary occupation or body mass index. The apparent negative relationship with parity was not significant when age, smoking and premenstrual symptomatology were taken into account.

The giving and taking of psychotropic drugs in New Zealand

The levels of compliance with psychotropic medication in three New Zealand community-based samples are reported. At younger ages psychotropics were not frequently used, only 2 percent of 15 to 34 year olds reporting use during a 24 hour period. Psychotropic drug use was most prevalent among elderly people. However, a substantial proportion, about half, of those prescribed for took lower or less frequent doses than directed.

Inorganic phosphate promotes relaxation of chemically skinned smooth muscle of guinea-pig Taenia coli

In the presence of calmodulin and phosphate and an ATP-regenerating system, Triton-treated "skinned fibers' of the Taenia coli could be made to contract and relax by step changes of Ca++ within about 30 sec. In the absence of phosphate, relaxation was slower, and during this slow relaxation tension was not maintained actively. The passive tension could be abolished by phosphate (3-6 mM). Phosphate had little effect on contractile tension but decreased the speed of contraction.