8-Hydroxyquinoline Series Exerts Bactericidal Activity against Mycobacterium tuberculosis Via Copper-Mediated Toxicity.

New drugs and mechanisms of action targeting Mycobacterium tuberculosis are urgently needed to solve the global pandemic of tuberculosis. We previously demonstrated that the 8-hydroxyquinoline series has rapid bactericidal activity against M. tuberculosis. In this work, we determined that the activity of the 8HQ series is potentiated by copper ions and that the activity is dependent on copper since activity was reduced when copper was depleted from the medium. We determined that exposure to 8HQs led to an increase in intracellular copper. The increase in copper ions was specific since we saw no changes for other metal cations (zinc, iron, magnesium, manganese, or calcium). We observed the transient generation of reactive oxygen species after 8HQ exposure which disappeared by 24 h. Inhibition of growth could be partially relieved by scavenging hydroxyl radicals. We excluded the possibility that 8HQs are toxic by DNA intercalation. We screened a panel of hypomorph strains and identified sensitized strains. The pattern of sensitized strains did not suggest a specific target, but metalloenzymes, proteins with Fe-S clusters, and cell envelope biosynthetic enzymes were highlighted. These data suggest that 8HQs do not have a specific intracellular target, but act as copper ionophores, and that the mode of action is via copper-dependent toxicity.

Endoscopic Resection of Distal Femoral Exostosis That Causes Distal Iliotibial Band Syndrome.

Distal iliotibial band (ITB) syndrome is the most common cause of lateral knee pain in runners. If the ITB is too tight, the repetitive knee flexion associated with sports may lead to compression of the vascularized fat pad in the sub-ITB space or development of sub-ITB adventitious bursitis as the band crosses over the lateral femoral epicondyle and the ITB itself is normal. Distal ITB syndrome usually responds to conservative treatment. The presence of any underlying causes, for example, exostosis at the sub-ITB space, should be explored in recalcitrant cases of distal ITB syndrome. Although open surgical excision is the treatment of choice for extra-articular exostosis, the surgical risk and complication rates have been reported as high as 13%. Endoscopic resection of extra-articular exostosis has been proposed to reduce the complication rates. The purpose of this technical note is to describe the details of arthroscopic management of endoscopic resection of distal femoral exostosis that causes distal ITB syndrome.

KpsS1 Mediates the Glycosylation of Pseudaminic Acid in Acinetobacter Baumannii.

Pseudaminic acid (Pse) is found in the polysaccharide structures of the cell surface of various Gram-negative pathogenic bacteria including Acinetobacter baumannii and considered as an important component of cell surface glycans including oligosaccharides and glycoproteins. However, the glycosyltransferase that is responsible for the Pse glycosylation in A. baumannii remains unknown yet. In this study, through comparative genomics analysis of Pse-positive and negative A. baumannii clinical isolates, we identified a potential glycosyltransferase, KpsS1, located right downstream of the Pse biosynthesis genetic locus. Deletion of this gene in an Pse-positive A. baumannii strain, Ab8, impaired the glycosylation of Pse to the surface CPS and proteins, while the gene knockout strain, Ab8ΔkpsS1, could still produce Pse with 2.86 folds higher amount than that of Ab8. Furthermore, impairment of Pse glycosylation affected the morphology and virulence potential of A. baumannii, suggesting the important role of this protein. This study will provide insights into the further understanding of Pse in bacterial physiology and pathogenesis.

Investigation on the substrate specificity and N-substitution tolerance of PseF in catalytic transformation of pseudaminic acids to CMP-Pse derivatives.

Pseudaminic acid (Pse) belongs to a class of bacterial non-2-ulosonic acids, and has been implicated in bacterial infection and immune evasion. Various Pse structures with diverse N-substitutions have been identified in pathogenic bacterial strains like Pseudomonas aeruginosa, Campylobacter jejuni, and Acinetobacter baumannii. In this study, we successfully synthesized three new Pse species, including Pse5Ac7Fo, Pse5Ac7(3RHb) and Pse7Fo5(3RHb) using chemical methods. Furthermore, we investigated the substrate specificity of cytidine 5'-monophosphate (CMP)-Pse synthetase (PseF), resulting in the production of N-modified CMP-Pse derivatives (CMP-Pses). It was found that PseF was promiscuous with the Pse substrate and could tolerate different modifications at the two nitrogen atoms. This study provides valuable insights into the incorporation of variable N-substitutions in the Pse biosynthetic pathway.

Discovery of a Monoclonal Antibody That Targets Cell-Surface Pseudaminic Acid of Acinetobacter baumannii with Direct Bactericidal Effect.

The therapeutic effects of antibodies include neutralization of pathogens, activation of the host complement system, and facilitation of phagocytosis of pathogens. However, antibody alone has never been shown to exhibit bactericidal activity. In this study, we developed a monoclonal antibody that targets the bacterial cell surface component Pseudaminic acid (Pse). This monoclonal antibody, Pse-MAB1, exhibited direct bactericidal activity on Acinetobacter baumannii strains, even in the absence of the host complements or other immune factors, and was able to confer a protective effect against A. baumannii infections in mice. This study provides new insight into the potential of developing monoclonal antibody-based antimicrobial therapy of multidrug resistant bacterial infections, especially those which occurred among immunocompromised patients.

Drivers of arthropod biodiversity in an urban ecosystem.

Our world is becoming increasingly urbanized with a growing human population concentrated around cities. The expansion of urban areas has important consequences for biodiversity, yet the abiotic drivers of biodiversity in urban ecosystems have not been well characterized for the most diverse group of animals on the planet, arthropods. Given their great diversity, comparatively small home ranges, and ability to disperse, arthropods make an excellent model for studying which factors can most accurately predict urban biodiversity. We assessed the effects of (i) topography (distance to natural areas and to ocean) (ii) abiotic factors (mean annual temperature and diurnal range), and (iii) anthropogenic drivers (land value and amount of impervious surface) on the occurrence of six arthropod groups represented in Malaise trap collections run by the BioSCAN project across the Greater Los Angeles Area. We found striking heterogeneity in responses to all factors both within and between taxonomic groups. Diurnal temperature range had a consistently negative effect on occupancy but this effect was only significant in Phoridae. Anthropogenic drivers had mixed though mostly insignificant effects, as some groups and species were most diverse in highly urbanized areas, while other groups showed suppressed diversity. Only Phoridae was significantly affected by land value, where most species were more likely to occur in areas with lower land value. Los Angeles can support high regional arthropod diversity, but spatial community composition is highly dependent on the taxonomic group.

Defining the fit and ideal entry site of the fibula rod system--a computed tomography based study in elderly patients with lower limb infections, vascular diseases or tumors.

OBJECTIVES: To determine the configuration of the distal fibula anatomy and the fitness of the Fibula Rod System (Acumed®, Hillsboro, Oregon) in a series of fibula models and to determine the optimal entry site of the rod. METHODS: Consecutive series of computed tomography (CT) of tibias and fibulae with no fracture or deformity were converted to stereo-lithograph format, and imported into Meshmixer software (Autodesk, San Rafael, California). A 3.6 × 180 mm fibula rod model was virtually inserted to best fit the intramedullary canal of the fibula model and to a depth of 0 mm proud at the distal fibula. The location of the entry point in relationship to the fibular tip, and the distance between the rod and the lateral fibula cortex were measured. RESULTS: CT of 41 fibulae (23 male and 18 female patients) contributed to the three-dimensional fibula modeling. The entry point was 3.5 mm (SD 2.0) medial to (in mortise view) and 1.0 mm (SD 2.1) anterior to (in lateral view) the fibular tip. The fibula rod was inserted to a depth of 6.2 mm (SD 2.1) proximal to the fibula tip. The mean shortest distance of the rod to the outer cortex was 1.88 mm (SD 0.87). There was a breach of the posterolateral cortex in one patient. CONCLUSION: The guide pin entry site of fibula rod should be medial and anterior offset with reference to the fibula tip, in contrary to the distal tip as recommended in the manual. There is a chance of breaching the posterolateral cortex with rod entry.

A team beyond my team: establishing a national online neurodisability and community child health educational programme and network - a personal reflection.

The experience of establishing a virtual team and developing a national neurodisability and community online learning platform is discussed. The aim of the article is to advocate for the development of shared practice and communities of learning. Lessons learnt within this specialty forum may have broader relevance that could inform approaches to postgraduate teaching and virtual or online education. Regular access to national expert speakers offers trainees autonomy to meet their needs beyond local provision. Mapping objectives to the subspecialty level 3 curricula has been appreciated by both learners and speakers. Ease of speaker participation and the appeal of a national platform have revealed opportunities to provide a broad educational programme that goes beyond traditional topics. Being part of an educational forum stimulates wider discussion and makes engagement more accessible to a range of learning styles. The feedback responses indicate that the programme is valued by the learning community and provide insight into learners' needs during this time. The COVID-19 pandemic has reminded us of the importance of crucial themes underpinning our roles as healthcare professionals: communication, compassion, teamwork, sharing knowledge, responsiveness and professional development. The Neurodisability Community webinar development has been based on an ethos of coproduction using reciprocity and inclusion, recognising that trainees are well placed to address their educational needs. Allyship was essential to promote advocacy and network growth. The webinar programme was launched in Summer 2020, during a time when training was significantly disrupted. The programme was organised by trainees and supported generously by experts in the field.

Identification of a KPC Variant Conferring Resistance to Ceftazidime-Avibactam from ST11 Carbapenem-Resistant Klebsiella pneumoniae Strains.

A novel Klebsiella pneumoniae carbapenemase (KPC) variant, KPC-93, was identified in two Klebsiella pneumoniae clinical isolates from a patient from China treated with ceftazidime-avibactam. KPC-93 possessed a five-amino-acids insertion (Pro-Asn-Asn-Arg-Ala) between Ambler positions 267 and 268 in KPC-2. Cloning and expression of the blaKPC-93 gene in Escherichia coli, followed by determination of minimum inhibitory concentration (MIC) values and kinetic parameters, showed that KPC-93 exhibited increased resistance to ceftazidime-avibactam, but a drastic decrease in carbapenemase activity. Our data highlight that a KPC variant conferring resistance to ceftazidime-avibactam could be easily induced by ceftazidime-avibactam treatment and that actions are required to control dissemination of these determinants. IMPORTANCE Ceftazidime-avibactam (CZA) is a novel ß-lactam/ß-lactamase inhibitor combination with activity against serine ß-lactamases, including the Ambler class A enzyme KPC. However, during recent years, there have been increasing reports of emergence of new KPC variants that could confer resistance to CZA. This has limited its clinical application. Here, we reported a new KPC variant, KPC-93, that could confer CZA resistance. KPC-93 possessed a five-amino-acids insertion (Pro-Asn-Asn-Arg-Ala) between Ambler positions 267 and 268 in KPC-2. Our findings have revealed the potential risk of blaKPC gene mutations associated with CZA exposure over a short period of time.

Unveiling the evolution routes of TEM-type extended-spectrum ß-lactamases.

The TEM-1 ß-lactamase can only cleave penicillin and the first-generation cephalosporins but it has evolved to become active against second-, third- and fourth-generation drugs. Through sequence analysis of natural TEM variants and those created by mutagenesis experiments, we described two distinct evolution routes of TEM-1 that has generated over 220 enzyme variants. One began with the Gly238Ser alteration and the other originated with the Arg164Ser substitution. Further acquisition of mutations in the background of each of these two first-step mutants led to stepwise alteration in enzyme structure and hence activity, eventually producing a wide range of enzyme variants whose substrate specificities cover cephalosporins of all generations. Dissemination of strains producing TEM-1 variants generated from these two evolution routes underlies the markedly increased prevalence of bacterial resistance to ß-lactams in the past few decades. This study provides insights into the evolution of hydrolysing enzymes, in particular ß-lactamases.

The Effectiveness of Vocal Hygiene Education With Resonant Voice Therapy for School-Aged Children With Vocal Nodules.

OBJECTIVE: This study evaluated the effectiveness of vocal hygiene education with resonant voice therapy for school-aged children with vocal nodules. STUDY DESIGN: A pre-test/post-test control group design was employed. METHODS: Seventeen children aged between 6 and 9 years old with vocal nodules were randomly assigned to three groups: a treatment group, a placebo group and a control group. Children in the treatment group (n = 7) received six consecutive, weekly, one-hour sessions of vocal hygiene education with resonant voice therapy. Children in the placebo group (n = 5) received six consecutive, weekly, one-hour sessions on presentation skills training. Children in the control group (n = 5) did not receive any form of treatment. Subjective outcome measures included auditory-perceptual evaluation of overall dysphonia severity, the Pediatric Voice Handicap Index (pVHI) and the Children's Voice Handicap Index-10 (CVHI-10). Objective outcome measures included acoustic analysis of fundamental frequency, jitter, shimmer and noise-to-harmonic ratio. RESULTS AND CONCLUSIONS: Significant improvements in perceptual ratings of overall dysphonia severity levels and pVHI scores were found in the treatment group. No significant changes in acoustic measures and CVHI-10 scores were noted in any of the three groups. Interestingly, an improvement in perceptual overall dysphonia severity levels at post-evaluation was observed in the no treatment control group.

Total Synthesis of Mannopeptimycin ß via ß-Hydroxyenduracididine Ligation.

Nonribosomal peptide synthesis in bacteria has endowed cyclic peptides with fascinating structural complexity via incorporating nonproteinogenic amino acids. These bioactive cyclic peptides provide interesting structural motifs for exploring total synthesis and medicinal chemistry studies. Cyclic glycopeptide mannopeptimycins exhibit antibacterial activity against antibiotic-resistant Gram-positive pathogens and act as the lipid II binder to stop bacterial cell wall biosynthesis. Here, we report a strategy streamlining solution phase-solid phase synthesis and chemical ligation-mediated peptide cyclization for the total synthesis of mannopeptimycin ß.

Distinct interaction effects of warming and anthropogenic input on diatoms and dinoflagellates in an urbanized estuarine ecosystem.

Diatoms and dinoflagellates are two major bloom-forming phytoplankton groups in coastal ecosystems and their dominances will notably affect the marine ecosystems. By analyzing an 18-year monthly monitoring dataset (2000-2017) in the Pearl River Estuary (one of the most highly urbanized and populated estuarine in the world), we observe an increasing trend of the diatom to dinoflagellate ratio (Diatom/Dino). As revealed by multiple statistical models (generalized additive mixed model, random forest, and gradient boosting algorithms), both groups are positively correlated with temperature. Diatoms are positively correlated with nitrate and negatively correlated with ammonium while dinoflagellates show an opposite pattern. The Diatom/Dino trend is explained by an altered nutrient composition caused by a decadal increase in anthropogenic input, at which nitrate increased rapidly while ammonium and phosphate were relatively constant. Regarding the interaction of warming and nutrient dynamics, we observe an additive effect of warming and nitrate enrichment that promotes the increase in diatom cell density, while the dinoflagellate cell density only increases with warming when nutrients are depleted. Our models predict that the Diatom/Dino ratio will further increase with increasing anthropogenic input and global warming in subtropical estuarine ecosystems with nitrate as the dominant inorganic nitrogen; its ecological consequences are worthy of further investigation.

Screening for Obstructive Sleep Apnea in the Assessment of Coronary Risk.

There is increasing awareness that health screening may prevent some acute coronary events. Yet, obstructive sleep apnea (OSA) is seldom screened for and its relation with coronary risk markers is not well established. Consecutive adults (n = 696) enrolled in a cardiovascular health screening program were approached to determine the feasibility of incorporating OSA screening. Screening included questionnaires and a home-based sleep study. High-sensitivity C-reactive protein was the primary coronary risk marker, and other laboratory- and exercise treadmill-based markers were also reported. Two thirds of the participants (66%) agreed to undergo OSA screening and most (78%) successfully completed the sleep study. The prevalence of OSA (apnea-hypopnea index ≥15/hour) was 38.0%. The Berlin Questionnaire (53%) and Epworth Sleepiness Scale (26%) had low sensitivity in identifying OSA. After full adjustment for age, gender, body mass index, hypertension, and diabetes mellitus, OSA remained an independent predictor of serum levels of high-sensitivity C-reactive protein (relative mean difference 1.29, 95% CI 1.03 to 1.62; p = 0.025), triglyceride (relative mean difference 1.15, 95% CI 1.03 to 1.28; p = 0.014), and exercise time (mean difference -26.4 seconds; 95% CI -51.6 to -1.2; p = 0.04). The INTERHEART Risk Score analysis suggested more participants with (31%) than without (14%, p <0.001) OSA will develop future cardiovascular events. In conclusion, based on the acceptance for OSA screening, high prevalence of OSA and independent associations between OSA and coronary risk markers, incorporation of sleep studies into cardiovascular health screening programs appears feasible.

Validation of NoSAS score for screening of sleep-disordered breathing in a multiethnic Asian population.

PURPOSE: The NoSAS score was developed to identify subjects at high risk of sleep-disordered breathing (SDB). We aimed to validate the NoSAS score in a multiethnic Asian cohort and compare its performance to the STOP-Bang and Berlin questionnaires. METHODS: A sample of 242 subjects selected from a population-based cohort in Singapore completed home-based sleep testing with an Embletta device (type 3 monitor). All subjects were given the STOP-Bang and Berlin questionnaires for self-administration prior to the sleep study. The NoSAS score was subsequently calculated based on available demographic data and Berlin questionnaire responses. RESULTS: The prevalence of severe SDB, defined as an apnea-hypopnea index cutoff of ≥30 events/h, was 10.7%. The number of subjects who were classified as high risk by the NoSAS score and STOP-Bang and Berlin questionnaires were 76 (31.4%), 89 (36.8%), and 79 (32.6%), respectively. The sensitivity, specificity, and negative and positive predictive values of the NoSAS score to predict severe SDB were 69.2, 73.1, 95.2, and 23.7%, respectively. The STOP-Bang and Berlin questionnaires performed similarly to the NoSAS score, with area under the curve (AUC) values of all three questionnaires clustered around 0.682-0.748. Compared to the STOP-Bang (94.8%) and Berlin questionnaires (96.3%), the NoSAS score (95.2%) had equally high negative predictive value in ruling out severe SDB. CONCLUSIONS: The NoSAS score performed similarly to the STOP-Bang and Berlin questionnaires in a multiethnic Asian cohort. All three questionnaires had high negative predictive values in ruling out severe SDB and may have utility as screening tools.

Using the Berlin Questionnaire to Predict Obstructive Sleep Apnea in the General Population.

STUDY OBJECTIVES: The Berlin questionnaire is a self-administered questionnaire that was developed to identify subjects with obstructive sleep apnea (OSA) in primary care settings. This study evaluated the performance of the questionnaire to predict OSA in the general population. METHODS: A sample of 242 subjects in a population-based cohort completed a home-based sleep study with an Embletta device (type 3 monitor). Subjects completed the Berlin questionnaire on the evening just prior to the sleep study. The sleep studies were manually scored according to the 2012 American Academy of Sleep Medicine (AASM) criteria. RESULTS: The prevalence of moderate-to-severe and severe OSA defined as apnea-hypopnea index (AHI) of ≥ 15 and ≥ 30 was 28.1% and 10.7%, respectively. Seventy-nine subjects (32.6%) were classified as high risk according to the Berlin questionnaire. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of the questionnaire to predict an AHI ≥ 15 was 58.8%, 77.6%, 82.9%, and 50.6%, respectively. The area under the receiving operator characteristic (ROC) curve for moderate-to-severe OSA was 0.682. When used to predict an AHI ≥ 30, the sensitivity of the questionnaire increased to 76.9% with a small drop in specificity to 72.7%. The corresponding NPV, PPV, and area under the ROC curve of the questionnaire to predict severe OSA were 96.3%, 25.3%, and 0.748, respectively. CONCLUSIONS: The Berlin questionnaire may have utility in the general population setting as a screening tool for OSA in view of its good sensitivity and high NPV in ruling out severe OSA.

Predicting obstructive sleep apnea using the STOP-Bang questionnaire in the general population.

OBJECTIVE: The STOP-Bang questionnaire was developed as a quick and simple screening tool for obstructive sleep apnea (OSA) in preoperative clinics. We aimed to evaluate the validity of the STOP-Bang questionnaire to predict moderate-to-severe and severe OSA in the general population. METHODS: A sample of 242 subjects selected from a population-based cohort in Singapore completed home-based sleep testing with a type 3 monitor. Subjects were asked to complete the STOP questionnaire while body mass index (BMI), age, neck circumference, and sex were recorded. A score of ≥3 on the questionnaire indicated high risk of OSA. RESULTS: A total of 68 subjects (28.1%) and 26 subjects (10.7%) had an apnea-hypopnea index (AHI) of ≥15 and ≥30 events per hour, respectively. Of the subjects, 89 (36.8%) were classified as high risk based on the questionnaire. The sensitivity of a STOP-Bang score of ≥3 was 66.2% to detect AHI ≥15 and 69.2% to detect AHI ≥30. The specificities were 74.7% and 67.1%, respectively. The negative predictive values were 85% for moderate-to-severe OSA and 94.8% for severe OSA. The corresponding positive predictive values were 50.6% and 20.2%, respectively. Using BMI cutoffs of 30 and 27.5 for Asians compared to the original cutoff of 35 did not improve the questionnaire performance significantly. CONCLUSION: The STOP-Bang questionnaire can be used as a screening tool in the general population in view of its moderate sensitivity and high negative predictive value for subjects with moderate-to-severe and severe OSA. The cutoff of BMI >35 can be used in Asians, as lower BMI cutoffs did not improve questionnaire performance.

Use of Gradient Dilution to Detect and Correct Matrix Interferences in Inductively Coupled Plasma-Time-of-Flight Mass Spectrometry (ICP-TOFMS).

Our research group earlier used dispersion that occurs during flow injection to detect and reduce matrix interference in inductively coupled plasma-time-of-flight mass spectrometry (ICP-TOFMS). In the absence of a matrix interference, the ratio of signals from any two sample constituents should remain constant, independent of the dilution, over the course of a flow-injection transient. However, when an interferent is present, the signal ratio from different analytes will change with dilution, owing to the difference in severity of the interference on specific analytes. As a result, matrix interference can be recognized (flagged) by monitoring the signal ratios of two analytes over the course of a flow-injection transient; a ratio that changes over time indicates the presence of an interferent. The drawback of this earlier method was that dispersion, and therefore dilution, was somewhat element-specific, causing the ratios to wander even when no interference existed. Here, a gradient HPLC pump is used to overcome this drawback by creating a longer, better-controlled dilution. Under these conditions, variation in dispersion between elements is negligible and difficulties associated with it are reduced or eliminated. Further, when an interference exists, the optimal dilution factor to reduce the interference to an acceptable level can be found from the gradient-dilution curve as the point where the signal ratio between two elements becomes constant.

Prevalence of sleep-disordered breathing in a multiethnic Asian population in Singapore: A community-based study.

BACKGROUND AND OBJECTIVE: Limited data exist on the prevalence variation in sleep-disordered breathing (SDB) across different Asian ethnicities. This population study aimed to estimate the prevalence of SDB in Singapore, a multiethnic nation, and to quantify the prevalence variation among Chinese, Malays and Indians. METHODS: The Singapore Health Study 2012 was a cross-sectional population study conducted on adults aged 21-79 years. Among 2329 participants who completed baseline examination, a sample of 242 subjects completed home-based sleep testing with an Embletta device (type 3 monitor). Moderate-to-severe SDB, defined as an apnoea-hypopnoea index (AHI) of ≥15 events/h, was used to estimate prevalence. RESULTS: The weighted estimates of the population prevalence of moderate-to-severe SDB and sleep apnoea syndrome were 30.5% and 18.1%, respectively. Of subjects with AHI ≥15, 91.0% were previously undiagnosed. Moderate-to-severe SDB prevalence varied across the Chinese (32.1%), Malays (33.8%) and Indians (16.5%). The mean body mass index (BMI) was lowest in Chinese (23.3 kg/m(2) ) and highest among Malays (26.0 kg/m(2) ) and Indians (25.4 kg/m(2) ). Compared with Chinese, Indians had lower odds of moderate-to-severe SDB after adjustment for age, sex and BMI (odds ratio 0.82, 95% CI: 0.70-0.96, P = 0.02). CONCLUSION: Sleep-disordered breathing is prevalent but mostly undiagnosed among Asians in Singapore. There was a lower prevalence of SDB among Indians compared with Chinese that remained after adjustment for age, sex and BMI. Strategies are needed to optimize diagnosis and recognize ethnic differences in SDB prevalence.