Discovery and SAR of methylated tetrahydropyranyl derivatives as inhibitors of isoprenylcysteine carboxyl methyltransferase (ICMT)

A series of tetrahydropyranyl (THP) derivatives has been developed as potent inhibitors of isoprenylcysteine carboxyl methyltransferase (ICMT) for use as anticancer agents. Structural modification of the submicromolar hit compound 3 led to the potent 3-methoxy substituted analogue 27. Further SAR development around the THP ring resulted in an additional 10-fold increase in potency, exemplified by analogue 75 with an IC(50) of 1.3 nM. Active and potent compounds demonstrated a dose-dependent increase in Ras cytosolic protein. Potent ICMT inhibitors also reduced cell viability in several cancer cell lines with growth inhibition (GI(50)) values ranging from 0.3 to >100 μM. However, none of the cellular effects observed using ICMT inhibitors were as pronounced as those resulting from a farnesyltransferase inhibitor.     

Isolation of highly pathogenic H5N6 avian influenza virus in Southern Vietnam with genetic similarity to those infecting humans in China

Since 2013, H5N6 highly pathogenic avian influenza viruses (HPAIVs) have been responsible for outbreaks in poultry and wild birds around Asia. H5N6 HPAIV is also a public concern due to sporadic human infections being reported in China. In the current study, we isolated an H5N6 HPAIV strain (A/Muscovy duck/Long An/AI470/2018; AI470) from an outbreak at a Muscovy duck farm in Long An Province in Southern Vietnam in July 2018 and genetically characterized it. Basic Local Alignment Search Tool (BLAST) analysis revealed that the eight genomic segments of AI470 were most closely related (99.6%–99.9%) to A/common gull/Saratov/1676/2018 (H5N6), which was isolated in October 2018 in Russia. Furthermore, AI470 also shared 99.4%–99.9% homology with A/Guangxi/32797/2018, an H5N6 HPAIV strain that infected humans in China in 2018. Phylogenetic analyses of the entire genome showed that AI470 was directly derived from H5N6 HPAIVs that were in South China from 2015 to 2018 and clustered with four H5N6 HPAIV strains of human origin in South China from 2017 to 2018. This indicated that AI470 was introduced into Vietnam from China. In addition, molecular characteristics related to mammalian adaptation among the recent human H5N6 HPAIV viruses, except PB2 E627K, were shared by AI470. These findings are cause for concern since H5N6 HPAIV strains that possess a risk of human infection have crossed the Chinese border.     

Optical coherence tomography for high-resolution imaging of mouse development in utero

Although the mouse is a superior model to study mammalian embryonic development, high-resolution live dynamic visualization of mouse embryos remain a technical challenge. We present optical coherence tomography as a novel methodology for live imaging of mouse embryos through the uterine wall thereby allowing for time lapse analysis of developmental processes and direct phenotypic analysis of developing embryos. We assessed the capability of the proposed methodology to visualize structures of the living embryo from embryonic stages 12.5 to 18.5 days postcoitus. Repetitive in utero embryonic imaging is demonstrated. Our work opens the door for a wide range of live, in utero embryonic studies to screen for mutations and understand the effects of pharmacological and toxicological agents leading to birth defects.     

Characterization of the cellular and antitumor effects of MPI-0479605, a small-molecule inhibitor of the mitotic kinase Mps1

Mps1 is a dual specificity protein kinase that is essential for the bipolar attachment of chromosomes to the mitotic spindle and for maintaining the spindle assembly checkpoint until all chromosomes are properly attached. Mps1 is expressed at high levels during mitosis and is abundantly expressed in cancer cells. Disruption of Mps1 function induces aneuploidy and cell death. We report the identification of MPI-0479605, a potent and selective ATP competitive inhibitor of Mps1. Cells treated with MPI-0479605 undergo aberrant mitosis, resulting in aneuploidy and formation of micronuclei. In cells with wild-type p53, this promotes the induction of a postmitotic checkpoint characterized by the ATM- and RAD3-related-dependent activation of the p53-p21 pathway. In both wild-type and p53 mutant cells lines, there is a growth arrest and inhibition of DNA synthesis. Subsequently, cells undergo mitotic catastrophe and/or an apoptotic response. In xenograft models, MPI-0479605 inhibits tumor growth, suggesting that drugs targeting Mps1 may have utility as novel cancer therapeutics.     

Stimulation of entorhinal cortex promotes adult neurogenesis and facilitates spatial memory

Deep brain stimulation (DBS) is an established therapeutic modality for the treatment of movement disorders and an emerging therapeutic approach for the treatment of disorders of mood and thought. For example, recently we have shown that DBS of the fornix may ameliorate cognitive decline associated with dementia. However, like other applications of DBS, the mechanisms mediating these clinical effects are unknown. As DBS modulates neurophysiological activity in targeted brain regions, DBS might influence cognitive function via activity-dependent regulation of hippocampal neurogenesis. Using stimulation parameters analogous to clinical high-frequency DBS, here we addressed this question in mice. We found that acute stimulation of the entorhinal cortex (EC) transiently promoted proliferation in the dentate gyrus (DG). Cells generated as a consequence of stimulation differentiated into neurons, survived for at least several weeks, and acquired normal dentate granule cell (DGC) morphology. Importantly, stimulation-induced promotion of neurogenesis was limited to the DG and not associated with changes in apoptotic cell death. Using immunohistochemical approaches, we found that, once sufficiently mature, these stimulation-induced neurons integrated into hippocampal circuits supporting water-maze memory. Finally, formation of water-maze memory was facilitated 6 weeks (but not 1 week) after bilateral stimulation of the EC. The delay-dependent nature of these effects matches the maturation-dependent integration of adult-generated DGCs into dentate circuits supporting water-maze memory. Furthermore, because the beneficial effects of EC stimulation were prevented by blocking neurogenesis, this suggests a causal relationship between stimulation-induced promotion of adult neurogenesis and enhanced spatial memory.     

Results of the influenza virus surveillance in wild birds in Western part of Mongolia

ObjectiveTo present results of virological study of wild birds inhabiting Western Mongolia.MethodsOver a period of 2003–2008, we isolated 13 influenza A viruses: H1N1, H3N6, H13N8 and H4N6 subtypes. We did not isolate any H5N1 subtype, that still cause epizooty in wild birds and poultry.ResultsWe revealed taxonomic and ecological heterogeneity of the birds involved in maintenance of circulation of influenza viruses in the given territory. Influenza viruses were isolated from birds of 6 orders; among them there are species preferring water and semi-aquatic biotopes, one species preferring dry plain region, and also one species which can inhabit both dry and water biotopes.ConclusionsRepresentatives of all main orders of Western Mongolia avifauna are involved in support of influenza A virus circulation, highly pathogenic H5N1 influenza viruses were registered in Mongolia thus it's necessary to continue permanent influenza virus surveillance in wild birds' populations.     

Tumor suppressor protein kinase Chk2 is a mediator of anoikis of intestinal epithelial cells

Resistance of carcinoma cells to anoikis, apoptosis that is normally induced by detachment of nonmalignant epithelial cells from the extracellular matrix, is thought to be critical for carcinoma progression. Molecular mechanisms that control anoikis of nonmalignant and cancer cells are understood poorly. In an effort to understand them we found that detachment of nonmalignant intestinal epithelial cells triggers upregulation of Chk2, a pro-apoptotic protein kinase that has never been implicated in anoikis and has been thought to kill cells mainly under the conditions compromising genome integrity. We found that enforced downregulation of Chk2 protects intestinal epithelial cells from anoikis. Chk2 can kill cells by stabilizing p53 tumor suppressor protein or via p53-independent mechanisms, and we established that Chk2-mediated anoikis of intestinal epithelial cells is p53-independent. We further found that, unlike nonmalignant intestinal epithelial cells whose anoikis is triggered by detachment-induced Chk2 upregulation, intestinal epithelial cells carrying oncogenic ras, a known inhibitor of anoikis, remain anoikis-resistant in response to enforced Chk2 upregulation. By contrast, drugs, such as topoisomerase I inhibitors, that can kill cells via Chk2-indpendent mechanisms, efficiently triggered anoikis of ras-transformed cells. Thus, oncogenic ras can prevent Chk2 from triggering anoikis even when levels of this protein kinase are elevated in cancer cells, and the use of therapeutic agents that kill cells in a Chk-2-independent, rather than Chk-2-dependent, manner could represent an efficient strategy for overcoming ras-induced anoikis resistance of these cells. We conclude that Chk-2 is an important novel component of anoikis-promoting machinery of intestinal epithelial cells.     

Prescribing in maternity care in Russia: the legacy of Soviet medicine

Remarkably, there has been very little detailed research on clinical practice in Russia and its neighbours in what was the USSR, even though it is known that the USSR was isolated from many international developments, in particular evidence-based medicine. In this study we examine obstetric practice, an area of practice where there is an extensive body of evidence on the appropriateness of many interventions. The study is undertaken in Tula, a region 200 km south of Moscow. Building on earlier detailed analyses of data from the facilities in the region, it reports a series of structured interviews with 52 obstetricians from all 19 facilities in the region, designed to identify patterns of prescribing, supplemented by 36 more detailed re-interviews to explore reasons for the differing practices. The study demonstrates a widespread divergence from internationally accepted practice. Maternity care is extremely medicalised but many non-evidence based medicines are used. Some are heavily marketed by large pharmaceutical companies, some were widely used during the Soviet period but never evaluated, and a few are not known to be used anywhere else in the world. For several conditions, the most widely used drugs are clearly inferior to alternative products and some are used for indications quite different from those in other countries. This study contributes to the growing evidence that much of the care provided in Russian maternity units is ineffective or potentially dangerous but also begins to offer some explanations for why this is, including a lack of access to information and a lack of awareness of the concept of evidence-based practice.     

Learning nonnative speech sounds changes local encoding in the adult human cortex

Adults can learn to identify nonnative speech sounds with training, albeit with substantial variability in learning behavior. Increases in behavioral accuracy are associated with increased separability for sound representations in cortical speech areas. However, it remains unclear whether individual auditory neural populations all show the same types of changes with learning, or whether there are heterogeneous encoding patterns. Here, we used high-resolution direct neural recordings to examine local population response patterns, while native English listeners learned to recognize unfamiliar vocal pitch patterns in Mandarin Chinese tones. We found a distributed set of neural populations in bilateral superior temporal gyrus and ventrolateral frontal cortex, where the encoding of Mandarin tones changed throughout training as a function of trial-by-trial accuracy (“learning effect”), including both increases and decreases in the separability of tones. These populations were distinct from populations that showed changes as a function of exposure to the stimuli regardless of trial-by-trial accuracy. These learning effects were driven in part by more variable neural responses to repeated presentations of acoustically identical stimuli. Finally, learning effects could be predicted from speech-evoked activity even before training, suggesting that intrinsic properties of these populations make them amenable to behavior-related changes. Together, these results demonstrate that nonnative speech sound learning involves a wide array of changes in neural representations across a distributed set of brain regions.

Humans are finely attuned to the sounds in their native language (1, 2), driven by extensive experience hearing these sounds in many different contexts from different speakers (3–5). However, for nonnative sounds in unfamiliar languages, adult listeners often struggle to learn to recognize relatively simple contrasts (6–9). For example, although native English listeners understand how changes in vocal pitch indicate intonational prosody (e.g., statements versus questions; refs. 10 and 11), this does not translate to the ability to easily identify the syllable-level pitch patterns that define lexical tones in Mandarin Chinese (12, 13). Fundamentally, this difficulty may reflect a trade-off between maintaining stable representations of deeply engrained speech sounds and retaining enough plasticity to be able to continue to learn behaviorally relevant information throughout the lifespan (14–19). Learning to identify nonnative speech sounds often requires long and intense periods of active training (12, 20–22), consistent with the observation that speech circuits in the human brain are resistant to change following developmental critical periods (15, 17).However, even brief training periods can lead to an increased ability to identify novel speech sounds, albeit with highly variable performance across individuals (23–25). Behavioral evidence has further shown that the way listeners perceive relevant auditory cues changes after speech training (14, 25–27), which has led to the hypothesis that learning is rooted in more distinct neural representations of those sounds (17, 27). Consistent with this hypothesis, previous neuroimaging studies have shown that activation in frontotemporal areas increases following identification or discrimination tasks (13, 19, 28–30). These increases in the magnitude of activation are further associated with greater neural separability among sound categories for both speech (31–33) and nonspeech sounds (34–36). However, recent evidence suggests a highly diverse set of speech representations even within areas like the superior temporal gyrus (STG; ref. 37). Currently, the extent to which learning-related changes vary at the level of local populations remains unknown due to the broad spatial scale of noninvasive methods, which may obscure more complex dynamics. In addition, it is unclear how learning-related changes evolve on a trial-by-trial basis, as listeners initially learn to use the stimulus dimensions that allow them to achieve increased accuracy on the task, since most previous work examines neural activity only at early and late stages of the task.Here, we examined the relationship between behavioral performance during the initial stage of nonnative speech sound learning and the trial-by-trial encoding of speech content in local neural populations in the human brain. English-speaking participants listened to unfamiliar Mandarin syllables and learned to identify tone categories (22, 38), while neural activity was recorded from electrocorticography (ECoG) arrays placed over lateral cortical areas. We hypothesized that, as listeners heard the same stimuli across multiple exposures, some neural populations would show responses to Mandarin speech sounds that track the trial-by-trial fluctuations in participants’ behavioral performance during learning, and we also asked whether these changes would be uniformly reflected in increased separability among tones. We further hypothesized that these learning-related neural populations would be distinct from other potential patterns of change across trials that do not directly correlate with learning (e.g., the number of exposures to a given token, independent from accuracy) and neural populations that show stable activity patterns across trials. To address the relationship to stimulus feature encoding (e.g., pitch representations for English intonational prosody; ref. 39), we also measured the extent to which neural responses to unfamiliar Mandarin speech sounds prior to training can be used to predict the emergence of learning-related changes during training.We found a subset of local populations across the cortical surface that track trial-by-trial accuracy, even when learning performance is relatively low and variable. These learning-related effects manifest as both increases and decreases in the amplitude of neural responses to specific speech sounds and are spatially interspersed and dissociable from those that arise simply as a function of repeated exposure. Furthermore, learning-related changes are associated with higher variability of the response amplitude across repeated exposures to the same acoustic stimulus, suggesting less robust emergent neural representations. Finally, we show that intrinsic properties of these neural populations are associated with whether they show learning-related effects during training, allowing us to predict whether these effects will occur based on responses to the novel speech sounds prior to training. Together, these results demonstrate that learning to identify novel speech sounds scaffolds on existing sensitivities to relevant features and that the initial stages of learning a new language involve a specific set of processes to fine-tune local speech representations in the brain. We propose that the learning-induced increased neural separability in frontotemporal regions arises from heterogeneous changes among local populations, which comprise those regions.