Faecal microbiota transplantation for treatment of recurrent or refractory Clostridioides difficile infection in Hong Kong.

INTRODUCTION: Clostridioides difficile infection (CDI) is a leading cause of healthcare-associated infection globally, causing significant morbidity and mortality. Faecal microbiota transplantation (FMT) has emerged as a promising option for recurrent and refractory CDI. This study aimed to assess the safety, efficacy, and feasibility of FMT for CDI in Hong Kong. METHODS: We conducted a single-centre, retrospective study for all consecutive cases of recurrent or refractory CDI who underwent FMT from 2013 to 2018. Clinical demographics, outcome, and safety parameters were collected. RESULTS: A total of 24 patients with recurrent or refractory CDI (median age 70 years, interquartile range=45.0-78.3 years; 67% male) were included. Over 80% had been recently hospitalised or were long-term care facility residents. Faecal microbiota transplantation was delivered by feeding tube in 11 (45.8%), oesophagogastroduodenoscopy in eight (33.3%), and colonoscopy in six (25%) of the patients. Resolution of diarrhoea without relapse within 8 weeks was achieved in 21 out of 24 patients (87.5%) after FMT. No deaths occurred within 30 days. The FMT was well tolerated and no serious adverse events attributable to FMT were reported. CONCLUSION: Our results confirm that FMT is a safe, efficacious, and feasible intervention for patients with refractory or recurrent CDI in Hong Kong. Given the increasing disease burden and the lack of effective alternatives in Hong Kong for difficult-to-treat cases of CDI, we recommend that a territory-wide FMT service be established to address increasing demand for this treatment.

Fabrication and laser patterning of polystyrene optical oxygen sensor films for lab-on-a-chip applications.

We present a novel and simple method for patterning oxygen-sensitive polystyrene thin films and demonstrate its potential for integration with microfluidic lab-on-a-chip devices. Optical oxygen sensing films composed of polystyrene with an embedded luminescent oxygen-sensitive dye present a convenient option for the measurement of oxygen levels in microfluidic and lab-on-a-chip devices; however, patterning and integrating the films with poly(dimethylsiloxane) (PDMS) microfluidic devices has proven difficult due to a residue after dry etch patterning that inhibits subsequent PDMS bonding. Our new method uses mask-less laser ablation by a commercial laser ablation system to define the outline of the structures and subsequent bulk film removal by aqueous lift-off. Because the bulk film is peeled or lifted off of the substrate rather than etched, the process is compatible with standard PDMS plasma bonding. We used ToF-SIMS analysis to investigate how laser ablation facilitates this fabrication process as well as why dry etching polystyrene inhibits PDMS plasma bonding. The results of this analysis showed evidence of chemical species formed during the laser ablation and dry etching processes that can produce these effects. Our new method's mask-less nature, simplicity, speed, and compatibility with PDMS bonding make it ideally suited for single-use lab-on-a-chip applications. To demonstrate the method's compatibility with PDMS microfluidics, we also present a demonstration of the sensors' integration into a microfluidic oxygen gradient generator device.

Acute Toxicity of Hypofractionated and Conventionally Fractionated (Chemo)Radiotherapy Regimens for Bladder Cancer: An Exploratory Analysis from the RAIDER Trial.

AIMS: Adding concurrent (chemo)therapy to radiotherapy improves outcomes for muscle-invasive bladder cancer patients. A recent meta-analysis showed superior invasive locoregional disease control for a hypofractionated 55 Gy in 20 fractions schedule compared with 64 Gy in 32 fractions. In the RAIDER clinical trial, patients undergoing 20 or 32 fractions of radical radiotherapy were randomised (1:1:2) to standard radiotherapy or to standard-dose or escalated-dose adaptive radiotherapy. Neoadjuvant chemotherapy and concomitant therapy were permitted. We report exploratory analyses of acute toxicity by concomitant therapy-fractionation schedule combination. MATERIALS AND METHODS: Participants had unifocal bladder urothelial carcinoma staged T2-T4a N0 M0. Acute toxicity was assessed (Common Terminology Criteria for Adverse Events) weekly during radiotherapy and at 10 weeks after the start of treatment. Within each fractionation cohort, non-randomised comparisons of the proportion of patients reporting treatment emergent grade 2 or worse genitourinary, gastrointestinal or other adverse events at any point in the acute period were carried out using Fisher's exact tests. RESULTS: Between September 2015 and April 2020, 345 (163 receiving 20 fractions; 182 receiving 32 fractions) patients were recruited from 46 centres. The median age was 73 years; 49% received neoadjuvant chemotherapy; 71% received concomitant therapy, with 5-fluorouracil/mitomycin C most commonly used: 44/114 (39%) receiving 20 fractions; 94/130 (72%) receiving 32 fractions. The acute grade 2+ gastrointestinal toxicity rate was higher in those receiving concomitant therapy compared with radiotherapy alone in the 20-fraction cohort [54/111 (49%) versus 7/49 (14%), P < 0.001] but not in the 32-fraction cohort (P = 0.355). Grade 2+ gastrointestinal toxicity was highest for gemcitabine, with evidence of significant differences across therapies in the 32-fraction cohort (P = 0.006), with a similar pattern but no significant differences in the 20-fraction cohort (P = 0.099). There was no evidence of differences in grade 2+ genitourinary toxicity between concomitant therapies in either the 20- or 32-fraction cohorts. CONCLUSION: Grade 2+ acute adverse events are common. The toxicity profile varied by type of concomitant therapy; the gastrointestinal toxicity rate seemed to be higher in patients receiving gemcitabine.

Risk assessment of residual DDTs in freshwater and marine fish cultivated around the Pearl River Delta, China.

Six species of freshwater fish collected from 10 fishponds in Shunde and Zhongshan, China, four species of marine fishes collected from different mariculture farms [four in Hong Kong (Tung Lung Chau, Ma Wan, Cheung Chau and Kat O) and two in mainland China (Daya Bay and Shenzhen)] together with feed (both trash fish and commercial pellets) and sediment were analyzed for DDTs. Total DDTs in freshwater fish flesh decreased in the order of: carnivores [1742 microg/kg lipid weight (l.w.)] > herbivores (165 microg/kg, l.w.) > omnivores (42.5 microg/kg, l.w.), with the highest concentration detected in mandarin fish (Siniperca chuatsi) (2641 microg/kg, l.w.). For marine fish, snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides) collected in Ma Wan contained elevated levels of total DDTs (2590 and 2034 microg/kg l.w., respectively). Trash fish used in both freshwater and marine fish farms contained significantly higher levels (86.5-641 microg/kg l.w.) (p < 0.05) of DDTs than in commercial pellets, but correlations between DDT levels in fish feed and muscle were not significant. The elevated biota-sediment accumulating factor for tilapia (Tilapia mossambicus) (24.1) indicated that accumulation of DDTs from sediment to the fish was evident. It can be concluded that trash fish should not be used for fish culture in order to lower the level of residual DDTs in fish muscle.

Interaction of higher plant (jute), electrofused bacteria and mycorrhiza on anthracene biodegradation.

The interaction of bacteria, mycorrhiza and jute (Corchotus capsulari, a higher plant) to reduce anthracene in different concentrations of spiked soils was investigated. Dominant indigenous bacterium (Pseudomonas sp.) isolated in the rhizosphere of jute was electrofused with anthracene degraders (Sphingomonas paucimobilis and Pseudomonas aeruginosa) which were able to produce different types of biosurfactants. The highest population (56 x 10(5)CFU/g) was found in the planted soil with the inoculation of mixtures of electrofused anthracene degraders after 7 days. The growth of anthracene degraders in the spiked soil was improved by gene transfer from indigenous bacteria. After 35 days, enhanced anthracene removals were observed in inoculated soils planted with jute (65.5-75.2%) compared with unplanted soil without inoculation (12.5%). The interaction of jute and electrofused S. paucimobilis enabled the greatest reduction of soil anthracene with or without the addition of P. aeruginosa. Mycorrhizal colonization was not significantly inhibited by anthracene in soils up to 150 mg/kg. Inoculation of jute with Glomus mosseae and Glomus intraradices improved plant growth and enhanced anthracene removal in the presence of electrofused S. paucimobilis.

Exposure to polybrominated diphenyl ethers associated with consumption of marine and freshwater fish in Hong Kong.

Concentrations of polybrominated diphenyl ethers (PBDEs) in market fish have not previously been reported in Hong Kong. Axial and ventral muscles from 10 each common species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for 22 PBDEs. Among the 10 freshwater fish species, spotted snakehead (Channa maculate) contained the highest level of PBDEs in ventral muscle (130 ng g(-1) wet wt.). For marine fish, bigeye (Priacanthus macracanthus) showed significantly higher levels of PBDEs (60.7 ng g(-1)wet wt. in ventral tissue) than all other marine species. The levels of PBDEs in fish samples ranged from 0.53 to 130 ng g(-1)wetwt. The tetrabrominated congener BDE-47 and pentabrominated BDE-99 were the predominant congeners, which accounted for 27% and 30%, respectively, of the total PBDEs. Daily PBDE intake was calculated according to the different fish consumption rate for Hong Kong consumers, and the results ranged from 222 to 1198 ng day(-1) for marine fish and 403-2170 ng day(-1) for freshwater fish. The daily PBDE intake from fish reported here were higher than those reported from the United States (8.94-15.7 ng day(-1)) and Europe (14-23.1 ng day(-1)).

Metal concentrations of common freshwater and marine fish from the Pearl River Delta, south China.

Sediments and fish, including tilapia (Oreochromis mossambicus), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idellus), and mandarin fish (Siniperca chuatsi) were collected from different fish ponds in the Pearl River Delta (Tanzhou, Sanjiao, Guangzhou, Shipai, Changan, and Mai Po) for the analysis of metalloids and heavy metals [arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb)]. The pollution of As in pond sediments was great; however, As in the edible parts of pond fish were within the international permissible safety levels for human consumption. Axial muscles from 10 species each of freshwater and marine fish purchased from markets in Hong Kong were also analyzed for As, Cd, Cr, Cu, Hg, Ni, Pb and Zn. Freshwater fish contained 0.24 to 2.13 mg/kg As, 0.10 to 0.17 mg/kg Cd, 0.09 to 0.36 mg/kg Cr, 0.06 to 0.35 mg/kg Cu, 0.07 to 0.34 mg/kg Hg, 0.04 to 0.36 mg/kg Ni, 0.11 to 0.52 mg/kg Pb, and 2.67 to 19.1 mg/kg Zn (wet weight). Marine fish had higher Hg and lower Pb concentrations than freshwater fish. A few fish species had average concentrations greater than the international standards for Cd and Pb established by the European Union and the China National Standard Management Department. Total Hg concentrations in 10 of 20 market fish species were generally greater than those of the World Health Organization's recommended limit of 0.2 mg/kg for at-risk groups, such as children and pregnant women. Daily intake through fish consumption of these metals were compared with the Provisional Tolerable Weekly Intake proposed by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives. There appears to be potential threat to local people from Hg contamination because of the high marine fish consumption rate (142 g/d/person).

Residual levels of DDTs and PAHs in freshwater and marine fish from Hong Kong markets and their health risk assessment.

Axial and ventral muscle from 10 each species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for dichlorodiphenyltrichloroethane (total DDTs including DDE, DDD and DDT) and polycyclic aromatic hydrocarbons (PAHs). Among the 10 freshwater fish species, rice field eel (Monopterus albus) showed significantly higher levels of DDTs in both ventral (125 ng/g wet wt) and axial muscle (127 ng/g wet wt) than the other species. The highest concentration of PAHs was detected in catfish (Clarias fuscus), with 24.8 ng/g in ventral muscle and 9.1 ng/g in axial muscle. As to marine fish, snubnose pompano (Trachinotus blochii) showed significantly higher levels of DDT and its metabolites (1018 ng/g in ventral and 409 ng/g wet wt in axial tissues) than all other marine fish species. The overall concentrations of PAHs in marine fish species were 15.5-57.0 ng/g (axial muscle) and 18.1-118 ng/g wet wt (ventral muscle) where yellow seafin (Acanthopeyrus latus) and golden threadfin bream (Nemipterus virgatus) exhibited the highest concentrations of PAHs in the axial and ventral muscles, respectively. In general, results showed that levels of PAHs in Hong Kong market fish was low and do not expect to cause any concern for human consumption. However, the levels of DDTs in fish samples ranged from 1.10 to 1018 ng/g wet wt, and based on a fish consumption rate of 142.2g/day to calculate the screening value of 14.4 ng/g wet wt for human consumption (USEPA, 2000. Guidance for assessing chemical contaminant, data for use in fish advisories, vol. 1: fish sampling and analysis, third ed. EPA 823-R-95-007. Office of Water, Washington, DC), there were 9 out of 20 (45%) muscle samples of freshwater fish species and 14 out of 20 (70%) muscle samples of marine fish species had elevated levels of DDTs exceeded the screening value. It was also suggested to use ventral muscle for detecting concentrations of persistent organic pollutants in fish.

Pollutants in Hong Kong soils: polycyclic aromatic hydrocarbons.

An extensive soil survey was carried out to study the polycyclic aromatic hydrocarbon (PAH) contaminations in 138 soil samples collected throughout Hong Kong. Results demonstrated that there were low levels of PAH contaminations (median of summation operator 16US EPA PAHs=140 microg kg(-1)) for all land uses (urban park, greening area, country park, rural area, restored landfill, agricultural farmland, orchard farm, crematorium, industrial and near highway area). However, localized hotspots were identified with summation operator 16PAH concentrations as high as 19,500 microg kg(-1) in one urban park. These findings were also confirmed by multivariate analysis. Comparison of PAH profiles showed a widespread domination of its 4-ring member. The major contribution was vehicular emissions from petroleum, and however at the hotspots, the improper disposal of used motor oils. In general, the pollution levels for all the land uses were below the recommended values for residential and general purposes stated in soil quality guidelines such as Netherlands and Denmark except certain identified hotspots. The potential health hazards imposed by these hotspots were alarming, and their existence (3 out of 138 samples) suggested that sole monitoring of atmospheric PAHs may not adequately address the hidden risks to human in urban city.

Combined effects of land reclamation, channel dredging upon the bioavailable concentration of polycyclic aromatic hydrocarbons (PAHs) in Victoria Harbour sediment, Hong Kong.

The up-to-date concentration of polycyclic aromatic hydrocarbons (PAHs) in sediment materials of Victoria Harbour was investigated so as to evaluate the pollution potential associated with the reclamation projects in Hong Kong. A total of 100 sediment samples were collected at 20 locations. Except the control point in reservoir, the PAHs concentrations were detectable levels all sites (131-628.3ng/g, dw) and such values were higher than Dutch Target and Intervention Values (the New Dutch standard in 2016). The PAHs concentration indicating that construction waste and wastewater discharges were the main pollutant sources. Results of correlation in single cell gel electrophoresis assay (comet assay) studies also revealed that the PAHs concentration was highly correlated (<0.01) with DNA migration (i.e. the length of tail moment of fish cells) in 5mg/ml of PAHs. The above observation indicates that the PAHs present in the sediment may substantially effect the marine ecosystem. Although the dredged sediment can be a useful sea-filling material for land reclamation; however, the continuing leaching of PAHs and its impact on the aquatic environment need to be studied further.

Monitoring and assessment of heavy metal contamination in a constructed wetland in Shaoguan (Guangdong Province, China): bioaccumulation of Pb, Zn, Cu and Cd in aquatic and terrestrial components.

The objective of this study is to evaluate the current status of heavy metal concentrations in constructed wetland, Shaoguan (Guangdong, China). Sediments, three wetland plants (Typha latifolia, Phragmites australis, and Cyperus malaccensis), and six freshwater fish species [Carassius auratus (Goldfish), Cirrhinus molitorella (Mud carp), Ctenopharyngodon idellus (Grass carp), Cyprinus carpio (Wild common carp), Nicholsicypris normalis (Mandarin fish), Sarcocheilichthys kiangsiensis (Minnows)] in a constructed wetland in Shaoguan were collected and analyzed for their heavy metal compositions. Levels of Pb, Zn, Cu, and Cd in sediments exceeded approximately 532, 285, 11, and 66 times of the Dutch Intervention value. From the current study, the concentrations of Pb and Zn in three plants were generally high, especially in root tissues. For fish, concentrations of all studied metals in whole body of N. mormalis were the highest among all the fishes investigated (Pb 113.4 mg/kg, dw; Zn 183.1 mg/kg, dw; Cu 19.41 mg/kg, dw; 0.846 mg/kg, dw). Heavy metal accumulation in different ecological compartments was analyzed by principle component analysis (PCA), and there is one majority of grouped heavy metals concentration as similar in composition of ecological compartment, with the Cd concentration quite dissimilar. In relation to future prospect, phytoremediation technology for enhanced heavy metal accumulation by constructed wetland is still in early stage and needs more attention in gene manipulation area.

Implementing Pharmacogenomics in Europe: Design and Implementation Strategy of the Ubiquitous Pharmacogenomics Consortium.

Despite scientific and clinical advances in the field of pharmacogenomics (PGx), application into routine care remains limited. Opportunely, several implementation studies and programs have been initiated over recent years. This article presents an overview of these studies and identifies current research gaps. Importantly, one such gap is the undetermined collective clinical utility of implementing a panel of PGx-markers into routine care, because the evidence base is currently limited to specific, individual drug-gene pairs. The Ubiquitous Pharmacogenomics (U-PGx) Consortium, which has been funded by the European Commission's Horizon-2020 program, aims to address this unmet need. In a prospective, block-randomized, controlled clinical study (PREemptive Pharmacogenomic testing for prevention of Adverse drug REactions [PREPARE]), pre-emptive genotyping of a panel of clinically relevant PGx-markers, for which guidelines are available, will be implemented across healthcare institutions in seven European countries. The impact on patient outcomes and cost-effectiveness will be investigated. The program is unique in its multicenter, multigene, multidrug, multi-ethnic, and multihealthcare system approach.

Effects of inoculation of plant growth-promoting rhizobacteria on metal uptake by Brassica juncea.

A greenhouse study was carried out with Brassica juncea to critically evaluate effects of bacterial inoculation on the uptake of heavy metals from Pb-Zn mine tailings by plants. Application of plant growth-promoting rhizobacteria, including nitrogen-fixing bacteria and phosphate and potassium solubilizers, might play an important role in the further development of phytoremediation techniques. The presence of these beneficial bacteria stimulated plant growth and protected the plant from metal toxicity. Inoculation with rhizobacteria had little influence on the metal concentrations in plant tissues, but produced a much larger above-ground biomass and altered metal bioavailability in the soil. As a consequence, higher efficiency of phytoextraction was obtained compared with control treatments.

Influence of bacteria on Pb and Zn speciation, mobility and bioavailability in soil: A laboratory study.

A soil column experiment was carried out to investigate the effects of inoculation of bacteria on metal bioavailability, mobility and potential leachability through single chemical extraction, consequential extraction and in situ soil solution extraction technologies. Results showed that bacteria inoculated, including Azotobacter chroococcum, Bacillus megaterium and Bacillus mucilaginosus, may pose both positive and negative impacts on bioavailability and mobility of heavy metals in soil, depending on the chemical nature of the metals. The activities of bacteria led to an increase of water dissolved organic carbon (DOC) concentration and a decrease of pH value, which enhanced metal mobility and bioavailability (e.g. an increase of water-soluble and HOAc-soluble Zn). On the other hand, bacteria could immobilize metals (e.g. a great reduction of water-soluble Pb) due to the adsorption by bacterial cell walls and possible sedimentation reactions with phosphate or other anions produced through bacterial metabolism.

Interactions of rice (Oryza sativa L.) and PAH-degrading bacteria (Acinetobacter sp.) on enhanced dissipation of spiked phenanthrene and pyrene in waterlogged soil.

The effects of cultivation of rice (Oryza sativa L.) and PAH-degrading bacteria (Acinetobacter sp.) separately, and in combination, on the dissipation of spiked phenanthrene and pyrene (0, 50+50, 100+100, 200+200 mg kg(-1)) in waterlogged soil were studied using pot trials. The population of introduced PAH-degrading bacteria remained at 10(5) CFU g(-1) dry soil after 20 days of treatment with Acinetobacter sp. only, but increased to 10(6) when planted with rice simultaneously. Shoot and root biomass of rice when grown alone was adversely affected by spiked PAHs, but significantly increased by 2-55% and 8-409%, respectively, when inoculated with Acinetobacter sp.. Phenanthrene and pyrene concentrations in roots ranged from 1-27 and 20-98 mg kg(-1), respectively, while their concentrations in shoots were generally lower than 0.2 mg kg(-1). The dissipation of phenanthrene was mainly due to abiotic loss as 70-78% phenanthrene was lost from the control soil at the end of 80 days, while removal of 86-87% phenanthrene had been achieved after 40 days in the treatment co-cultivated with Acinetobacter sp. and rice. Compared with the control where only 6-15% of pyrene was removed from soil, a much higher dissipation of pyrene (43-62%) was attained for the treatments co-cultivated with Acinetobacter sp. and rice at the end of 80 days. The results demonstrated that co-cultivation of rice and PAH-degrading bacteria may have a great potential to accelerate the bioremediation process of PAH-contaminated soil under waterlogged conditions.

Distribution of polycyclic aromatic hydrocarbons in soils at Guiyu area of China, affected by recycling of electronic waste using primitive technologies.

The concentration, distribution, profile and possible source of polycyclic aromatic hydrocarbons (PAHs) in soil were studied in Guiyu, an electronic waste (E-waste) recycling center, using primitive technologies in Southeast China. Sixteen USEPA priority PAHs were analyzed in 49 soil samples (0-10 cm layer) in terms of individual and total concentrations, together with soil organic matter (SOM) concentrations. The concentrations of a sum of 16 PAHs ranged from 44.8 to 3206 microgkg(-1) (dry weight basis), in the descending order of E-waste open burning sites (2065 microgkg(-1))>areas near burning sites (851microgkg(-1))>rice fields (354 microgkg(-1))>reservoir areas (125microgkg(-1)). The dominant PAHs were naphthalene, phenanthrene and fluoranthene, which were mainly derived from incomplete combustion of E-waste (e.g. wire insulations and PVC materials), and partly from coal combustion and motorcycle exhausts. All individual and total PAH concentrations were significantly correlated with SOM except for naphthalene and acenaphthylene. Principal component analysis was performed, which indicated that PAHs were mainly distributed into three groups in accordance with their ring numbers and biological and anthropogenic source. In conclusion, PAH concentrations in the Guiyu soil were affected by the primitive E-waste recycling activities.

A comparative study on metal sorption by brown seaweed.

This study compared the sorption of Ag, Cd, Co, Cd, Mn, Ni, Pb and Zn by a Ca-treated Sargassum biomass at pH 5.0, under low and high ionic strength (IS) conditions. The sorption isotherms of As [As(V)] and Cr [Cr(III) and Cr(VI)] were also determined at low IS. The isotherm data for the eight cationic metals and Cr(III) were well fitted by Langmuir equations. Generally, the maximum metal uptake (Umax) followed: Cr(III) > Pb approximately Cu > Ag approximately Zn approximately Cd > Ni approximately Mn approximately Co >> Cr(VI) >> As(V) at low IS and Pb > Cu > Co > Mn approximately Cd > Zn approximately Ag > Ni at high IS. As(V) did not bind to the seaweed at pH 5.0. The results indicated that sorption of Pb was not affected by the increasing IS, though the percentage of free Pb ions in the water was greatly reduced as predicted by the speciation model. High IS lowered Umax by 10-36% (except Co and Pb), and lowered the affinity constant of the metal by 33-91% for all cationic metals, as compared to low IS. Moreover, the removal efficiency of the cationic metals and Cr decreased exponentially with initial metal concentrations and was lower at high IS. Ion-exchange was the mechanism responsible for the cationic metal sorption onto the seaweed, and Na ion interfered with the cationic metal binding through electrostatic interaction. In conclusion, this study showed the differential binding capacity of the Sargassm biomass for different metals and oxidation states and the differential effects of IS. According to the present results, Sargassum may be considered a good biosorbent for cationic metals (especially Pb) in both low and high-salt containing wastewater.

On-chip clearing of arrays of 3-D cell cultures and micro-tissues.

Three-dimensional (3-D) cell cultures are beneficial models for mimicking the complexities of in vivo tissues, especially in tumour studies where transport limitations can complicate response to cancer drugs. 3-D optical microscopy techniques are less involved than traditional embedding and sectioning, but are impeded by optical scattering properties of the tissues. Confocal and even two-photon microscopy limit sample imaging to approximately 100-200 µm depth, which is insufficient to image hypoxic spheroid cores. Optical clearing methods have permitted high-depth imaging of tissues without physical sectioning, but they are difficult to implement for smaller 3-D cultures due to sample loss in solution exchange. In this work, we demonstrate a microfluidic platform for high-throughput on-chip optical clearing of breast cancer spheroids using the SeeDB, Clear(T2), and ScaleSQ clearing methods. Although all three methods are able to effectively clear the spheroids, we find that SeeDB and ScaleSQ more effectively clear the sample than Clear(T2); however, SeeDB induces green autofluorescence while ScaleS causes sample expansion. Our unique on-chip implementation permits clearing arrays of 3-D cultures using perfusion while monitoring the 3-D cultures throughout the process, enabling visualization of the clearing endpoint as well as monitoring of transient changes that could induce image artefacts. Our microfluidic device is compatible with on-chip 3-D cell culture, permitting the use of on-chip clearing at the endpoint after monitoring the same spheroids during their culture. This on-chip method has the potential to improve readout from 3-D cultures, facilitating their use in cell-based assays for high-content drug screening and other applications.

Phase contrast X-ray imaging of mice and rabbit lungs: a comparative study.

The significant degree of X-ray phase contrast created by air-tissue interfaces, coupled with the poor radiographic contrast of conventional chest radiographs, makes the inflated lung an ideal candidate for investigating the potential diagnostic improvement afforded by phase contrast X-ray imaging. In small animals these methods highlight the lung airways and lobe boundaries and reveal the lung tissue as a speckled intensity pattern not seen in other soft tissues. We have compared analyser-based and propagation-based phase contrast imaging modalities, together with conventional radiographic imaging, to ascertain which technique shows the greatest image enhancement for various lung sizes. The conventional radiographic image of a mouse was obtained on a Siemens Nova 3000 mammography system, whilst phase contrast images of mice and rabbit chests were acquired at the medical imaging beamline (20B2) at the SPring-8 synchrotron radiation research facility in Japan. For mice aged 1 day, 1 week and 1 month old it was determined that analyser-based imaging showed the greatest overall image contrast, however, for an adult rabbit both techniques yielded excellent contrast. The success of these methods in creating high quality images for rabbit lungs raises the possibility of improving human lung imaging using phase contrast techniques.

The residual dynamic of polycyclic aromatic hydrocarbons and organochlorine pesticides in fishponds of the Pearl River delta, South China.

Hong Kong and South China are the most developed regions within China. The industrialization in these areas has resulted in severe environmental problems. Sediment and biotic samples including tilapia (Oreochromis mossambicus), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idellus), crucian carp (Carassius auratus) and mandarin fish/fresh water grouper (Siniperca chuatsi) were collected from different fishponds in the Pearl River Delta (Tanzhou, Sanjiao, Guangzhou, Shipai, Changan and Mai Po) for the analysis of polycyclic aromatic hydrocarbons (PAHs) and organochlorine (OC) pesticides. Mandarin fish, which belongs to the highest trophic level, accumulated the highest concentrations of PAHs and DDTs among all fish species. The levels of DDTs in fish samples ranged from 1.5 to 62ng g-1 (wet wt.), with more than 30% of the fish samples exceeding the limit of 14.4ng g-1 (wet wt.) for human consumption recommended by US EPA (2000). Levels of PAHs in fish samples ranged from 1.91 to 224.03ng g-1 (wet wt.), but the potency-weighted total concentrations of PAHs in all muscle tissues were below the guideline value of 0.67ng g-1 (wet wt.) for human consumption set by US EPA (2000). The guideline value calculated was based on a tissue consumption rate of 142.2g day-1 (4-5 meals per week), which is a more protective rate for populations with a high consumption of fish, like Chinese and Asians. The effect of lipid content in PAHs and DDTs accumulation in fish tissue was not significant in general.