Urban green waste bulking agent is the major source of antimicrobial resistance genes persisted in home compost, not animal manure.

Urban green waste and food waste are often used as bulking agents to prepare home compost in combination with animal manure in urban horticulture and community gardening. Although it is known that antimicrobial resistance genes (ARGs) persist in home compost, their origins have not been determined. In addition, the factors contributing to ARGs persistence remain unclear. In this study, we aim to (i) characterize the changes in the microbiome and antimicrobial resistome during the composting process of home compost using metagenomics shotgun sequencing, (ii) identify the source of the ARGs persisted in home compost using SourceTracker, and (iii) elucidate the collective effect of compost microbiome and environmental factors, including the physicochemical properties and antibiotics concentration of home compost, in contributing to ARG persistence using Procrustes analysis, co-occurrence network analysis, variation partitioning analysis, and structural equation modeling. SourceTracker analysis indicated that urban green waste bulking agent was the major source of the persisting ARGs in home compost instead of animal manure. Procrustes analysis and co-occurrence network analysis revealed a strong association between microbiome and antimicrobial resistome. Variation partitioning analysis and structural equation modeling suggested that physicochemical properties shaped the antimicrobial resistome directly and indirectly by influencing the microbiome. Our results indicated that the persistence of ARGs in home compost might be due to the succession of microbial species from the urban green waste bulking agent, and the physicochemical properties might have defined the compost environment to shape the microbiome in the compost, thus, in turn, the persisting antimicrobial resistome.

Opportunities and challenges of tackling Scope 3 "Indirect" emissions from residential hot water.

The water sector could play a major role towards a Net Zero greenhouse gas (GHG) future if Scope 3 emissions were embraced and operationalised. Significant opportunities and challenges exist in tackling Scope 3 emissions including those associated with customer hot water use. Present GHG emission reduction practices predominantly focus on Scope 1 "within utility" and Scope 2 "purchased energy" emissions. In the urban water cycle, Scope 3 "indirect" emissions dominate, and water use is only one example of Scope 3 emissions. Over 90% of all water cycle GHG emissions can be attributed to water use in residential, industrial and commercial premises, collectively some 7% of global GHG emissions. One possibility is for water utilities to actively support efficient hot water use such as new ultra-low flow shower heads. Scope 3 opportunities also offer a range of cost-effective emissions-reduction opportunities, particularly when the wider perspective of "community value" is considered and not just a "business financial perspective". Hot water efficiency is additionally essential to Net Zero carbon futures, even with decarbonised grids, because most major Net Zero roadmaps require energy efficiency gains. Scientific and management advance needed includes: accounting methodologies, clear roles, collaboration, new business models, and clear definitions. The water sector has the opportunity to play a significant role in achieving Net Zero cities. The decision how much is yet to be made.

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.

Dynamic cyclic compression modulates the chondrogenic phenotype in human chondrocytes from late stage osteoarthritis.

Human osteoarthritic chondrocytes (hOACs) are characterized by their "dedifferentiated" and catabolic phenotype and lack the ability for restoring their inherent functions by themselves. Here we investigated whether extrinsically supplemented mechanical signal via compression loading would affect the phenotype of hOACs. Specifically, we applied cyclic compression loading on cultured hOACs-collagen constructs and measured the expression of the major chondrogenic factors, cell-matrix interaction molecules and matrix degradation enzymes. Dynamic compression loading stimulates the expression and nuclear localization of sox9 in hOACs and reduces the catabolic events via downregulated expression of collagenases. These results contribute to better understanding towards mechanoregulation of hOACs.

Latex C-serum from Hevea brasiliensis induces non-apoptotic cell death in hepatocellular carcinoma cell line (HepG2).

OBJECTIVES: Latex from Hevea brasiliensis (natural rubber tree primarily cultivated for its rubber particles) has no known primary metabolic function, although its biological role is as a plant defence system. The present study has evaluated specific anti-proliferative effects of latex whole C-serum and its subfractions, on human cancer cell lines. MATERIALS AND METHODS: Cell viability assay using MTT, DNA fragmentation assay and real-time PCR were used to evaluate the cytotoxic effects of latex whole C-serum and its subfractions on the cell lines. RESULTS: MTT assay revealed very low LC(50) values, 2.0 and 280 ng/ml, for DCS and DCP treatments, respectively. DCS was proven to be more potent compared to DCP, in conferring specific anti-proliferative effects on the cancer cell lines. The study also indicated that anti-proliferative activity of pre-heated C-serum fractions diminished significantly. CONCLUSION: Although noteworthy cell death was reported, DNA fragmentation assay and real-time PCR confirmed that that induced by latex C-serum subfractions was not promoted via the classical apoptotic signalling pathway.

Anti-Candida albicans activity and brine shrimp lethality test of Hevea brasiliensis latex B-serum.

BACKGROUND AND OBJECTIVES: Hevea brasiliensis extracts could potentially be employed as a relatively low cost resource for various anti-fungal activities due to the simplicity of the extract preparation and its abundance especially in the tropical region. Latex B-serum was reported to have anti-cancer property and its specificity in anti-fungal property has not been elucidated. The present study was conducted to determine the anti-fungal activity of Hevea latex B-serum against Candida (C.) albicans (a rounded cell fungus) and Aspergillus (A.) niger (a filamentous fungus). METHODS AND RESULTS: The results showed that the anti-fungal activity of latex B-serum was specific to C. albicans but not to A. niger. The MIC value of latex B-serum for C. albicans was found to be 2.5 mg/ml. The time-killing profile showed that the growth of C. albicans was inhibited and the inhibition was prolonged throughout the tested time period. Brine shrimp toxicity test showed an LC50 of 461.0 mg/ml with latex B-serum, indicating the non-toxicity of the serum. CONCLUSION: Further purification and identification of the crude extract should point the way to bioactive compound(s) responsible for anti-Candida activity.

Anti-fungal effect of Hevea brasiliensis latex C-serum on Aspergillus niger.

OBJECTIVES: Hevea brasiliensis extract could potentially be employed as a relatively low cost resource for various anti-fungal activities due to the simplicity of latex preparation and the abundance of latex that can be obtained in rubber producing regions. The present study was aimed at examining the species specific anti-fungal property of H. brasilensis latex C-serum against Aspergillus niger. RESULTS: The results showed that the latex C-serum exerted a specific antifungal activity against Aspergillus niger, but not Candida albicans. Low toxicity of the C-serum was demonstrated in Brine Shrimp Lethality Test (BSLT) with an LC50 value of 98.4 mg/ml. CONCLUSIONS: Pending further more elaborated investigations, H. brasiliensis latex C-serum, with its species specific anti-fungal and cancer-origin cell line specific anti-proliferation properties, would probably contribute in healthcare in addition to its traditional role in polymer industry.

Technical note: acquisition of CT models for radiotherapy applications with reduced tube heating.

The potential or changing computed tomography (CT) protocols to provide data sets that generate high quality digitally reconstructed radiographs (DRRs) from scans with very low tube currents is demonstrated. DRRs were generated from CT data acquired with slice thickness of 1, 3, and 5 mm, using high current to reduce noise in axial images. These DRRs were compared to one generated from a CT scan acquired using 1 mm aperture and very low (10 mA) current. The DRR generated via this technique is comparable to that generated with high current and 1 mm aperture, and higher resolution than from the 3 and 5 mm CT scans.

A feasibility study of mutual information based setup error estimation for radiotherapy.

We have investigated a fully automatic setup error estimation method that aligns DRRs (digitally reconstructed radiographs) from a three-dimensional planning computed tomography image onto two-dimensional radiographs that are acquired in a treatment room. We have chosen a MI (mutual information)-based image registration method, hoping for robustness to intensity differences between the DRRs and the radiographs. The MI-based estimator is fully automatic since it is based on the image intensity values without segmentation. Using 10 repeated scans of an anthropomorphic chest phantom in one position and two single scans in two different positions, we evaluated the performance of the proposed method and a correlation-based method against the setup error determined by fiducial marker-based method. The mean differences between the proposed method and the fiducial marker-based method were smaller than 1 mm for translational parameters and 0.8 degree for rotational parameters. The standard deviations of estimates from the proposed method due to detector noise were smaller than 0.3 mm and 0.07 degree for the translational parameters and rotational parameters, respectively.

Genetic analysis of the CYP2D6 locus in a Hong Kong Chinese population.

BACKGROUND: The cytochrome P450 CYP2D6 enzyme debrisoquine 4-hydroxylase metabolizes many different classes of commonly used drugs, such as tricyclic antidepressants and neuroleptics. Genetic polymorphism of the CYP2D6 gene is responsible for pronounced interindividual and interracial differences in the metabolism of these drugs. The CYP2D6*10 allele and its variants are the most frequent alleles found in Orientals, and they are responsible for diminished debrisoquine 4-hydroxylase activity because of the presence of a C(188)-->T mutation in exon 1. METHODS: One hundred nineteen Hong Kong Chinese subjects were genotyped by means of allele-specific PCR, PCR, and restriction enzyme analysis for 10 CYP2D6 alleles (CYP2D6*1, *2, *4D, *5, *8/*14, *10A, *10B, *15, *16, and J9). RESULTS: CYP2D6*10B was the most prevalent allele, and CYP2D6*10/CYP2D6*10 was the most frequent genotype, representing 41.17% [corrected] of the population. CONCLUSIONS: There was no significant difference in the prevalence of the alleles analyzed between our study and the Chinese populations genotyped previously. This is the largest study in terms of the number of CYP2D6 alleles analyzed in an Oriental population and the first one conducted in a Hong Kong Chinese population.

Relative dosimetry using active matrix flat-panel imager (AMFPI) technology.

The first examination of the use of active matrix flat-panel arrays for dosimetry in radiotherapy is reported. Such arrays are under widespread development for diagnostic and radiotherapy imaging. In the current study, an array consisting of 512 x 512 pixels with a pixel pitch of 508 microm giving an area of 26 x 26 cm2 has been used. Each pixel consists of a light sensitive amorphous silicon (a-Si:H) photodiode coupled to an a-Si:H thin-film transistor. Data was obtained from the array using a dedicated electronics system allowing real-time data acquisition. In order to examine the potential of such arrays as quality assurance devices for radiotherapy beams, field profile data at photon energies of 6 and 15 MV were obtained as a function of field size and thickness of overlying absorbing material (solid water). Two detection configurations using the array were considered: a configuration (similar to the imaging configuration) in which an overlying phosphor screen is used to convert incident radiation to visible light photons which are detected by the photodiodes; and a configuration without the screen where radiation is directly sensed by the photodiodes. Compared to relative dosimetry data obtained with an ion chamber, data taken using the former configuration exhibited significant differences whereas data obtained using the latter configuration was generally found to be in close agreement. Basic signal properties, which are pertinent to dosimetry, have been investigated through measurements of individual pixel response for fluoroscopic and radiographic array operation. For signal levels acquired within the first 25% of pixel charge capacity, the degree of linear response with dose was found to be better than 99%. The independence of signal on dose rate was demonstrated by means of stability of pixel response over the range of dose rates allowed by the radiation source (80-400 MU/min). Finally, excellent long-term stability in pixel response, extending over a 2 month period, was observed.

A mathematical model for correcting patient setup errors using a tilt and roll device.

An algorithm is presented for determining how to adjust the actuators of a tilt and roll table. The algorithm is based on a geometrical model of the table, which was designed with six degrees of freedom. This design and algorithm allows complete translational and rotational corrections to be applied to the target volume position on a daily basis.

Computerized analysis of mammographic microcalcifications in morphological and texture feature spaces.

We are developing computerized feature extraction and classification methods to analyze malignant and benign microcalcifications on digitized mammograms. Morphological features that described the size, contrast, and shape of microcalcifications and their variations within a cluster were designed to characterize microcalcifications segmented from the mammographic background. Texture features were derived from the spatial gray-level dependence (SGLD) matrices constructed at multiple distances and directions from tissue regions containing microcalcifications. A genetic algorithm (GA) based feature selection technique was used to select the best feature subset from the multi-dimensional feature spaces. The GA-based method was compared to the commonly used feature selection method based on the stepwise linear discriminant analysis (LDA) procedure. Linear discriminant classifiers using the selected features as input predictor variables were formulated for the classification task. The discriminant scores output from the classifiers were analyzed by receiver operating characteristic (ROC) methodology and the classification accuracy was quantified by the area, Az, under the ROC curve. We analyzed a data set of 145 mammographic microcalcification clusters in this study. It was found that the feature subsets selected by the GA-based method are comparable to or slightly better than those selected by the stepwise LDA method. The texture features (Az = 0.84) were more effective than morphological features (Az = 0.79) in distinguishing malignant and benign microcalcifications. The highest classification accuracy (Az = 0.89) was obtained in the combined texture and morphological feature space. The improvement was statistically significant in comparison to classification in either the morphological (p = 0.002) or the texture (p = 0.04) feature space alone. The classifier using the best feature subset from the combined feature space and an appropriate decision threshold could correctly identify 35% of the benign clusters without missing a malignant cluster. When the average discriminant score from all views of the same cluster was used for classification, the Az value increased to 0.93 and the classifier could identify 50% of the benign clusters at 100% sensitivity for malignancy. Alternatively, if the minimum discriminant score from all views of the same cluster was used, the Az value would be 0.90 and a specificity of 32% would be obtained at 100% sensitivity. The results of this study indicate the potential of using combined morphological and texture features for computer-aided classification of microcalcifications.

A tilt and roll device for automated correction of rotational setup errors.

A tilt and roll device has been developed to add two additional degrees of freedom to an existing treatment table. This device allows computer-controlled rotational motion about the inferior-superior and left-right patient axes. The tilt and roll device comprises three supports between the tabletop and base. An automotive type universal joint welded to the end of a steel pipe supports the center of the table. Two computer-controlled linear electric actuators utilizing high accuracy stepping motors support the foot of table and control the tilt and roll of the tabletop. The current system meets or exceeds all pre-design specifications for precision, weight capacity, rigidity, and range of motion.

Improvement of CT-based treatment-planning models of abdominal targets using static exhale imaging.

PURPOSE: CT-based models of the patient that do not account for the motion of ventilation may not accurately predict the shape and position of critical abdominal structures. Respiratory gating technology for imaging and treatment is not yet widely available. The purpose of the current study is to explore an intermediate step to improve the veracity of the patient model and reduce the treated volume by acquiring the CT data with the patients holding their breath at normal exhale. METHODS AND MATERIALS: The ventilatory time courses of diaphragm movement for 15 patients (with no special breathing instructions) were measured using digitized movies from the fluoroscope during simulation. A subsequent clinical protocol was developed for treatment based on exhale CT models. CT scans (typically 3.5-mm slice thickness) were acquired at normal exhale using a spiral scanner. The scan volume was divided into two to three segments, to allow the patient to breathe in between. Margins were placed about intrahepatic target volumes based on the ventilatory excursion inferior to the target, and on only the reproducibility of exhale position superior to the target. RESULTS: The average patient's diaphragm remained within 25% of the range of ventilatory excursion from the average exhale position for 42% of the typical breathing cycle, and within 25% of the range from the average inhale position for 15% of the cycle. The reproducibility of exhale position over multiple breathing cycles was 0.9 mm (2sigma), as opposed to 2.6 mm for inhale. Combining the variation of exhale position and the uncertainty in diaphragm position from CT slices led to typical margins of 10 mm superior to the target, and 19 mm inferior to the target, compared to margins of 19 mm in both directions under our prior protocol of margins based on free-breathing CT studies. For a typical intrahepatic target, these smaller volumes resulted in a 3.6% reduction in Veff for the liver. Analysis of portal films shows proper target coverage for patients treated based on exhale modeled plans. CONCLUSIONS: Modeling abdominal treatments at exhale, while not realizing all the gains of gated treatments, provides an immediate reduction in the volume of normal tissue treated, and improved reliability of patient data for NTCP modeling, when compared to current "free breathing" CT models of patients.

Measurement of backscatter to the monitor chamber of medical accelerators using target charge.

A simple noninvasive method is described for determining the backscatter to a monitor chamber of a medical accelerator based on the measurement of charge deposited in the target. This method is compared quantitatively to the more elaborate telescopic method for photon beams of 6 MV and 15 MV on linear accelerators having mica and Kapton monitor chambers. The new target charge method gives results consistent with the telescopic method to within 0.3%.

A room-based diagnostic imaging system for measurement of patient setup.

A room-based diagnostic x-ray imaging system for routine measurement of radiotherapy patient orientation has been developed. The system consists of a pair of room-mounted x-ray tubes and a portable imager consisting of an orthogonal pair of phosphor screens, a mirror/lens system, a CCD camera, and computer software for comparing images of the patient to reference images. Orthogonal pairs of images can be acquired quickly and with relatively little exposure, allowing correction of patient setup on a daily basis. This could limit patient setup error to the uncertainty in the measurement and repositioning processes, a potentially significant improvement over the present standard.