Bacterial persisters are phenotypic variants that temporarily demonstrate an extraordinary tolerance toward antibiotics. Persisters have been linked to the recalcitrance of biofilm-related infections; hence, a complete understanding of their physiology can lead to improvement of therapeutic strategies for such infections. Mechanisms pertaining to persister formation are thought to be associated with stress response pathways triggered by intra- or extracellular stress factors. Unfortunately, studies demonstrating the effects of osmolyte- and/or pH-induced stresses on bacterial persistence are largely missing. To fill this knowledge gap within the field, we studied the effects of various osmolytes and pH conditions on Escherichia coli persistence with the use of phenotype microarrays and antibiotic tolerance assays. Although we found that a number of chemicals and pH environments, including urea, sodium nitrite, and acidic pH, significantly reduced persister formation in E. coli compared to no-osmolyte/no-buffer controls, this reduction in persister levels was less pronounced in late-stationary-phase cultures. Our results further demonstrated a positive correlation between cell growth and persister formation, which challenges the general notion in the field that slow-growing cultures have more persister cells than fast-growing cultures.

KBP-7072 is a novel third-generation tetracycline (aminomethylcycline) antibacterial that overcomes common efflux and ribosomal protection resistance mechanisms that cause resistance in older-generation tetracyclines. KBP-7072 completed phase 1 clinical development studies for safety, tolerability, and pharmacokinetics (ClinicalTrials.gov identifier NCT02454361) and multiple ascending doses in healthy subjects (ClinicalTrials.gov identifier NCT02654626) in December 2015. Both oral and intravenous formulations of KBP-7072 are being developed. In this study, we evaluated the in vitro activities of KBP-7072 and comparator agents by CLSI document M07 (2018) broth microdilution against 531 recent geographically diverse and/or molecularly characterized Acinetobacter baumannii-A. calcoaceticus species complex (A. baumannii) isolates from the United States, Europe, Asia-Pacific (excluding China), and Latin America. A. baumannii isolates included carbapenem-resistant, colistin-resistant, tetracycline-resistant, and extended-spectrum-β-lactamase (ESBL)- and metallo-β-lactamase (MBL)-producing isolates. Overall, KBP-7072 (MIC_50/90, 0.25/1 mg/liter) was comparable in activity to colistin (92.8%/92.8% susceptible [S] [CLSI/EUCAST]) against A. baumannii isolates, inhibiting 99.2% of isolates at ≤2 mg/liter and 97.6% of isolates at ≤1 mg/liter. KBP-7072 was equally active against A. baumannii isolates, including carbapenem-resistant, colistin-resistant, and tetracycline-resistant isolates, regardless of geographic location, and maintained activity against ESBL- and MBL-producing isolates. KBP-7072 outperformed comparator agents, including ceftazidime (40.3% S [CLSI]), gentamicin (48.2%/48.2% S [CLSI/EUCAST]), levofloxacin (39.5%/37.9% S [CLSI/EUCAST]), meropenem (42.0%/42.0% S [CLSI/EUCAST]), piperacillin-tazobactam (33.3% S [CLSI]), and all tetracycline-class comparator agents, which include doxycycline (67.3% S [CLSI]), minocycline (73.8% S [CLSI]), tetracycline (37.2% S [CLSI]), and tigecycline (79.5% inhibited by ≤2 mg/liter). The potent in vitro activity of KBP-7072 against recent geographically diverse, molecularly characterized, and drug-resistant A. baumannii isolates supports continued clinical development for the treatment of serious infections, including those caused by A. baumannii.

Nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP), is increasingly associated with multidrug-resistant Gram-negative pathogens. This study describes the in vitro activity of ceftazidime-avibactam, ceftazidime, and relevant comparator agents against bacterial pathogens isolated from patients with NP, including VAP, enrolled in a ceftazidime-avibactam phase 3 trial. Gram-positive pathogens were included if coisolated with a Gram-negative pathogen. In vitro susceptibility was determined at a central laboratory using Clinical and Laboratory Standards Institute broth microdilution methods. Of 817 randomized patients, 457 (55.9%) had ≥1 Gram-negative bacterial pathogen(s) isolated at baseline, and 149 (18.2%) had ≥1 Gram-positive pathogen(s) coisolated. The most common isolated pathogens were Klebsiella pneumoniae (18.8%), Pseudomonas aeruginosa (15.8%), and Staphylococcus aureus (11.5%). Ceftazidime-avibactam was highly active in vitro against 370 isolates of Enterobacteriaceae, with 98.6% susceptible (MIC₉₀, 0.5 μg/ml) compared with 73.2% susceptible for ceftazidime (MIC₉₀, >64 μg/ml). The percent susceptibility values for ceftazidime-avibactam and ceftazidime against 129 P. aeruginosa isolates were 88.4% and 72.9% (MIC₉₀ values of 16 μg/ml and 64 μg/ml), respectively. Among ceftazidime-nonsusceptible Gram-negative isolates, ceftazidime-avibactam percent susceptibility values were 94.9% for 99 Enterobacteriaceae and 60.0% for 35 P. aeruginosa. MIC₉₀ values for linezolid and vancomycin (permitted per protocol for Gram-positive coverage) were within their respective MIC susceptibility breakpoints against the Gram-positive pathogens isolated. This analysis demonstrates that ceftazidime-avibactam was active in vitro against the majority of Enterobacteriaceae and P. aeruginosa isolates from patients with NP, including VAP, in a phase 3 trial. (This study has been registered at ClinicalTrials.gov under identifier NCT01808092.)

Lactoferrin (LF) is a multifunctional milk protein with antimicrobial activity against a range of pathogens. While numerous studies report that LF is active against fungi, there are considerable differences in the level of antifungal activity and the capacity of LF to interact with other drugs. Here we undertook a comprehensive evaluation of the antifungal spectrum of activity of three defined sources of LF across 22 yeast and 24 mold species and assessed its interactions with six widely used antifungal drugs. LF was broadly and consistently active against all yeast species tested (MICs, 8 to 64 μg/ml), with the extent of activity being strongly affected by iron saturation. LF was synergistic with amphotericin B (AMB) against 19 out of 22 yeast species tested, and synergy was unaffected by iron saturation but was affected by the extent of LF digestion. LF-AMB combination therapy significantly prolonged the survival of Galleria mellonella wax moth larvae infected with Candida albicans or Cryptococcus neoformans and decreased the fungal burden 12- to 25-fold. Evidence that LF directly interacts with the fungal cell surface was seen via scanning electron microscopy, which showed pore formation, hyphal thinning, and major cell collapse in response to LF-AMB synergy. Important virulence mechanisms were disrupted by LF-AMB treatment, which significantly prevented biofilms in C. albicans and C. glabrata, inhibited hyphal development in C. albicans, and reduced cell and capsule size and phenotypic diversity in Cryptococcus. Our results demonstrate the potential of LF-AMB as an antifungal treatment that is broadly synergistic against important yeast pathogens, with the synergy being attributed to the presence of one or more LF peptides.

Balamuthia mandrillaris is an under-reported, pathogenic free-living amoeba that causes Balamuthia amoebic encephalitis (BAE) and cutaneous skin infections. Although cutaneous infections are not typically lethal, BAE with or without cutaneous involvement is usually fatal. This is due to the lack of drugs that are both efficacious and can cross the blood-brain barrier. We aimed to discover new leads for drug discovery by screening the open-source Medicines for Malaria Venture (MMV) Malaria Box and MMV Pathogen Box, with 800 compounds total. From an initial single point screen at 1 and 10 μM, we identified 54 hits that significantly inhibited the growth of B. mandrillaris in vitro. Hits were reconfirmed in quantitative dose-response assays and 23 compounds (42.6%) were confirmed with activity greater than miltefosine, the current standard of care.

Scabies is a frequent cutaneous infection caused by the mite Sarcoptes scabiei in a large number of mammals, including humans. As the resistance of S. scabiei against several chemical acaricides has been previously documented, the establishment of alternative and effective control molecules is required. In this study, the potential acaricidal activity of beauvericin was assessed against different life stages of S. scabiei var. suis and in comparison with dimpylate and ivermectin, two commercially available molecules used for the treatment of S. scabiei infection in animals and/or humans. The toxicity of beauvericin against cultured human fibroblast skin cells was evaluated using an MTT proliferation assay. In our in vitro model, developmental stages of S. scabiei were placed in petri dishes filled with Columbia agar supplemented with pig serum and different concentrations of the drugs. Cell sensitivity assays demonstrated low toxicity of beauvericin against primary human fibroblast skin cells. At 0.5 and 5 mM, beauvericin showed higher activity against adults and eggs of S. scabiei compared to dimpylate and ivermectin. These results revealed that the use of beauvericin is promising and might be considered for the treatment of S. scabiei infection.

Enterococcus faecium strains are commonly resistant to vancomycin and β-lactams. In addition, E. faecium often causes biofilm-associated infections and these infections are difficult to treat. In this context, we investigated the activity of dosing regimens using daptomycin (DAP) (8, 10, 12, and 14 mg/kg of body weight/day) alone and in combination with ceftaroline (CPT), ampicillin (AMP), ertapenem (ERT), and rifampin (RIF) against 2 clinical strains of biofilm-producing vancomycin-resistant Enterococcus faecium (VREfm), namely, strains S447 and HOU503, in an in vitro biofilm model. HOU503 harbors common LiaS and LiaR substitutions, whereas S447 lacks mutations associated with the LiaFSR pathway. MIC results demonstrated that both strains were susceptible to DAP and resistant to CPT, AMP, ERT, and RIF. The 168-h pharmacokinetic/pharmacodynamic (PK/PD) CDC biofilm reactor models (simulating human antibiotic exposures) were used with titanium and polyurethane coupons to evaluate the efficacy of antibiotic combinations. DAP 12 and 14 achieved bactericidal activity against S447 but lacked such effect against HOU503. Addition of ERT and RIF enhanced DAP activity, allowing DAP 8 and 10 plus ERT or RIF to produce bactericidal activity against both strains at 168 h. While DAP 8 and 10 plus CPT improved killing, they did not reach bactericidal reduction against S447. Combination of AMP, CPT, ERT, or RIF resulted in enhanced and bactericidal activity for DAP against HOU503 at 168 h. Our data provide further support for the use of combinations of DAP with AMP, ERT, CPT, and RIF in infections caused by biofilm producing VREfm. Further research involving DAP combinations against biofilm-producing enterococci is warranted.

Staphylococcus aureus biofilms are a significant problem in health care settings, partly due to the presence of a nondividing, antibiotic-tolerant subpopulation. Here we evaluated treatment of S. aureus UAMS-1 biofilms with HT61, a quinoline derivative shown to be effective against nondividing Staphylococcus spp. HT61 was effective at reducing biofilm viability and was associated with increased expression of cell wall stress and division proteins, confirming its potential as a treatment for S. aureus biofilm infections.

The new complexes Zn(ITZ)₂Cl₂ (1) and Zn(ITZ)₂(OH)₂ (2) were synthetized by a reaction of itraconazole with their respective zinc salts under reflux. These Zn-ITZ complexes were characterized by elemental analyses, molar conductivity, mass spectrometry, ¹H and ¹³C{¹H} nuclear magnetic resonance, and UV-vis and infrared spectroscopies. The antiparasitic and antifungal activity of Zn-ITZ complexes was evaluated against three protozoans of medical importance, namely, Leishmania amazonensis, Trypanosoma cruzi, and Toxoplasma gondii, and two fungi, namely, Sporothrix brasiliensis and Sporothrix schenckii. The Zn-ITZ complexes exhibited a broad spectrum of action, with antiparasitic and antifungal activity in low concentrations. The strategy of combining zinc with ITZ was efficient to enhance ITZ activity since Zn-ITZ-complexes were more active than the azole alone. This study opens perspectives for future applications of these Zn-ITZ complexes in the treatment of parasitic diseases and sporotrichosis.

Omadacycline is an aminomethylcycline antibiotic with in vitro activity against pathogens causing community-acquired bacterial pneumonia (CABP). This study investigated the activity of omadacycline against Legionella pneumophila strains isolated between 1995 and 2014 from nosocomial or community-acquired respiratory infections. Omadacycline exhibited extracellular activity similar to comparator antibiotics; intracellular penetrance was found by day 3 of omadacycline exposure. These results support the utility of omadacycline as an effective antibiotic for the treatment of CABP caused by L. pneumophila.

Cefiderocol inhibited 97.5% of 478 Gram-negative isolates from cancer patients at ≤4 mg/liter. It had potent activity against extended-spectrum β-lactamase-positive Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae (CRE), and nonfermenting Gram-negative bacilli, including Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter species isolates. Amikacin, ceftazidime-avibactam, and meropenem had appreciable activity against non-CRE Enterobacteriaceae. No comparators were active against multidrug-resistant P. aeruginosa isolates. Only trimethoprim-sulfamethoxazole had appreciable activity against S. maltophilia isolates. Overall, cefiderocol was associated with the lowest level of resistance.

Manogepix is a broad-spectrum antifungal agent that inhibits glycosylphosphatidylinositol (GPI) anchor biosynthesis. Using whole-genome sequencing, we characterized two efflux-mediated mechanisms in the fungal pathogens Candida albicans and Candida parapsilosis that resulted in decreased manogepix susceptibility. In C. albicans, a gain-of-function mutation in the transcription factor gene ZCF29 activated expression of ATP-binding cassette transporter genes CDR11 and SNQ2. In C. parapsilosis, a mitochondrial deletion activated expression of the major facilitator superfamily transporter gene MDR1.

Nine hundred Haemophilus influenzae clinical isolates from 83 U.S. and European medical centers were tested for susceptibility by reference broth microdilution methods against ceftolozane-tazobactam and comparators. Results were stratified by β-lactamase production and infection type. Overall, ceftolozane-tazobactam MIC_50/90 values were 0.12/0.25 mg/liter, and 99.0% of isolates were inhibited at the susceptible breakpoint of ≤0.5 mg/liter; the highest MIC value was only 2 mg/liter. Our results support using ceftolozane-tazobactam to treat H. influenzae infections.

Mismatch repair (MMR)–deficient tumors exhibit proteome-wide protein instability and aggregation.

It is well established that African Americans exhibit higher incidence, higher mortality, and more aggressive forms of some cancers, including those of breast, prostate, colon, stomach, and cervix. Here we examine the ancestral haplotype of the TRPV6 calcium channel as a putative genomic factor in this racial divide. The minor (ancestral) allele frequency is 60% in people of African ancestry, but between 1% and 11% in all other populations. Research on TRPV6 structure/function, its association with specific cancers, and the evolutionary-ecological conditions that impacted selection of its haplotypes are synthesized to provide evidence for TRPV6 as a germline susceptibility locus in cancer. Recently elucidated mechanisms of TRPV6 channel deactivation are discussed in relation to the location of the allele favored in selection, suggesting a reduced capacity to inactivate the channel in those who have the ancestral haplotype. This could result in an excessively high cellular Ca²⁺, which has been implicated in cancer, for those in settings where calcium intake is far higher than in their ancestral environment. A recent report associating increasing calcium intake with a pattern of increase in aggressive prostate cancer in African-American but not European-American men may be related. If TRPV6 is found to be associated with cancer, further research would be warranted to improve risk assessment and examine interventions with the aim of improving cancer outcomes for people of African ancestry.

BACKGROUND AND PURPOSE:

Diffuse intrinsic pontine glioma is a lethal childhood brain cancer with dismal prognosis and MR imaging is the primary methodology used for diagnosis and monitoring. Our aim was to determine whether advanced diffusion, perfusion, and permeability MR imaging metrics predict survival and pseudoprogression in children with newly diagnosed diffuse intrinsic pontine glioma.

BACKGROUND AND PURPOSE:

After endovascular coiling of intracranial aneurysms, round dark parenchymal lesions believed to be particulate metal are sometimes encountered in MR imaging studies of the brain. We used SWI to assess the frequency of such occurrences, in addition to exploring likely causes and clinical implications.

BACKGROUND AND PURPOSE:

Computed tomography angiography offers a non-invasive alternative to DSA for the assessment of cerebral vasospasm following subarachnoid hemorrhage but there is limited evidence regarding its reliability. Our aim was to perform a systematic review (Part I) and to assess (Part II) the inter- and intraobserver reliability of CTA in the diagnosis of cerebral vasospasm.

BACKGROUND AND PURPOSE:

Anoxic brain injury is a result of prolonged hypoxia. We sought to describe the nonquantitative arterial spin-labeling perfusion imaging patterns of anoxic brain injury, characterize the relationship of arterial spin-labeling and DWI, and evaluate the normalized diffusion-to-perfusion ratio to differentiate patients with anoxic brain injury from healthy controls.

BACKGROUND AND PURPOSE:

Accurate differentiation between glioblastoma and solitary brain metastasis is of vital importance clinically. This study aimed to investigate the potential value of the inflow-based vascular-space-occupancy MR imaging technique, which has no need for an exogenous contrast agent, in differentiating glioblastoma and solitary brain metastasis and to compare it with DSC MR imaging.

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Julia Ebner infiltrated the hidden forums that extremists use. Her experiences lay bare how they hijack social media and video games to spread hate – and how to beat them

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