Establishment of CT diagnostic reference levels (DRLs) for a Singapore healthcare cluster.

INTRODUCTION: The use of computed tomography (CT) in healthcare institutions has increased rapidly in recent years. The Singapore Health Services (SingHealth) cluster of healthcare institutions has taken the first step in establishing a local cluster-wide CT Diagnostic Reference Levels (DRL) in Singapore. CT dose data from each institution were collected through two primary dosimetry metrics: volume CT dose index (CTDIvol measured in mGy) and dose-length product (DLP measured in mGy.cm). METHODS: Data from 19 CT scanners in seven institutions under one of Singapore healthcare cluster were retrospectively collected and analysed. The five common adult CT examinations analysed were CT Brain (non-contrast enhanced), CT Chest (IV contrast enhanced), CT Kidney-Ureter-Bladder (CT KUB, non-contrast enhanced), CT Pulmonary Angiogram (CT PA, IV contrast enhanced) and CT Abdomen-Pelvis (CT AP, IV contrast enhanced, single phase). Median CTDIvol and DLP values for the five CT examinations from each institution were derived, with the cluster DRLs determined as the 75th percentile of the distribution of the institution median dose values. RESULTS: A total of 2413 dose data points were collected over a six-month period from June to November 2020. The cluster CT DRLs for the five CT examinations were determined to be 47 mGy and 820 mGy.cm for CT Brain, 5.4 mGy and 225 mGy.cm for CT Chest, 6.7 mGy and 248 mGy.cm for CT PA, 4.6 mGy and 190 mGy.cm for CT KUB and 6.9 mGy and 349 mGy.cm for CT AP. CONCLUSION: The establishment of the cluster CT DRLs provided individual institutions with a better understanding if their CT doses are unusually high or low, while emphasising that these DRLs are not meant as hard dose limits or constraints to follow strictly.

Percentage of intrathoracic stomach predicts operative and post-operative morbidity, persistent reflux and PPI requirement following laparoscopic hiatus hernia repair and fundoplication.

PURPOSE: Large hiatus hernias are relatively common and can be associated with adverse symptoms and serious complications. Operative repair is indicated in this patient group for symptom management and the prevention of morbidity. This study aimed to identify predictors of poor outcomes following laparoscopic hiatus hernia repair and fundoplication (LHHRaF) to aid in counselling potential surgical candidates. METHODOLOGY: A retrospective analysis was performed from a prospectively maintained, multicentre database of patients who underwent LHHRaF between 2014 and 2020. Revision procedures were excluded. Hernia size was defined as the intraoperative percentage of intrathoracic stomach, estimated by the surgeon to the nearest 10%. Predictors of outcomes were determined using a prespecified multivariate logistic regression model. RESULTS: 625 patients underwent LHHRaF between 2014 and 2020 with 443 patients included. Median age was 65 years, 62.9% were female and 42.7% of patients had ≥ 50% intrathoracic stomach. In a multivariate regression model, intrathoracic stomach percentage was predictive of operative complications (P = 0.014, OR 1.05), post-operative complications (P = 0.026, OR 1.01) and higher comprehensive complication index score (P = 0.023, OR 1.04). At 12 months it was predictive of failure to improve symptomatic reflux (P = 0.008, OR 1.02) and persistent PPI requirement (P = 0.047, OR 1.02). Operative duration and blood loss were predicted by BMI (P = 0.004 and < 0.001), Type III/IV hernias (P = 0.045 and P = 0.005) and intrathoracic stomach percentage (P = 0.009 and P < 0.001). Post-operative length of stay was predicted by age (P < 0.001) and emergency presentation (P = 0.003). CONCLUSION: In a multivariate regression model, intrathoracic stomach percentage was predictive of operative and post-operative morbidity, PPI use, and failure to improve reflux symptoms at 12 months.

Evaluating factors associated with paediatric cochlear implant outcome in four cochlear implant satellite centres in Malaysia.

INTRODUCTION: Many factors are associated with cochlear implant (CI) outcomes and various methods of assessment for auditory and speech performance outcomes in CI are available globally. The objective of this study is to identify factors relating to CI outcomes in paediatric population that suits local context. MATERIALS AND METHODS: A total of 18 factors consisted of variables which emphasise on audiological, CI service team, speech therapy, and family-related factors. These factors were then retrospectively analyzed among CI recipients. The outcome measurements of categorical auditory performance II (CAP-II) and speech intelligibility rating (SIR) were used to individually study each factor. Kruskal-Wallis H Test and Fisher Exact Test used with p-value <0.05 were considered significant. RESULTS: There were significant associations between post- CI CAP-II with type of hearing loss, hearing aid usage per day and mode of communication, attention, attending audiology and speech session, and siblings. For post-CI SIR, hearing aid usage per day, attention, mode of communication, attending audiology and speech session, initiatives, and siblings were statistically significant. CONCLUSION: The factors affecting the outcome of CI are dynamic. Some of the factors have demonstrated to be associated with the auditory and speech outcome in CI recipients while some factors failed to replicate similar findings. Further prospective research may refine the outcome of individual factors.

Effectiveness and safety of electroacupuncture for the treatment of pain after laparoscopic surgery: a systematic review.

OBJECTIVE: To evaluate the clinical effectiveness and safety of electroacupuncture for treating pain after laparoscopic surgery. METHODS: The following databases were searched (since their establishment until November 16, 2021) for randomized controlled trials (RCTs) on electro-acupuncture for pain after laparoscopic surgery: PubMed, Embase, the Cochrane Library, Web of Science, China National Knowledge Infrastructure Database, Wanfang Database, China Science and Technology Journal Database, and Chinese Biomedical Literature Database. Data were screened independently and extracted by two reviewers. Two researchers independently extracted and cross-checked data and applied the modified Jadad scale and the Cochrane-recommended assessment method to evaluate the bias risk. The Meta-analysis was conducted using RevMan5.3 software. RESULTS: Twelve RCTs enrolling 788 patients were included. (a) For postoperative 24 h visual analogue scale, five trials were included on electroacupuncture + routine analgesia therapy vs routine analgesia therapy with significance in electroacupuncture conducted after surgery [mean difference (MD) = -0.63, 95% confidence interval (CI) (-0.90, -0.37)], as well as in electroacupuncture conducted before and after surgery [MD = -1.01, 95% CI (-1.62, -0.41)] and in surgery. However, two trials were included in electroacupuncture conducted 24 h before surgery with no significant difference [MD = -0.16, 95% CI (-0.44, 0.12)]. (b) The anesthetics intake of electroacupuncture + routine analgesia therapy vs. routine analgesia therapy was significant [MD = -121.71, 95% CI (-164.92, -78.49)]. (c) The adverse effects of electroacupuncture + routine analgesia therapy vs. routine analgesia therapy were significant both in the incidence of postoperative nausea and vomiting [risk rate (RR) = 0.49, 95% CI (0.39, 0.61)] and postoperative dizziness and headache [RR = 0.14, 95% CI (0.04, 0.47)]. CONCLUSION: The evidence showed that electro-acupuncture combined with routine analgesia therapy effectively treated pain after laparoscopic surgery. However, more rigorously designed RCTs are required due to the low quality of the included studies and the incomplete outcome evaluation system.

Characteristics of bisphosphonate and non-bisphosphonate related atypical femoral fracture in a South East Asian population - Secondary analysis.

INTRODUCTION: Studies have found that not all atypical femoral fractures (AFF) are associated with bisphosphonate (BP) use. There are limited data on AFF in non-BP patients. In this study, we characterise factors associated with BP and non-BP related AFF and its mortality in a single centre in Singapore. METHODS: We conducted a cohort study of subjects above 50 years old admitted to Changi General Hospital (CGH), Singapore with fragility subtrochanteric and femoral fractures from 2009 to 2015. Using the ASBMR 2014 criteria fractures are classified into atypical and typical femoral fractures. CGH uses a nationalised electronic health record that allows review of information on patient's demographics, clinical history and previous investigations. Mortality was assessed as of 31st December 2019. RESULTS: Between 2009 and 2015, there were 3097 hip fractures, of which 393 were subtrochanteric and femoral fractures and 69 were classified as AFF by ASBMR 2014 criteria. 35 of AFF occurred in BP exposed and 34 occurred in non-BP exposed patients. There were no significant demographic differences in patients with BP and non-BP related AFF. There were also similar incidences of type 2 diabetes, rheumatoid arthritis and glucocorticoid use. Notably, there were a higher percentage of previous fragility fractures (35.3 % vs 9.4 %) in BP related AFF. Time to healing of fracture was slightly longer in BP related AFF at median (3 months vs 2 month, p = 0.02), however there were no differences in incidence of delayed healing. Mortality between BP and non-BP related AFF were similar. CONCLUSION: In a South East Asian population in Singapore, 47.8 % of AFF were found to be non-BP related. We found no major demographic and clinical differences between BP and non-BP related AFF. Mortality between BP and non-BP related AFF was similar. Further studies are needed to better understand the optimal treatment of osteoporosis in AFF prone patients in the Asian population.

Advances in respiratory protective equipment: practical experiences of CleanSpace® HALO™ by healthcare workers.

BACKGROUND: Personal protective equipment (PPE) offers protection from infections and hazardous materials. Advances in technology have seen rapid improvement of respiratory PPEs but real-world evaluations are needed to understand whether newer devices offer greater usability and overcome common barriers to correct use. AIM: To survey the user experiences of a new PPE device, CleanSpace® HALO™, in comparison to existing masks and respirators to determine advantages and disadvantages. METHODS: Frontline healthcare workers of a large healthcare provider cluster in Singapore with practical experience of using respiratory PPE, including the CleanSpace® HALO™, were surveyed. Ease of communication, comfort, usability, ability to provide care, perceived effectiveness, barriers, and enablers to respiratory PPE use were investigated. FINDINGS: A total of 93 respondents were included in the analysis. CleanSpace® HALO™ was rated highly in terms of perceived safety (92%), comfort (40%), and ease of donning and doffing (53%). CleanSpace® HALO™ was less disruptive to patient care (8%), although the ability to communicate effectively remained an obstacle (22%). Respondents also noted the incomplete facial protection provided by CleanSpace® HALO™. CONCLUSION: Respiratory protective devices are integral to effective infection control protocols, but their usefulness is limited by their impact on care delivery and incorrect use. The CleanSpace® HALO™ demonstrated advantages over existing powered air purifying respirator devices but some issues remain. Future iterations must strive to overcome communication challenges and address common side-effects. Better education is also needed to improve user confidence with CleanSpace® HALO™.

Utilisation of contrast-enhanced magnetic resonance angiography in the assessment of deep inferior epigastric artery perforator flap for breast reconstruction surgery.

AIM: To identify and characterise the ideal-sized (defined as at least 2.7 mm based on the experience of plastic surgeons at Hull Royal Infirmary) perforators using magnetic resonance angiography (MRA). The study also evaluated a presumption that perforators on the left are generally larger than on the right. MATERIALS AND METHODS: Fifty consecutive patients who had undergone MRA prior to deep inferior epigastric perforator (DIEP) reconstruction were included. MRA acquisition sequences, MRA images, radiologist reports, and surgical entry database were reviewed retrospectively. Intraoperative findings were compared. The diameter and characteristics of the perforators fulfilling the criteria of being "ideal-sized", at least 2.7 mm were collected. Wilcoxon's test was used to compare the size of the left and right perforators. RESULTS: Ninety-three ideal-sized perforators were identified (diameter of 2.8-4.2 mm). Fifty-one of these were located on the left, and 42 on the right. The left perforators were indeed larger than the right (Wilcoxon's test, p=0.017). Most of the perforators were found in the superior region and medial rows. Additionally, lateral row perforators were observed to have a shorter intramuscular course. CONCLUSION: Contrast-enhanced MRA is a useful preoperative imaging technique to locate ideal DIEPs for breast reconstruction. Perforators on the left were found to be larger than the right, and more ideal-sized perforators were located on the left.

Capacitive deionization of a RO brackish water by AC/graphene composite electrodes.

A feasibility study for water recycling and reuse of a reverse osmosis (RO) brackish wastewater by capacitive deionization (CDI) was carried out in the present work. Palm-shell wastes enriched in carbon was recycled to yield valuable activated carbon (AC) that has advantages of high surface area, high specific capacitance, and low electrical resistance as the CDI electrodes. The GAC prepared by dispersion of AC in the graphene (rGO) layers has a high surface area and electrical conductivity for CDI. The GAC electrodes have increasing electrosorption efficiencies from 1.6 to 3.0% during the repeated electrosorption-regeneration cycles under +1.2 â†’ 0 → +1.2 V while the efficiencies the AC electrodes decrease from 2.7 to 1.6%. It is clear that the GAC-based electrodes have a better electrosorption efficiency and stability in, for example, the three repeated electrosoption-regeneration cycles for CDI of the wastewater. This work also exemplifies that the AC recycled from biomass such as palm-shell wastes can be used in CDI electrodes for recycling and reuse of wastewater.

Management of asthma in adults in primary care.

Asthma is a chronic inflammatory disease of the airway which is often misdiagnosed and undertreated. Early diagnosis and vigilant asthma control are crucial to preventing permanent airway damage, improving quality of life and reducing healthcare burdens. The key approaches to asthma management should include patient empowerment through health education and self-management and, an effective patient-healthcare provider partnership.

Flexibility vs Preorganization: Direct Comparison of Binding Kinetics for a Disordered Peptide and Its Exact Preorganized Analogues.

Many intrinsically disordered proteins, which are prevalent in nature, fold only upon binding their structured partner proteins. Such proteins have been hypothesized to have a kinetic advantage over their folded, preorganized analogues in binding their partner proteins. Here we determined the effects of ligand preorganization on the kon for a biomedically important system: an intrinsically disordered p53 peptide ligand and the MDM2 protein receptor. Based on direct simulations of binding pathways, computed kon values for fully disordered and preorganized p53 peptide analogues were within error of each other, indicating little if any kinetic advantage to being disordered or preorganized for binding the MDM2 protein. We also examined the effects of increasing the concentration of MDM2 on the extent to which its mechanism of binding to the p53 peptide is induced fit vs conformational selection. Results predict that the mechanism is solely induced fit if the unfolded state of the peptide is more stable than its folded state; otherwise, the mechanism shifts from being dominated by conformational selection at low MDM2 concentration to induced fit at high MDM2 concentration. Taken together, our results are relevant to any protein binding process that involves a disordered peptide of a similar length that forms a single α-helix upon binding a partner protein. Such disorder-to-helix transitions are common among protein interactions of disordered proteins and are therefore of fundamental biological interest.

Clinical spectrum of children receiving palliative care in Malaysian Hospitals.

INTRODUCTION: Awareness for paediatric palliative care has resulted in the impetus for paediatrician-led palliative care services across Malaysia. However, there is paucity of local data on patients receiving hospital-based paediatric palliative care. We aim to review the clinical spectrum of patients referred to these services. METHODS: An observational study of children aged between 0-18 years receiving palliative care at 13 hospitals between 1st January and 31st December 2014 was carried out. RESULTS: There were 315 patients analysed, 90 (28.6%) and 46 (14.6%) were neonates and adolescents respectively. The main ICD-10 diagnostic categories for all patients were identified to be 'Congenital malformations, deformations and chromosomal abnormalities' 117 (37.1%), 'Diseases of nervous system' 76 (24.1%) and 'Neoplasms' 60 (19.0%). At referral 156 (50%) patients had holistic needs assessments. Patients with 'Diseases of nervous system' were assessed to have significantly more physical needs than the other two diagnostic categories. Majority of patients who knew of their diagnosis and prognosis were those with malignancy. Over a fifth of referrals were at their terminal admission. Of 144 who died, 111 (77.1%) had advanced care plans. There was bereavement follow-up in 98 (68.1%) patients. CONCLUSION: Patients referred for palliative care have varied diagnoses and needs. To ensure all paediatricians are competent to deliver quality care to all children, further education and training initiatives is imperative.

Goserelin toxicities and preferences for ovarian suppression method in pre-menopausal women with breast cancer.

BACKGROUND: Goserelin, a form of medical ovarian suppression, is an effective treatment for pre-menopausal women with breast cancer (PMBC). Meta-analysis data showed that similar efficacy is achieved with medical ovarian suppression and non-pharmacological ovarian suppression (NPOS) - oophorectomy or ovarian irradiation. The acceptance rate of NPOS remains low. AIMS: This study explored the reported toxicities of PMBC women and their preferred ovarian suppression method whilst on goserelin. METHODS: A postal survey consisting of 22 study-specific questions was sent to PMBC women who received goserelin at the Flinders Medical Centre. RESULTS: Nineteen women were identified from the database; 12 versus 7 women received goserelin in the adjuvant versus metastatic setting respectively. Thirteen (68.4%) responded to the survey. Women in the adjuvant cohort were more likely to report toxicities. The most common were hot flushes (100% vs 50% P = 0.033), myalgia/arthralgia (71.4% vs 16.7%, P = 0.048) and decreased libido (57/1% vs 16.7%, P = 0.135). NPOS was recalled to be offered to five (38.5%) women, with acceptance by one BRCA2 carrier. NPOS was declined initially due to fear of procedure, surgical/anaesthetic risk, invasiveness and planned future pregnancies. If given the option, upfront oophorectomy was indicated in seven (53.8%) women due to inconveniences with monthly goserelin. CONCLUSION: Half of PMBC women indicated a preference to NPOS, but only a minority recollected NPOS being discussed. Inconvenience with monthly goserelin is the main driver toward a preference of favouring NPOS. Clarification from larger trials that research patients' decision process and preferences regarding ovarian suppression is needed to validate our findings.

Targeting post-translational modifications of histones for cancer therapy.

Post-translational modifications (PTMs) on histones including acetylation, methylation, phosphorylation, citrullination, ubiquitination, ADP ribosylation, and sumoylation, play important roles in different biological events including chromatin dynamics, DNA replication, and transcriptional regulation. Aberrant histones PTMs leads to abnormal gene expression and uncontrolled cell proliferation, followed by development of cancers. Therefore, targeting the enzymes required for specific histone PTMs holds a lot of potential for cancer treatment. In this review article, we retrospect the latest studies in the regulations of acetylation, methylation, and phosphorylation of histones. We also summarize inhibitors/drugs that target these modifications for cancer treatment.

Saturated fatty acid induces cancer stem cell-like properties in human hepatoma cells.

Hepatic steatosis has been reported to be a risk factor for the development of liver cancer. The underlying mechanism for carcinogenesis remains to be elucidated. It has been postulated that cancer stem cells (CSCs) within tumor tissues are a subset of cells with stem cell properties of self-renewal and undifferentiation. The purpose of this study was to investigate the effects of a saturated fatty acid, palmitate (PA), on CSC-like properties of human hepatoma HepG2 cells. We investigated the effects of PA on HepG2 cells and primary rat hepatocytes (PRH) by exposing them to PA to induce lipid accumulation. Significant fat accumulation was observed by Oil Red O staining in cells exposed to PA, and it was accompanied by significant increase in NFκB (p65) nuclear translocation in HepG2 cells. Notably, PA significantly enhanced the sphere forming ability of HepG2 cells, but not PRH. Furthermore, PA significantly increased stemness gene expressions of Sox2 and Oct4, and sonic hedgehog (Shh) production. Notably, NFκB inhibitors, N-Acetyl-L-cysteine and pyrollidine dithiocarbamate, and a NOX inhibitor, diphenyleneiodonium, significantly attenuated PA-induced sphere forming ability of HepG2 cells. Our results suggest that lipid accumulation may not only induce pro-inflammatory responses in hepatocytes but may also activate CSC-like properties of hepatoma cells through NFκB activation.

Vigabatrin therapy implicates neocortical high frequency oscillations in an animal model of infantile spasms.

Abnormal high frequency oscillations (HFOs) in EEG recordings are thought to be reflections of mechanisms responsible for focal seizure generation in the temporal lobe and neocortex. HFOs have also been recorded in patients and animal models of infantile spasms. If HFOs are important contributors to infantile spasms then anticonvulsant drugs that suppress these seizures should decrease the occurrence of HFOs. In experiments reported here, we used long-term video/EEG recordings with digital sampling rates capable of capturing HFOs. We tested the effectiveness of vigabatrin (VGB) in the TTX animal model of infantile spasms. VGB was found to be quite effective in suppressing spasms. In 3 of 5 animals, spasms ceased after a daily two week treatment. In the other 2 rats, spasm frequency dramatically decreased but gradually increased following treatment cessation. In all animals, hypsarrhythmia was abolished by the last treatment day. As VGB suppressed the frequency of spasms, there was a decrease in the intensity of the behavioral spasms and the duration of the ictal EEG event. Analysis showed that there was a burst of high frequency activity at ictal onset, followed by a later burst of HFOs. VGB was found to selectively suppress the late HFOs of ictal complexes. VGB also suppressed abnormal HFOs recorded during the interictal periods. Thus VGB was found to be effective in suppressing both the generation of spasms and hypsarrhythmia in the TTX model. Vigabatrin also appears to preferentially suppress the generation of abnormal HFOs, thus implicating neocortical HFOs in the infantile spasms disease state.

Selective fusion of anchored droplets via changes in surfactant concentration.

We present a robust method to fuse in parallel an array of anchored droplets in a microchannel. Pairs of anchored droplets are fused by the removal of surfactant from the droplet interface by reducing the surfactant content in the flowing external oil phase. By controlling the flow of multiple oil inlets, the selective fusion of rows of droplets in a larger array is demonstrated. The technique is compatible with cells as shown with a trypan blue exclusion vitality assay. The method is easy to implement, requires no active components and is applicable to oil/water combinations where the surfactant is soluble in the external phase.

Molecular diversity of the methanotrophic bacteria communities associated with disused tin-mining ponds in Kampar, Perak, Malaysia.

In a previous study, notable differences of several physicochemical properties, as well as the community structure of ammonia oxidizing bacteria as judged by 16S rRNA gene analysis, were observed among several disused tin-mining ponds located in the town of Kampar, Malaysia. These variations were associated with the presence of aquatic vegetation as well as past secondary activities that occurred at the ponds. Here, methane oxidizing bacteria (MOB), which are direct participants in the nutrient cycles of aquatic environments and biological indicators of environmental variations, have been characterised via analysis of pmoA functional genes in the same environments. The MOB communities associated with disused tin-mining ponds that were exposed to varying secondary activities were examined in comparison to those in ponds that were left to nature. Comparing the sequence and phylogenetic analysis of the pmoA clone libraries at the different ponds (idle, lotus-cultivated and post-aquaculture), we found pmoA genes indicating the presence of type I and type II MOB at all study sites, but type Ib sequences affiliated with the Methylococcus/Methylocaldum lineage were most ubiquitous (46.7 % of clones). Based on rarefaction analysis and diversity indices, the disused mining pond with lotus culture was observed to harbor the highest richness of MOB. However, varying secondary activity or sample type did not show a strong variation in community patterns as compared to the ammonia oxidizers in our previous study.

Morphological and genetic variations of the freshwater leech, Hirudinaria spp., in Peninsular Malaysia.

In this study the genetic diversity of local freshwater leeches (Hirudinaria spp.) was inferred using mtDNA COI gene analysis and compared with the gross external variations of 26 freshwater leech specimens obtained from the wild and leech farms. Based on a neighbor-joining tree generated from 516 COI base sequences, four distinct clades of Hirudinaria were seen with interspecific genetic divergence in the range of 7.6-14.5%. The external morphological variations based on the presence of stripes, location of gonopores, and anus separated the samples into four morphologically distinct groups matching the four clades obtained from the molecular data. Two black stripes at the ventral region were observed only in specimens found clustered with clades that contained the GenBank-reported H. manillensis, whereas the brown or dark green coloration without stripes on the ventral region was seen in samples that clustered with H. javanica and H. bpling clades.

Molecular diversity of the ammonia-oxidizing bacteria community in disused tin-mining ponds located within Kampar, Perak, Malaysia.

Disused tin-mining ponds make up a significant amount of water bodies in Malaysia particularly at the Kinta Valley in the state of Perak where tin-mining activities were the most extensive, and these abundantly available water sources are widely used in the field of aquaculture and agriculture. However, the natural ecology and physicochemical conditions of these ponds, many of which have been altered due to secondary post-mining activities, remains to be explored. As ammonia-oxidizing bacteria (AOB) are directly related to the nutrient cycles of aquatic environments and are useful bioindicators of environmental variations, the focus of this study was to identify AOBs associated with disused tin-mining ponds that have a history of different secondary activities in comparison to ponds which were left untouched and remained as part of the landscape. The 16S rDNA gene was used to detect AOBs in the sediment and water sampled from the three types of disused mining ponds, namely ponds without secondary activity, ponds that were used for lotus cultivation and post-aquaculture ponds. When the varying pond types were compared with the sequence and phylogenetic analysis of the AOB clone libraries, both Nitrosomonas and Nitrosospira-like AOB were detected though Nitrosospira spp. was seen to be the most ubiquitous AOB as it was present in all ponds types. However, AOBs were not detected in the sediments of idle ponds. Based on rarefaction analysis and diversity indices, the disused mining pond with lotus culture indicated the highest richness of AOBs. Canonical correspondence analysis indicated that among the physicochemical properties of the pond sites, TAN and nitrite were shown to be the main factors that influenced the community structure of AOBs in these disused tin-mining ponds.