Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

課室．政治．香港的未來 = Classroom, politics and Hong Kong’s future

公開研討會由嶺南大學文化研究系許寶強教授主持，討論「課室．政治．香港的未來」，先由三位講者就不同講題發言，然後由劉慧思小姐作出回應及評論，再互相進行討論，及後並由聽眾提問或發表意見。研討會試從演講及討論中，思考香港的教育正培養怎樣的政治的主人翁，而香港的政治又對課室和學校的生活有什麼的影響。 練美兒教授先分享她在課室裡的微觀社會學研究，從而拆解課堂的運作，剖析課室裡人與人的交往及師生合奏的三部曲，展現兩種學生不同的態度。吳詠雪教授就講題「香港教師的身份在學校的過程中是如何被打造的？」發言，分享她的教學經驗，看看教師進入教師專業的經歷、在教學中的適應、及其成長過程。莫昭如先生則分享他對創意教學、通識教育的看法，從宏觀的角度去看香港的教育制度。 相關文章 : 香港教師的身份在學校的過程中是如何被打造的？ / 吳詠雪 講稿 / 莫昭如 講稿 / 練美兒 講稿 / 劉慧

The Proteome of Community Living Candida albicans Is Differentially Modulated by the Morphologic and Structural Features of the Bacterial Cohabitants

Candida albicans is a commensal polymorphic and opportunistic fungus, which usually resides as a small community in the oral cavities of a majority of humans. The latter eco-system presents this yeast varied opportunities for mutualistic interactions with other cohabitant oral bacteria, that synergizes its persistence and pathogenicity. Collectively, these communities live within complex plaque biofilms which may adversely affect the oral health and increase the proclivity for oral candidiasis. The proteome of such oral biofilms with myriad interkingdom interactions are largely underexplored. Herein, we employed limma differential expression analysis, and cluster analysis to explore the proteomic interactions of C. albicans biofilms with nine different common oral bacterial species, Aggregatibacter actinomycetemcomitans, Actinomyces naeslundii, Fusobacterium nucleatum, Enterococcus faecalis, Porphyromonas gingivalis, Streptococcus mutants, Streptococcus sanguinis, Streptococcus mitis, and Streptococcus sobrinus. Interestingly, upon exposure of C. albicans biofilms to the foregoing heat-killed bacteria, the proteomes of the fungus associated with cellular respiration, translation, oxidoreductase activity, and ligase activity were significantly altered. Subsequent differential expression and cluster analysis revealed the subtle, yet significant alterations in the C. albicans proteome, particularly on exposure to bacteria with dissimilar cell morphologies, and Gram staining characteristics

Compliance of healthcare workers in a psychiatric inpatient ward to infection control practices during the COVID-19 pandemic: a participant observation study supplemented with a self-reported survey

Abstract Background As an emerging infectious disease with a heterogenous and uncertain transmission pattern, coronavirus disease 2019 (COVID-19) has created a catastrophe in healthcare-associated infections (HAIs) and posed a significant challenge to infection control practices (ICPs) in healthcare settings. While the unique characteristics of psychiatric patients and clinical settings may make the implementation of ICPs difficult, evidence is lacking for compliance with ICPs among healthcare workers (HCWs) in a psychiatric setting during the COVID-19 pandemic. Methods A cross-sectional multi-method study based on participant unobtrusive observation coupled with the completion of a self-administered ICP survey was conducted to assess compliance with ICPs among HCWs in a psychiatric inpatient ward in a regional hospital. An online checklist, called eRub, was used to record the performance of HCWs in hand hygiene (HH) and other essential ICPs. Furthermore, a well-validated questionnaire (i.e., Compliance with Standard Precautions Scale, CSPS) was used to collect the participants’ self-reported ICP compliance for later comparison. Results A total of 2,670 ICP opportunities were observed from January to April 2020. The overall compliance rate was 42.6%. HCWs exhibited satisfactory compliance to the wearing of mask (91.2%) and the handling of clinical waste (87.5%); suboptimal compliance to the handling of sharp objects (67.7%) and linen (72.7%); and poor compliance to HH (3.3%), use of gloves (40.9%), use of personal protective equipment (20%), and disinfection of used surface/area (0.4%). The compliance rates of the nurses and support staff to HH were significantly different (χ2 = 123.25, p < 0.001). In the self-reported survey, the overall compliance rate for ICPs was 64.6%. Conclusion The compliance of HCWs in a psychiatric inpatient ward to ICPs during the COVID-19 pandemic ranged from poor to suboptimal. This result was alarming. Revisions of current ICP guidelines and policies that specifically target barriers in psychiatric settings will be necessary

Actin-related protein 2/3 complex subunit 2-enriched extracellular vesicles drive liver cancer metastasis

Background: Extracellular vesicles (EVs) play pivotal roles in tumor growth, cancer metastasis and angiogenesis. Here, we aimed to identify proteins that contribute to the functionality of EVs derived from metastatic hepatocellular carcinoma (HCC) cells. Methods: Proteins of EVs derived from metastatic HCC cells and normal liver cells were analyzed by mass spectrometry. Proteomic profiling identified actin-related protein 2/3 complex subunit 2 (ARPC2) to be highly expressed in EVs of metastatic HCC cells. The expression of ARPC2 in EVs and HCC tissues was examined using immunoblotting and TCGA database, respectively. The functional roles of EV-ARPC2 were investigated by knockout approach and various in vitro and in vivo assays. Results: ARPC2 was highly expressed in EVs of metastatic cells but barely detected in non-metastatic HCC cells and normal liver cells. Immunogold labeling showed the presence of APRC2 on the surface of EVs. Analysis of TCGA database of liver cancer revealed ARPC2 overexpression was correlated with poor prognosis of patients. ARPC2 was knockout in metastatic HCC cells. EVs derived from knockout cells displayed compromised activity in enhancing cell growth, motility and metastasis compared to EVs of control cells. Pimozide, an inhibitor of APRC2, also inhibited the promoting effect of EVs of metastatic cells in lung colonization of tumor cells in mice. Conclusion: This study reveals previously unreported expression and function of ARPC2 in EVs. EVs with highly expressed ARPC2 enhance cancer cell growth and metastasis. ARPC2 may provide a prospective target for the novel treatment of HCC patients.The work was supported by National Natural Science Foundation of China (NSFC) General Program (Grant number: 81872340 and 82072626)

Tailorable Remote Unmanned Combat Craft

U.S. military and civilian vessels are critically vulnerable to asymmetric threats in littoral environments. Common asymmetric weapons such as Anti-Ship Cruise Missiles (ASCM), Low Slow Flying (LSF) aircraft and Fast Attack Craft (FAC) / Fast Inshore Attack Craft (FIAC) threaten U.S. strategic goals and can produce unacceptable losses of men and material. The SEA-18B team presents an operational concept for a family of Unmanned Surface Vessels USV) capable of defending ships from asymmetric swarm attacks. This USV, the Tailorable Remote Unmanned Combat Craft (TRUCC), can operate in concert with the next generation of capital surface vessels to combat this critical threat with maximum efficiency. Critical performance criteria of the TRUCC family were determined through agent-based simulation of a Straits of Hormuz Design Reference Mission. Additional models addressed ship synthesis and operational availability. A Technology and Capability Roadmap outlines areas of interest for investment and development of the next-generation USV. Interim technology and capability milestones in the Roadmap facilitate incremental USV operational capabilities for missions such as logistics, decoy operations and Mine Warfare. The TRUCC operational concept fills a critical vulnerability gap. Its employment will reduce combat risk to our most valuable maritime assets: our ships and our Sailors.http://archive.org/details/tailorableremote1094515434Approved for public release; distribution is unlimited

Hypoglycemic effects of dracorhodin and dragon blood crude extract from Daemonorops draco

Abstract Background Dragon blood is a red fruit resin from the palm tree Daemonorops draco and is a herbal ingredient used in the traditional Chinese medicine, “Jinchuang Ointment,” which is used to treat non-healing diabetic wounds. According to the Taiwan Herbal Pharmacopeia, the dracorhodin content in dragon blood should exceed 1.0%. Results Our findings indicate that dracorhodin and dragon blood crude extracts can stimulate glucose uptake in mouse muscle cells (C2C12) and primary rat aortic smooth muscle cells (RSMC). Dracorhodin is not the only active compound in dragon blood crude extracts from D. draco. Next, we orally administered crude dragon blood extracts to male B6 mice. The experimental group displayed a decreasing trend in fasting blood glucose levels from the second to tenth week. In summary, crude extracts of dragon blood from D. draco demonstrated in vivo hypoglycemic effects in B6 male mice. Conclusions We provide a scientific basis “Jinchuang ointment” in treating non-healing wounds in patients with diabetes

The liver-gut microbiota axis modulates hepatotoxicity of tacrine in the rat

10.1002/hep.29327HEPATOLOGY671282-29