Multi-capillary column-ion mobility spectrometry (MCC-IMS) as a new method for the quantification of occupational exposure to sevoflurane in anaesthesia workplaces: an observational feasibility study

BACKGROUND: Occupational exposure to sevoflurane has the potential to cause health damage in hospital personnel. Workplace contamination with the substance mostly is assessed by using photoacoustic infrared spectrometry with detection limits of 10 ppbv. Multi-capillary column-ion mobility spectrometry (MCC-IMS) could be an alternative technology for the quantification of sevoflurane in the room air and could be even more accurate because of potentially lower detection limits. The aim of this study was to test the hypothesis that MCC-IMS is able to detect and monitor very low concentrations of sevoflurane (<10 ppbv) and to evaluate the exposure of hospital personnel to sevoflurane during paediatric anaesthesia and in the post anaesthesia care unit (PACU). METHODS: A MCC-IMS device was calibrated to several concentrations of sevoflurane and limits of detection (LOD) and quantification (LOQ) were calculated. Sevoflurane exposure of hospital personnel was measured at two anaesthesia workplaces and time-weighted average (TWA) values were calculated. RESULTS: The LOD was 0.0068 ppbv and the LOQ was 0.0189 ppbv. During paediatric anaesthesia the mean sevoflurane concentration was 46.9 ppbv (8.0 - 314.7 ppbv) with TWA values between 5.8 and 45.7 ppbv. In the PACU the mean sevoflurane concentration was 27.9 ppbv (8.0 – 170.2 ppbv) and TWA values reached from 8.3 to 45.1 ppbv. CONCLUSIONS: MCC-IMS shows a significantly lower LOD and LOQ than comparable methods. It is a reliable technology for monitoring sevoflurane concentrations at anaesthesia workplaces and has a particular strength in quantifying low-level contaminations of sevoflurane. The exposure of the personnel working in these areas did not exceed recommended limits and therefore adverse health effects are unlikely

Pars plana vitrectomy for diabetic macular edema. Internal limiting membrane delamination vs posterior hyaloid removal. A prospective randomized trial

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.BACKGROUND: Diabetes mellitus, as well as subsequent ocular complications such as cystoid macular edema (CME), are of fundametal socio-economic relevance. Therefore, we evaluated the influence of internal limiting membrane (ILM) removal on longterm morphological and functional outcome in patients with diabetes mellitus (DM) type 2 and chronic CME without evident vitreomacular traction. METHOD: Forty eyes with attached posterior hyaloid were included in this prospective trial and randomized intraoperatively. Prior focal (n = 31) or panretinal (n = 25) laser coagulation was permitted. Group I (n = 19 patients) underwent surgical induction of posterior vitreous detachment (PVD), group II (n = 20 patients) PVD and removal of the ILM. Eleven patients with detached posterior hyaloid (group III) were not randomized, and ILM removal was performed. One eye had to be excluded from further analysis. Examinations included ETDRS best-corrected visual acuity (BCVA), fluorescein angiography (FLA) and OCT at baseline, 3 and 6 months postoperatively. Main outcome measure was BCVA at 6 months, secondary was foveal thickness. RESULTS: Mean BCVA over 6 months remained unchanged in 85% of patients of group II, and decreased in 53% of patients of group I. Results were not statistically significant different [group I: mean decrease log MAR 95% CI (0.06; 0.32), group II: (-0.02; 0.11)]. OCT revealed a significantly greater reduction of foveal thickness following PVD with ILM removal [group I: mean change: 95% CI (-208.95 μm; -78.05 μm), group II: (-80.90 μm: +59.17 μm)]. CONCLUSION: Vitrectomy, PVD with or without ILM removal does not improve vision in patients with DM type 2 and cystoid diabetic macular edema without evident vitreoretinal traction. ILM delamination shows improved morphological results, and appears to be beneficial in eyes with preexisting PVD

The Wolbachia endosymbiont as an anti-filarial nematode target

Human disease caused by parasitic filarial nematodes is a major cause of global morbidity. The parasites are transmitted by arthropod intermediate hosts and are responsible for lymphatic filariasis (elephantiasis) or onchocerciasis (river blindness). Within these filarial parasites are intracellular alpha-proteobacteria, Wolbachia, that were first observed almost 30 years ago. The obligate endosymbiont has been recognized as a target for anti-filarial nematode chemotherapy as evidenced by the loss of worm fertility and viability upon antibiotic treatment in an extensive series of human trials. While current treatments with doxycycline and rifampicin are not practical for widespread use due to the length of required treatments and contraindications, anti-Wolbachia targeting nevertheless appears a promising alternative for filariasis control in situations where current programmatic strategies fail or are unable to be delivered and it provides a superior efficacy for individual therapy. The mechanisms that underlie the symbiotic relationship between Wolbachia and its nematode hosts remain elusive. Comparative genomics, bioinfomatic and experimental analyses have identified a number of potential interactions, which may be drug targets. One candidate is de novo heme biosynthesis, due to its absence in the genome sequence of the host nematode, Brugia malayi, but presence in Wolbachia and its potential roles in worm biology. We describe this and several additional candidate targets, as well as our approaches for understanding the nature of the host-symbiont relationship

Targeting the Wolbachia Cell Division Protein FtsZ as a New Approach for Antifilarial Therapy

Filarial nematode parasites are responsible for a number of devastating diseases in humans and animals. These include lymphatic filariasis and onchocerciasis that afflict 150 million people in the tropics and threaten the health of over one billion. The parasites possess intracellular bacteria, Wolbachia, which are needed for worm survival. Clearance of these bacteria with certain antibiotics leads to parasite death. These findings have pioneered the approach of using antibiotics to treat and control filarial infections. In the present study, we have investigated the cell division process in Wolbachia for new drug target discovery. We have identified the essential cell division protein FtsZ, which has a GTPase activity, as an attractive Wolbachia drug target. We describe the molecular characterization and catalytic properties of the enzyme and demonstrate that the GTPase activity is inhibited by the natural product, berberine, and small molecule inhibitors identified from a high-throughput screen. We also found that berberine was effective in reducing motility and reproduction in B. malayi parasites in vitro. Our results should facilitate the discovery of selective inhibitors of FtsZ as a novel antibiotic approach for controlling filarial infection

Palaeosymbiosis Revealed by Genomic Fossils of Wolbachia in a Strongyloidean Nematode

Wolbachia are common endosymbionts of terrestrial arthropods, and are also found in nematodes: the animal-parasitic filaria, and the plant-parasite Radopholus similis. Lateral transfer of Wolbachia DNA to the host genome is common. We generated a draft genome sequence for the strongyloidean nematode parasite Dictyocaulus viviparus, the cattle lungworm. In the assembly, we identified nearly 1 Mb of sequence with similarity to Wolbachia. The fragments were unlikely to derive from a live Wolbachia infection: most were short, and the genes were disabled through inactivating mutations. Many fragments were co-assembled with definitively nematode-derived sequence. We found limited evidence of expression of the Wolbachia-derived genes. The D. viviparus Wolbachia genes were most similar to filarial strains and strains from the host promiscuous clade F. We conclude that D. viviparus was infected by Wolbachia in the past, and that clade F-like symbionts may have been the source of filarial Wolbachia infections