Sibylle Béchet
Apr 8, 2020; 40:3104-3118
Neurobiology of Disease

Amanda Avona
May 29, 2019; 39:4323-4331
Systems/Circuits

Xiao-Jing Wang
Oct 15, 1996; 16:6402-6413
Articles

In what could be a trial run for more of the same, Red Hat last week held a first-ever virtual technical summit to spread the word about its latest cloud tech offerings. CEO Paul Cormier welcomed online viewers to the conference, which attracted more than 80,000 virtual attendees. The company made several key announcements during the online gathering and highlighted customer innovations.

Krabbe's disease is an infantile neurodegenerative disease, which is affected by mutations in the lysosomal enzyme galactocerebrosidase, leading to the accumulation of its metabolite psychosine. We have shown previously that the S1P receptor agonist fingolimod (FTY720) attenuates psychosine-induced glial cell death and demyelination both in vitro and ex vivo models. These data, together with a lack of therapies for Krabbe's disease, prompted the current preclinical study examining the effects of fingolimod in twitcher mice, a murine model of Krabbe's disease. Twitcher mice, both male and female, carrying a natural mutation in the galc gene were given fingolimod via drinking water (1 mg/kg/d). The direct impact of fingolimod administration was assessed via histochemical and biochemical analysis using markers of myelin, astrocytes, microglia, neurons, globoid cells, and immune cells. The effects of fingolimod on twitching behavior and life span were also demonstrated. Our results show that treatment of twitcher mice with fingolimod significantly rescued myelin levels compared with vehicle-treated animals and also regulated astrocyte and microglial reactivity. Furthermore, nonphosphorylated neurofilament levels were decreased, indicating neuroprotective and neurorestorative processes. These protective effects of fingolimod on twitcher mice brain pathology was reflected by an increased life span of fingolimod-treated twitcher mice. These in vivo findings corroborate initial in vitro studies and highlight the potential use of S1P receptors as drug targets for treatment of Krabbe's disease.

SIGNIFICANCE STATEMENT This study demonstrates that the administration of the therapy known as fingolimod in a mouse model of Krabbe's disease (namely, the twitcher mouse model) significantly rescues myelin levels. Further, the drug fingolimod also regulates the reactivity of glial cells, astrocytes and microglia, in this mouse model. These protective effects of fingolimod result in an increased life span of twitcher mice.

Although the etiology of schizophrenia is still unknown, it is accepted to be a neurodevelopmental disorder that results from the interaction of genetic vulnerabilities and environmental insults. Although schizophrenia's pathophysiology is still unclear, postmortem studies point toward a dysfunction of cortical interneurons as a central element. It has been suggested that alterations in parvalbumin-positive interneurons in schizophrenia are the consequence of a deficient signaling through NMDARs. Animal studies demonstrated that early postnatal ablation of the NMDAR in corticolimbic interneurons induces neurobiochemical, physiological, behavioral, and epidemiological phenotypes related to schizophrenia. Notably, the behavioral abnormalities emerge only after animals complete their maturation during adolescence and are absent if the NMDAR is deleted during adulthood. This suggests that interneuron dysfunction must interact with development to impact on behavior. Here, we assess in vivo how an early NMDAR ablation in corticolimbic interneurons impacts on mPFC and ventral hippocampus functional connectivity before and after adolescence. In juvenile male mice, NMDAR ablation results in several pathophysiological traits, including increased cortical activity and decreased entrainment to local gamma and distal hippocampal theta rhythms. In addition, adult male KO mice showed reduced ventral hippocampus-mPFC-evoked potentials and an augmented low-frequency stimulation LTD of the pathway, suggesting that there is a functional disconnection between both structures in adult KO mice. Our results demonstrate that early genetic abnormalities in interneurons can interact with postnatal development during adolescence, triggering pathophysiological mechanisms related to schizophrenia that exceed those caused by NMDAR interneuron hypofunction alone.

SIGNIFICANCE STATEMENT NMDAR hypofunction in cortical interneurons has been linked to schizophrenia pathophysiology. How a dysfunction of GABAergic cortical interneurons interacts with maturation during adolescence has not been clarified yet. Here, we demonstrate in vivo that early postnatal ablation of the NMDAR in corticolimbic interneurons results in an overactive but desynchronized PFC before adolescence. Final postnatal maturation during this stage outspreads the impact of the genetic manipulation toward a functional disconnection of the ventral hippocampal-prefrontal pathway, probably as a consequence of an exacerbated propensity toward hippocampal-evoked depotentiation plasticity. Our results demonstrate a complex interaction between genetic and developmental factors affecting cortical interneurons and PFC function.

The detection and segmentation of meaningful figures from their background is one of the primary functions of vision. While work in nonhuman primates has implicated early visual mechanisms in this figure–ground modulation, neuroimaging in humans has instead largely ascribed the processing of figures and objects to higher stages of the visual hierarchy. Here, we used high-field fMRI at 7 Tesla to measure BOLD responses to task-irrelevant orientation-defined figures in human early visual cortex (N = 6, four females). We used a novel population receptive field mapping-based approach to resolve the spatial profiles of two constituent mechanisms of figure–ground modulation: a local boundary response, and a further enhancement spanning the full extent of the figure region that is driven by global differences in features. Reconstructing the distinct spatial profiles of these effects reveals that figure enhancement modulates responses in human early visual cortex in a manner consistent with a mechanism of automatic, contextually driven feedback from higher visual areas.

SIGNIFICANCE STATEMENT A core function of the visual system is to parse complex 2D input into meaningful figures. We do so constantly and seamlessly, both by processing information about visible edges and by analyzing large-scale differences between figure and background. While influential neurophysiology work has characterized an intriguing mechanism that enhances V1 responses to perceptual figures, we have a poor understanding of how the early visual system contributes to figure–ground processing in humans. Here, we use advanced computational analysis methods and high-field human fMRI data to resolve the distinct spatial profiles of local edge and global figure enhancement in the early visual system (V1 and LGN); the latter is distinct and consistent with a mechanism of automatic, stimulus-driven feedback from higher-level visual areas.

Endogenous neuropeptide Y (NPY) and corticotrophin-releasing factor (CRF) modulate the responses of the basolateral amygdala (BLA) to stress and are associated with the development of stress resilience and vulnerability, respectively. We characterized persistent effects of repeated NPY and CRF treatment on the structure and function of BLA principal neurons in a novel organotypic slice culture (OTC) model of male rat BLA, and examined the contributions of specific NPY receptor subtypes to these neural and behavioral effects. In BLA principal neurons within the OTCs, repeated NPY treatment caused persistent attenuation of excitatory input and induced dendritic hypotrophy via Y₅ receptor activation; conversely, CRF increased excitatory input and induced hypertrophy of BLA principal neurons. Repeated treatment of OTCs with NPY followed by an identical treatment with CRF, or vice versa, inhibited or reversed all structural changes in OTCs. These structural responses to NPY or CRF required calcineurin or CaMKII, respectively. Finally, repeated intra-BLA injections of NPY or a Y₅ receptor agonist increased social interaction, a validated behavior for anxiety, and recapitulated structural changes in BLA neurons seen in OTCs, while a Y₅ receptor antagonist prevented NPY's effects both on behavior and on structure. These results implicate the Y₅ receptor in the long-term, anxiolytic-like effects of NPY in the BLA, consistent with an intrinsic role in stress buffering, and highlight a remarkable mechanism by which BLA neurons may adapt to different levels of stress. Moreover, BLA OTCs offer a robust model to study mechanisms associated with resilience and vulnerability to stress in BLA.

SIGNIFICANCE STATEMENT Within the basolateral amygdala (BLA), neuropeptide Y (NPY) is associated with buffering the neural stress response induced by corticotropin releasing factor, and promoting stress resilience. We used a novel organotypic slice culture model of BLA, complemented with in vivo studies, to examine the cellular mechanisms associated with the actions of NPY. In organotypic slice cultures, repeated NPY treatment reduces the complexity of the dendritic extent of anxiogenic BLA principal neurons, making them less excitable. NPY, via activation of Y5 receptors, additionally inhibits and reverses the increases in dendritic extent and excitability induced by the stress hormone, corticotropin releasing factor. This NPY-mediated neuroplasticity indicates that resilience or vulnerability to stress may thus involve neuropeptide-mediated dendritic remodeling in BLA principal neurons.

Synaptic dysfunction provoking dysregulated cortical neural circuits is currently hypothesized as a key pathophysiological process underlying clinical manifestations in Alzheimer's disease and related neurodegenerative tauopathies. Here, we conducted PET along with postmortem assays to investigate time course changes of excitatory and inhibitory synaptic constituents in an rTg4510 mouse model of tauopathy, which develops tau pathologies leading to noticeable brain atrophy at 5-6 months of age. Both male and female mice were analyzed in this study. We observed that radiosignals derived from [¹¹C]flumazenil, a tracer for benzodiazepine receptor, in rTg4510 mice were significantly lower than the levels in nontransgenic littermates at 2-3 months of age. In contrast, retentions of (E)-[¹¹C]ABP688, a tracer for mGluR5, were unaltered relative to controls at 2 months of age but then gradually declined with aging in parallel with progressive brain atrophy. Biochemical and immunohistochemical assessment of postmortem brain tissues demonstrated that inhibitory, but not excitatory, synaptic constituents selectively diminished without overt loss of somas of GABAergic interneurons in the neocortex and hippocampus of rTg4510 mice at 2 months of age, which was concurrent with enhanced immunoreactivity of cFos, a well-characterized immediate early gene, suggesting that impaired inhibitory neurotransmission may cause hyperexcitability of cortical circuits. Our findings indicate that tau-induced disruption of the inhibitory synapse may be a critical trigger of progressive neurodegeneration, resulting in massive neuronal loss, and PET assessments of inhibitory versus excitatory synapses potentially offer in vivo indices for hyperexcitability and excitotoxicity early in the etiologic pathway of neurodegenerative tauopathies.

SIGNIFICANCE STATEMENT In this study, we examined the in vivo status of excitatory and inhibitory synapses in the brain of the rTg4510 tauopathy mouse model by PET imaging with (E)-[¹¹C]ABP688 and [¹¹C]flumazenil, respectively. We identified inhibitory synapse as being significantly dysregulated before brain atrophy at 2 months of age, while excitatory synapse stayed relatively intact at this stage. In line with this observation, postmortem assessment of brain tissues demonstrated selective attenuation of inhibitory synaptic constituents accompanied by the upregulation of cFos before the formation of tau pathology in the forebrain at young ages. Our findings indicate that selective degeneration of inhibitory synapse with hyperexcitability in the cortical circuit constitutes the critical early pathophysiology of tauopathy.

The transcription factor Nurr1 has been identified to be ectopically induced in the striatum of rodents expressing l-DOPA-induced dyskinesia (LID). In the present study, we sought to characterize Nurr1 as a causative factor in LID expression. We used rAAV2/5 to overexpress Nurr1 or GFP in the parkinsonian striatum of LID-resistant Lewis or LID-prone Fischer-344 (F344) male rats. In a second cohort, rats received the Nurr1 agonist amodiaquine (AQ) together with l-DOPA or ropinirole. All rats received a chronic DA agonist and were evaluated for LID severity. Finally, we performed single-unit recordings and dendritic spine analyses on striatal medium spiny neurons (MSNs) in drug-naïve rAAV-injected male parkinsonian rats. rAAV-GFP injected LID-resistant hemi-parkinsonian Lewis rats displayed mild LID and no induction of striatal Nurr1 despite receiving a high dose of l-DOPA. However, Lewis rats overexpressing Nurr1 developed severe LID. Nurr1 agonism with AQ exacerbated LID in F344 rats. We additionally determined that in l-DOPA-naïve rats striatal rAAV-Nurr1 overexpression (1) increased cortically-evoked firing in a subpopulation of identified striatonigral MSNs, and (2) altered spine density and thin-spine morphology on striatal MSNs; both phenomena mimicking changes seen in dyskinetic rats. Finally, we provide postmortem evidence of Nurr1 expression in striatal neurons of l-DOPA-treated PD patients. Our data demonstrate that ectopic induction of striatal Nurr1 is capable of inducing LID behavior and associated neuropathology, even in resistant subjects. These data support a direct role of Nurr1 in aberrant neuronal plasticity and LID induction, providing a potential novel target for therapeutic development.

SIGNIFICANCE STATEMENT The transcription factor Nurr1 is ectopically induced in striatal neurons of rats exhibiting levodopa-induced dyskinesia [LID; a side-effect to dopamine replacement strategies in Parkinson's disease (PD)]. Here we asked whether Nurr1 is causing LID. Indeed, rAAV-mediated expression of Nurr1 in striatal neurons was sufficient to overcome LID-resistance, and Nurr1 agonism exacerbated LID severity in dyskinetic rats. Moreover, we found that expression of Nurr1 in l-DOPA naïve hemi-parkinsonian rats resulted in the formation of morphologic and electrophysiological signatures of maladaptive neuronal plasticity; a phenomenon associated with LID. Finally, we determined that ectopic Nurr1 expression can be found in the putamen of l-DOPA-treated PD patients. These data suggest that striatal Nurr1 is an important mediator of the formation of LID.

N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels that play critical roles in neuronal development and nervous system function. Here, we developed a model to study NMDARs in early development in zebrafish, by generating CRISPR-mediated lesions in the NMDAR genes, grin1a and grin1b, which encode the obligatory GluN1 subunits. While receptors containing grin1a or grin1b show high Ca²⁺ permeability, like their mammalian counterpart, grin1a is expressed earlier and more broadly in development than grin1b. Both grin1a^–/– and grin1b^–/– zebrafish are viable. Unlike in rodents, where the grin1 knockout is embryonic lethal, grin1 double-mutant fish (grin1a^–/–; grin1b^–/–), which lack all NMDAR-mediated synaptic transmission, survive until ~10 d dpf (days post fertilization), providing a unique opportunity to explore NMDAR function during development and in generating behaviors. Many behavioral defects in the grin1 double-mutant larvae, including abnormal evoked responses to light and acoustic stimuli, prey-capture deficits, and a failure to habituate to acoustic stimuli, are replicated by short-term treatment with the NMDAR antagonist MK-801, suggesting that they arise from acute effects of compromised NMDAR-mediated transmission. Other defects, however, such as periods of hyperactivity and alterations in place preference, are not phenocopied by MK-801, suggesting a developmental origin. Together, we have developed a unique model to study NMDARs in the developing vertebrate nervous system.

SIGNIFICANCE STATEMENT Rapid communication between cells in the nervous system depends on ion channels that are directly activated by chemical neurotransmitters. One such ligand-gated ion channel, the NMDAR, impacts nearly all forms of nervous system function. It has been challenging, however, to study the prolonged absence of NMDARs in vertebrates, and hence their role in nervous system development, due to experimental limitations. Here, we demonstrate that zebrafish lacking all NMDAR transmission are viable through early development and are capable of a wide range of stereotypic behaviors. As such, this zebrafish model provides a unique opportunity to study the role of NMDAR in the development of the early vertebrate nervous system.

"We thought it was a good idea to get a comprehensive record of the site while we could in case the water levels rise," says one official

Remote Isle au Haut is integrating time-tested technology with emerging innovations to create its own microgrid

<span class="topsy_trackback_comment"><span class="topsy_twitter_username"><span class="topsy_trackback_content">Squeekville, model train amusement park, on display at Children's ...: Squeekville, model train amusement park, ... http://bit.ly/9x4oFS</span></span>

Matteo Tranchellini and Moreno Monti created a coffee table book called CHICken to showcase the natural beauty of the ubiquitous birds.

The post 6th Graders Discover 3D Modeling with SOLIDWORKS Apps for Kids Classroom appeared first on SOLIDWORKS Education Blog.

Bank of England Working Papers by Aydan Dogan and Ida Hjortsoe

European Systemic Risk Board Occasional Papers by Greg Ros

AppleInsider has rounded up the best 16-inch MacBook Pro deals going on right now, with coupon savings knocking up to $450 off every single model. Whether you're in the market for a standard config or looking for a loaded Core i9 model, it pays to check out the cash discounts.

Every year SOLIDWORKS hosts one of the largest engineering conferences in the world. Since SOLIDWORKS World 2000, Model Mania® has been an attraction for many engineers wanting to show off their SOLIDWORKS skills. Model Mania, for those not familiar, is a

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It’s always interesting to know about some cool tricks that you can use when it comes to modelling within SOLIDWORKS. Well, within this blog we just happen to have one of those tricks for you. They always say a magician never

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Pursuant to Clearing Advisory 20-152 that was published on April 8th, the clearing house will switch the options pricing and valuation model to Bachelier to accommodate negative prices in the underlying futures and allow for listing of option contracts with negative strikes for the set of products specified in the link below. The switch will be effective for the margin cycle run at the end of trading tomorrow April 22, 2020 and will remain in place until further notice.

Click here for the full text of the advisory

20-170

One major goal of integrative and comparative biology is to understand and explain the interaction between the performance and behavior of animals in their natural environment. The Caviomorph, Octodon degu, is a native rodent species from Chile, and represents a unique model to study physiological and behavioral traits, including cognitive and sensory abilities. Degus live in colonies and have a well-structured social organization, with a mostly diurnal–crepuscular circadian activity pattern. More notable is the fact that in captivity, they reproduce and live between 5 and 7 yr and show hallmarks of neurodegenerative diseases (including Alzheimer's disease), diabetes, and cancer.

Two UK models predict the risk of mortality in very preterm Western infants (1) alive at onset of labor and (2) admitted for neonatal intensive care. Prognostic models need temporal and geographic validation to evaluate their performance.

The 2 models showed very good performance in a recent large cohort of very preterm infants born in another Western country. The accurate performance of both models suggests application in clinical practice (Read the full article)

Neglect cases in Child Protective Services often receive home-based interventions, but their success in preventing maltreatment recidivism has been elusive. Structured, behavioral skills models, such as SafeCare, are promising but have not been tested in full-scale implementation trials.

This cluster trial experiment demonstrates significant maltreatment recidivism reduction due to implementing the SafeCare model in a fully scaled-up statewide system. The findings support adopting the SafeCare model for these types of services. (Read the full article)

Febrile infants in the first 90 days may have life-threatening serious bacterial infection. Well-appearing febrile infants with serious bacterial infections cannot be distinguished from those without by examination alone. Variation in care resulting in both undertreatment and overtreatment is common.

The systemwide implementation of an evidence-based care process model for the care of febrile infants in Intermountain Healthcare was associated with increased delivery of evidence-based care, improved infant outcomes, and lower costs. This model adopted nationally can improve value. (Read the full article)

First drink before age 15 greatly increases the likelihood for later alcohol abuse or dependence. Separate investigations have linked many variables to alcohol initiation, but few have attempted to identify the optimal combination of predictors for age of alcohol initiation.

This article supports the screening questions selected in the joint National Institute on Alcohol Abuse and Alcoholism and the American Academy of Pediatrics initiative to identify and initiate intervention in youth at risk for early use of alcohol. (Read the full article)

The number of nurse practitioner graduates in the United States has nearly doubled over the past 2 decades. However, the number of pediatric nurse practitioner (PNP) graduates has remained relatively flat, although the demand for PNPs is expected to increase.

This study estimates the best-case shortage of PNPs over the next 25 years. We propose possible policy interventions to address key areas of the PNP workforce system and we compute their impact on the forecasted PNP shortage. (Read the full article)

Guidelines for postdischarge monitoring of hyperbilirubinemia for neonates of white descent are available from the American Academy of Pediatrics; however, such information for healthy term and late preterm Chinese neonates is lacking.

A classification model for predicting the risk of significant hyperbilirubinemia in Chinese neonates was developed that combines a transcutaneous bilirubin–based nomogram with clinical risk factors. It classified newborns into 6 risk groups, which can guide clinicians in planning appropriate follow-up strategies. (Read the full article)

Telacebec (Q203) is a new anti-tubercular drug with extremely potent activity against Mycobacterium ulcerans. Here, we explored the treatment-shortening potential of Q203 alone or in combination with rifampin (RIF) in a mouse footpad infection model. The first study compared Q203 at 5 and 10 mg/kg doses alone and with rifampin. Q203 alone rendered most mouse footpads culture-negative in 2 weeks. Combining Q203 with rifampin resulted in relapse-free cure 24 weeks after completing 2 weeks of treatment, compared to a 25% relapse rate in mice receiving RIF+clarithromycin, the current standard of care, for 4 weeks.

The second study explored the dose-ranging activity of Q203 alone and with RIF, including the extended activity of Q203 after treatment discontinuation. The bactericidal activity of Q203 persisted for ≥ 4 weeks beyond the last dose. All mice receiving just 1 week of Q203 at 2-10 mg/kg were culture-negative 4 weeks after stopping treatment. Mice receiving 2 weeks of Q203 at 0.5, 2 and 10 mg/kg were culture-negative 4 weeks after treatment. RIF did not increase the efficacy of Q203. A pharmacokinetics sub-study revealed that Q203 doses of 2-10 mg/kg in mice produce plasma concentrations similar to those produced by 100-300 mg doses in humans, with no adverse effect of RIF on Q203 concentrations.

These results indicate the extraordinary potential of Q203 to reduce the duration of treatment necessary for cure to ≤ 1 week (or 5 doses of 2-10 mg/kg) in our mouse footpad infection model and warrant further evaluation of Q203 in clinical trials.

Background. CLSI and EUCAST susceptibility breakpoints for voriconazole and C. albicans differ by one dilution (≤0.125 and ≤0.06 mg/l, respectively) whereas the epidemiological cutoff values (ECOFF/ECV) with both methodologies are the same (0.03 mg/L). We therefore determined the pharmacokinetic-pharmacodynamic (PK/PD) breakpoints of voriconazole against C. albicans for both methodologies with an in vitro PK/PD model, which was validated using existing animal PK/PD data.

Methods. Four clinical wild-type and non-wild-type C. albicans isolates (voriconazole MICs 0.008-0.125 mg/l) were tested in an in vitro PK/PD model. For validation purposes, mouse PK were simulated and in vitro PD were compared with in vivo outcome. Human PK were simulated and the exposure-effect relationship fAUC_0-24/MIC was described for EUCAST and CLSI24/48h methods. PK/PD breakpoints were determined using the fAUC_0-24/MIC associated with half-maximal activity (EI₅₀) and Monte Carlo simulation analysis.

Results. The in vitro 24h-PD EI₅₀ of voriconazole against C. albicans were 2.5-5 (1.5-17) fAUC/MIC. However, the 72h-PD were higher, 133 (51-347) fAUC/MIC for EUCAST and 94 (35-252) fAUC/MIC for CLSI. The mean (95% confidence interval) probability of target attainment (PTA) was 100(95-100)%, 97(72-100)%, 83(35-99)%, and 49(8-91)% and 100(97-100)%, 99(85-100)%, 91(52-100)% and 68(17-96)% for EUCAST and CLSI MICs 0.03, 0.06, 0.125, and 0.25 mg/L, respectively. Significantly, >95% PTAs were found for EUCAST/CLSI MICs ≤0.03 mg/ll. For MICs 0.06-0.125 mg/l trough levels 1-4 mg/ll would be required.

Conclusion. A PK/PD breakpoint of C. albicans voriconazole at the ECOFF/ECV of 0.03 mg/L was determined for both EUCAST/CLSI methods, indicating the need for breakpoint harmonization for the reference methodologies.

KBP-7072 is a semi-synthetic aminomethylcycline with broad-spectrum activity against Gram-positive and Gram-negative pathogens including multidrug resistant bacterial strains. The pharmacokinetics (PK) of KBP-7072 after oral and intravenous (IV) administration of single and multiple doses were investigated in animal models including during fed and fasted states and also evaluated the protein binding and excretion characteristics. In Sprague-Dawley (SD) rats, Beagle dogs, and CD-1 mice, KBP-7072 demonstrated a linear PK profile after administration of single oral and IV and multiple oral doses. Oral bioavailability ranged from 12% to 32%. Mean T_max ranged from 0.5 to 4 hours, and mean half-life ranged from approximately 6 to 11 hours. Administration of oral doses in the fed state resulted in a marked reduction in C_max and AUC compared with dosing in fasted animals. The mean bound fractions of KBP-7072 were 77.5%, 69.8%, 64.5%, 69.3%, and 69.2% in mouse, rat, dog, monkey, and human plasma, respectively. Following a single 22.5 mg/kg oral dose of KBP-7072 in SD rats, cumulative excretion in feces was 64% and in urine was 2.5% of the administered dose. The PK results in animal models are consistent with single and multiple ascending dose studies in healthy volunteers and confirm the suitability of KBP-7072 for once daily oral and IV administration in clinical studies.

Third-generation cephalosporin (3GC)-resistant Enterobacteriaceae are classified as critical priority pathogens, with extended-spectrum β-lactamases (ESBLs) as principal resistance determinants. Enmetazobactam (formerly AAI101) is a novel ESBL inhibitor developed in combination with cefepime for empiric treatment of serious Gram-negative infections in settings where ESBLs are prevalent. Cefepime-enmetazobactam has been investigated in a phase 3 trial in patients with complicated urinary tract infections or acute pyelonephritis. This study examined pharmacokinetic-pharmacodynamic (PK-PD) relationships of enmetazobactam, in combination with cefepime, for ESBL-producing isolates of Klebsiella pneumoniae in 26-hour murine neutropenic thigh infection models. Enmetazobactam dose fractionation identified time above a free threshold concentration (fT > C_T) as the PK-PD index predictive of efficacy. Nine ESBL-producing isolates of K. pneumoniae, resistant to cefepime and piperacillin-tazobactam, were included in enmetazobactam dose-ranging studies. The isolates encoded CTX-M-type, SHV-12, DHA-1 and OXA-48 β-lactamases and covered a cefepime-enmetazobactam MIC range from 0.06 to 2 μg/ml. Enmetazobactam restored the efficacy of cefepime against all isolates tested. Sigmoid curve fitting across the combined set of isolates identified enmetazobactam PK-PD targets for stasis and for a 1-log₁₀ bioburden reduction of 8% and 44% fT > 2 μg/ml, respectively, with a concomitant cefepime PK-PD target of 40 – 60% fT > cefepime-enmetazobactam MIC. These findings support clinical dose selection and breakpoint setting for cefepime-enmetazobactam.

The human diseases caused by the fungal pathogens Cryptococcus neoformans and C. gattii are associated with high indices of mortality, and toxic and/or cost-prohibitive therapeutic protocols. The need for affordable antifungals to combat cryptococcal disease is unquestionable. Previous studies suggested benzimidazoles as promising anti-cryptococcal agents combining low cost and high antifungal efficacy, but their therapeutic potential has not been demonstrated so far. In this study, we investigated the antifungal potential of fenbendazole, the most effective anti-cryptococcal benzimidazole. Fenbendazole was inhibitory against 17 different isolates of C. neoformans and C. gattii at a low concentration. The mechanism of anti-cryptococcal activity of fenbendazole involved microtubule disorganization, as previously described for human parasites. In combination with fenbendazole, the concentrations of the standard antifungal amphotericin B required to control cryptococcal growth were lower than those required when this antifungal was used alone. Fenbendazole was not toxic to mammalian cells. During macrophage infection, the anti-cryptococcal effects of fenbendazole included inhibition of intracellular proliferation rates and reduced phagocytic escape through vomocytosis. Fenbendazole deeply affected the cryptococcal capsule. In a mice model of cryptococcosis, the efficacy of fenbendazole to control animal mortality was similar to that observed for amphotericin B. These results indicate that fenbendazole is a promising candidate for the future development of an efficient and affordable therapeutic tool to combat cryptococcosis.

There are limited treatment options for enterococcal urinary tract infections, especially vancomycin-resistant Enterococcus (VRE). Oral fosfomycin is a potential option, although limited data are available guiding dosing and susceptibility. We undertook pharmacodynamic profiling of fosfomycin against E. faecalis and E. faecium isolates using a dynamic in vitro bladder infection model. Eighty-four isolates underwent fosfomycin agar dilution susceptibility testing (E. faecalis MIC_50/90 32/64 μg/mL; E. faecium MIC_50/90 64/128 μg/mL). Sixteen isolates (including E. faecalis ATCC 29212 and E. faecium ATCC 35667) were chosen to reflect the MIC range and tested in the bladder infection model with synthetic human urine (SHU). Under drug-free conditions, E. faecium demonstrated greater growth restriction in SHU compared to E. faecalis (E. faecium maximal growth 5.8 ± 0.6 log₁₀ CFU/mL; E. faecalis 8.0 ± 1.0 log₁₀ CFU/mL). Isolates were exposed to high and low fosfomycin urinary concentrations after a single dose, and two-doses given daily with low urinary exposure. Simulated concentrations closely matched the target (bias 2.3%). E. faecalis isolates required greater fosfomycin exposure for 3 log₁₀ kill from the starting inoculum compared with E. faecium. The fAUC_0-72/MIC and f%T > MIC_0-72 for E. faecalis was 672 and 70%, compared to 216 and 51% for E. faecium, respectively. There was no rise in fosfomycin MIC post-exposure. Two doses of fosfomycin with low urinary concentrations resulted in equivalent growth inhibition to a single dose with high urinary concentrations. With this urinary exposure, fosfomycin was effective in promoting suppression of regrowth (>3 log₁₀ kill) in the majority of isolates.

Omadacycline is a novel aminomethylcycline with activity against Gram-positive and -negative organisms, including Haemophilus influenzae, which is one of the leading causes of community-acquired bacterial pneumonia (CABP). The evaluation of antimicrobial agents against H. influenzae using standard murine infection models is challenging due to the low pathogenicity of this species in mice. Therefore, 24-hour dose-ranging studies using a one-compartment in vitro infection model were undertaken with the goal of characterizing the magnitude of the ratio of the area under the concentration-time curve (AUC) to the MIC (AUC/MIC ratio) associated with efficacy for a panel of five clinical H. influenzae isolates. These five isolates, which had MIC values of 1 or 2 mg/L, were exposed to omadacycline total-drug epithelial lining fluid (ELF) concentration-time profiles based on those observed in healthy volunteers following intravenous omadacycline administration. Relationships between change in log₁₀ colony forming units (CFU) from baseline at 24 hours and total-drug ELF AUC/MIC ratio for each isolate and the isolates pooled together were evaluated using Hill-type models and non-linear least squares regression. As evidenced by the high coefficient of determination (r²) of 0.88 to 0.98, total-drug ELF AUC/MIC ratio described the data well for each isolate and the isolates pooled together. The median total-drug ELF AUC/MIC ratio associated with net bacterial stasis and 1- and 2-log₁₀ CFU/mL reductions from baseline at 24 hours was 6.91, 8.91, and 11.1, respectively. These data were useful to support the omadacycline dosing regimens selected for the treatment of patients with CABP, as well as susceptibility breakpoints for H. influenzae.

Attention has been paid to H5N6 highly pathogenic avian influenza virus (HPAIV) because of its heavy burden on the poultry industry and human mortality. Since an influenza A virus carrying N6 neuraminidase (NA) has never spread in humans, the potential for H5N6 HPAIV to cause disease in humans and the efficacy of antiviral drugs against the virus need to be urgently assessed. We used non-human primates to elucidate the pathogenesis of H5N6 HPAIV as well as to determine the efficacy of antiviral drugs against the virus. H5N6 HPAIV infection led to high fever in cynomolgus macaques. The lung injury caused by the virus was severe with diffuse alveolar damage and neutrophil infiltration. In addition, an increase in IFN-α showed an inverse correlation with virus titers during the infection process. Oseltamivir was effective for reducing H5N6 HPAIV propagation, and continuous treatment with peramivir reduced virus propagation and severity of symptoms in the early stage. This study also showed the pathologically severe lung injury states in the cynomolgus macaques infected with H5N6 HPAIV, even in those that received early antiviral drug treatments, indicating the need for close monitoring and the need for further studies on the virus pathogenicity and new antiviral therapies.

One of the reasons for the lengthy tuberculosis (TB) treatment is the difficult to treat non-multiplying mycobacterial subpopulation. In order to assess the ability of (new) TB drugs to target this subpopulation, we need to incorporate dormancy models in our pre-clinical drug development pipeline. In most available dormancy models it takes a long time to create a dormant state and it is difficult to identify and quantify this non-multiplying condition.

The Mycobacterium tuberculosis 18b strain might overcome some of these problems, because it is dependent on streptomycin for growth and becomes non-multiplying after 10 days of streptomycin starvation, but still can be cultured on streptomycin-supplemented culture plates. We developed our 18b dormancy time-kill kinetic model to assess the difference in the activity of isoniazid, rifampicin, moxifloxacin and bedaquiline against log-phase growth compared to the non-multiplying M. tuberculosis subpopulation by CFU counting including a novel AUC-based approach as well as time-to-positivity (TTP) measurements.

We observed that isoniazid and moxifloxacin were relatively more potent against replicating bacteria, while rifampicin and high dose bedaquiline were equally effective against both subpopulations. Moreover, the TTP data suggest that including a liquid culture-based method could be of additional value as it identifies a specific mycobacterial subpopulation that is non-culturable on solid media.

In conclusion, the results of our study underline that the time-kill kinetics 18b dormancy model in its current form is a useful tool to assess TB drug potency and thus has its place in the TB drug development pipeline.

Background: MRSA pose significant therapeutic challenges, related to their: frequency in clinical infections; innate virulence properties; and propensity for multi-antibiotic resistance. MRSA are among the most common causes of endovascular infections, including infective endocarditis (IE).

Objective: To employ transthoracic echocardiography (TTE) to evaluate the effect of exebacase, a novel direct lytic agent, in experimental aortic valve MRSA IE.

Study Design: TTE was utilized to evaluate the in vivo effect of exebacase on MRSA-infected vegetation progression when combined with daptomycin (vs daptomycin alone). Primary intravegetation outcomes were: maximum size; weights at sacrifice; and MRSA counts at infection baseline vs after 4 days of daptomycin treatment (alone or in addition to exebacase administered once on treatment Day 1).

Results: A single dose of exebacase in addition to daptomycin cleared significantly more intravegetation MRSA than daptomycin alone. This was associated with a statistical trend toward reduced maximum vegetation size in the exebacase + daptomycin vs the daptomycin-alone therapy groups (p = 0.07). Also, mean vegetation weights in the exebacase-treated group were significantly lower vs daptomycin-alone (p < 0.0001). Maximum vegetation size by TTE correlated with vegetation weight (p = 0.005). In addition, intravegetation MRSA counts in the combination group were significantly lower vs untreated controls (p<0.0001) and the daptomycin-alone group (p<0.0001).

Conclusion: This study suggests that exebacase has a salutary impact on MRSA-infected vegetation progression when combined with daptomycin, especially in terms of vegetation MRSA burden, size and weight. Moreover, TTE appears to be an efficient non-invasive tool to assess therapeutic efficacies in experimental MRSA IE.

Treatment of exacerbations of chronic Pseudomonas aeruginosa infections in patients with cystic fibrosis (CF) is highly challenging due to hypermutability, biofilm formation and an increased risk of resistance emergence. We evaluated the impact of ciprofloxacin and meropenem as monotherapy and in combination in the dynamic in vitro CDC biofilm reactor (CBR). Two hypermutable P. aeruginosa strains, PAOmutS (MIC_{ciprofloxacin} 0.25 mg/L, MIC_meropenem 2 mg/L) and CW44 (MIC_{ciprofloxacin} 0.5 mg/L, MIC_meropenem 4 mg/L), were investigated for 120h. Concentration-time profiles achievable in epithelial lining fluid (ELF) following FDA-approved doses were simulated in the CBR. Treatments were ciprofloxacin 0.4g every 8h as 1h-infusions (80% ELF penetration), meropenem 6 g/day as continuous infusion (CI; 30% and 60% ELF penetration) and their combinations. Counts of total and less-susceptible planktonic and biofilm bacteria and MICs were determined. Antibiotic concentrations were quantified by UHPLC-PDA. For both strains, all monotherapies failed with substantial regrowth and resistance of planktonic (≥8log₁₀ CFU/mL) and biofilm (>8log₁₀ CFU/cm²) bacteria at 120h (MIC_{ciprofloxacin} up to 8 mg/L, MIC_meropenem up to 64 mg/L). Both combination treatments demonstrated synergistic bacterial killing of planktonic and biofilm bacteria of both strains from ~48h onwards and suppressed regrowth to ≤4log₁₀ CFU/mL and ≤6log₁₀ CFU/cm² at 120h. Overall, both combination treatments suppressed amplification of resistance of planktonic bacteria for both strains, and biofilm bacteria for CW44. The combination with meropenem at 60% ELF penetration also suppressed amplification of resistance of biofilm bacteria for PAOmutS. Thus, combination treatment demonstrated synergistic bacterial killing and resistance suppression against difficult-to-treat hypermutable P. aeruginosa strains.

Background

Optimal concentrations of unbound antimicrobials are essential for maximum microbiological effect. Although hypoalbuminemia and albumin fluid resuscitation are common in critical care, the effects of different albumin concentrations on the unbound concentrations of highly protein-bound antimicrobials are not known. The aim of this study was to compare effects of different albumin states on total and unbound concentrations of ertapenem and ceftriaxone using an ovine model.

Methods

Design

Prospective, three phase intervention observational study.

Subjects

Healthy Merino sheep.

Interventions

Eight sheep were subject to three experimental phases; normoalbuminemia, hypoalbuminemia using plasmapheresis and albumin replacement using a 25% albumin solution. In each phase, ceftriaxone 40 mg/kg and ertapenem 15 mg/kg were given intravenously. Blood samples were collected at pre-defined intervals and analyzed using an ultra-high-performance liquid chromatography tandem mass spectrometry method. Pharmacokinetic parameters such as area under the curve (AUC_0-24), plasma clearance (CL) and apparent volume of distribution in the terminal phase (V_d) were estimated and compared between the phases.

Results

The protein and albumin concentrations were significantly different between phases. Hypoalbuminemia resulted in a significantly lower AUC_0-24 and higher CL of total and unbound concentrations of ceftriaxone compared to the other phases. Whereas albumin replacement led to higher AUC_0-24 and lower CL compared to other phases for both drugs. The V_d for total drug concentrations for both drugs were significantly lower with albumin replacement.

Conclusions

For highly protein-bound drugs such as ceftriaxone and ertapenem, both hypoalbuminemia and albumin replacement may affect unbound drug exposure.

In an effort to help mitigate the disruptive effects of the deadly COVID-19 virus, an interdisciplinary team of Penn State researchers are developing a novel methodology to analyze its spread and the impacts on policy to create better-prepared and more-resilient health care systems.

For Norwegian international striker Ada Hegerberg, inspiring the next generation of women's players is a personal goal. In an interview which appears in the Women's U17 EURO tournament programme, we hear that the Olympique Lyonnais star wants budding young players to feel her same love of the game.

Teacher-preparation programs need to better prepare teachers, and especially white teachers, to serve students and communities of colors more effectively, the report says.

The Model 3 was on Autopilot and managed to rear-end the police car which had stopped to assist a disabled vehicle and had its emergency lights activated.

From the ashes of the failed Fisker Karma sports car, automotive designer Henrik Fisker has designed a futuristic battery-powered luxury SUV that won't break the bank.

We expected the Model Y to ship in the Fall with a 280 mile range, but now it's shipping in March with a 315 mile range.

A new process to harness multiple disease models for outbreak management has been developed by an international team of researchers. The team will immediately implement the process to help inform policy decisions for the COVID-19 outbreak.

"Thank you, parents, for being the best kind of role models. We are because of you," posted Sonam

Review of: Modelling Transitions: Virtues, Vices, Visions of the Future by Moallemi, Enayat A. and de Haan, Fjalar J. (Eds.), reviewed by Cesar Garcia-Diaz