CRISPR-Cas in mobile genetic elements: counter-defence and beyond

The principal function of CRISPR-Cas systems in archaea and bacteria is defence against mobile genetic elements (MGEs), including viruses, plasmids and transposons. However, the relationships between CRISPR-Cas and MGEs are far more complex. Several classes of MGE contributed to the origin and evolution of CRISPR-Cas, and, conversely, CRISPR-Cas systems and their components were recruited by various MGEs for functions that remain largely uncharacterized. In this Analysis article, we investigate and substantially expand the range of CRISPR-Cas components carried by MGEs. Three groups of Tn7-like transposable elements encode 'minimal' type I CRISPR-Cas derivatives capable of target recognition but not cleavage, and another group encodes an inactivated type V variant. These partially inactivated CRISPR-Cas variants might mediate guide RNA-dependent integration of the respective transposons. Numerous plasmids and some prophages encode type IV systems, with similar predicted properties, that appear to contribute to competition among plasmids and between plasmids and viruses. Many prokaryotic viruses also carry CRISPR mini-arrays, some of which recognize other viruses and are implicated in inter-virus conflicts, and solitary repeat units, which could inhibit host CRISPR-Cas systems.

Peptide-based covalent inhibitors of MALT1 paracaspase

Potent and selective substrate-based covalent inhibitors of MALT1 protease were developed from the tetrapeptide tool compound Z-VRPR-fmk. To improve cell permeability, we replaced one arginine residue. We further optimized a series of tripeptides and identified compounds that were potent in both a GloSensor reporter assay measuring cellular MALT1 protease activity, and an OCI-Ly3 cell proliferation assay. Example compounds showed good overall selectivity towards cysteine proteases, and one compound was selected for further profiling in ABL-DLBCL cells and xenograft efficacy models.

Quinoline and thiazolopyridine allosteric inhibitors of MALT1

Quinolines and thiazolopyridines were developed as allosteric inhibitors of MALT1, with good cellular potency and exquisite selectivity. Mouse pharmacokinetic (PK) profiling showed these to have low in vivo clearance, and moderate oral exposure. The thiazolopyridines were less lipophilic than the quinolines, and one thiazolopyridine example was active in our hIL10 mouse pharmacodynamic (PD) model upon oral dosing.

Cigarette smoke reduces short chain fatty acid production by a Porphyromonas gingivalis clinical isolate

Objectives

We hypothesized that short chain fatty acid (SCFA) production by oral pathogens is suppressed by exposure to cigarette smoke extract (CSE).

Background

Tobacco smoking is a major risk factor for plaque‐induced periodontal diseases. Despite increased disease susceptibility, overt oral inflammation is suppressed in smokers, presenting a diagnostic conundrum. Bacterial‐derived SCFAs can penetrate into oral tissues where they influence multiple components of immune and healing responses. Indeed, the SCFA burden has been correlated with the inflammatory condition of the gingiva. However, the influence of cigarette consumption on SCFA production is unknown.

Methods

GC/MS was employed to monitor the production of several SCFAs (propionic acid, isobutyric acid, butyric acid, and isovaleric acid) by representative anaerobic oral pathogens (Filifactor alocis 35896, Fusobacterium nucleatum 25586, Porphyromonas gingivalis 33277) that were exposed, or not, to a physiologically relevant dose of CSE (2000 ng/ml nicotine equivalents) generated from 3R4F reference cigarettes.

Results

The growth of all three bacterial species was unaffected by CSE. The capacity to produce SCFAs by these bacteria was highly varied. F alocis produced the highest concentration of a specific SCFA (butyrate); P gingivalis provided the most robust overall SCFA signal, while F alocis and F nucleatum did not release detectable levels of isobutyrate or isovalerate. As P gingivalis 33277 was the broadest SCFA producer, three low‐passage clinical isolates (10208C, 5607, and 10512) were also examined. Compared to unconditioned microbes, reduced SCFA release was apparent in CSE‐exposed low‐passage clinical isolates of P gingivalis which reached significance for one of the three isolates (propionic, isobutyric, butyric, and isovaleric acids, all P < 0.05).

Conclusions

There is high disparity in the SCFA profiles of variant chronic periodontitis‐associated bacteria, while CSE exposure reduces SCFA production by a specific clinical strain of P gingivalis. If the latter phenomenon occurs in vivo, a reduced SCFA burden may help explain the reduced vascular response to dental plaque in tobacco smokers.

Restrictive compared with liberal red cell transfusion strategies in cardiac surgery: a meta-analysis

AIMS

To determine whether a restrictive strategy of red blood cell (RBC) transfusion at lower haemoglobin concentrations is inferior to a liberal strategy of RBC transfusion at higher haemoglobin concentrations in patients undergoing cardiac surgery.

METHODS AND RESULTS

We conducted a systematic review, meta-analysis, and trial sequential analysis of randomized controlled trials of the effect of restrictive and liberal RBC transfusion strategies on mortality within 30 days of surgery as the primary outcome. Secondary outcomes were those potentially resulting from anaemia-induced tissue hypoxia and transfusion outcomes. We searched the electronic databases MEDLINE, EMBASE, and the Cochrane Library until 17 November 2017. Thirteen trials were included. The risk ratio (RR) of mortality derived from 4545 patients assigned to a restrictive strategy when compared with 4547 transfused according to a liberal strategy was 0.96 [95% confidence interval (CI) 0.76-1.21, I2 = 0]. A restrictive strategy did not have a statistically significant effect on the risk of myocardial infarction (RR 1.01, 95% CI 0.81-1.26; I2=0), stroke (RR 0.93, 95% CI 0.68-1.27, I2 = 0), renal failure (RR 0.96, 95% CI 0.76-1.20, I2 = 0), or infection (RR 1.12, 95% CI 0.98-1.29, I2 = 0). Subgroup analysis of adult and paediatric trials did not show a significant interaction. At approximately 70% of the critical information size, the meta-analysis of mortality crossed the futility boundary for inferiority of the restrictive strategy.

CONCLUSION

The current evidence does not support the notion that restrictive RBC transfusion strategies are inferior to liberal RBC strategies in patients undergoing cardiac surgery.

Microbiological and biochemical findings in relation to clinical periodontal status in active smokers, non-smokers and passive smokers

INTRODUCTION

Cigarette users are more susceptible than non-smokers to periodontitis, a bacterial-induced, inflammation-driven, destructive disease of the supporting tissues of the teeth. We hypothesized that clinical periodontal findings and microbiological and/or inflammatory marker levels would be intermediate in those exposed to environmental tobacco smoke compared to active smokers and non-smokers.

METHODS

Sixty individuals were recruited from a University periodontal clinic and assigned as non-smokers, active smokers or passive-smokers according to their self reports. Clinical periodontal measurements, comprising plaque index, probing depth (PD), clinical attachment level (CAL) and bleeding on probing, were recorded at six sites per tooth. Cotinine levels were determined in whole saliva samples by EIA. Treponema denticola and Porphyromonas gingivalis infection was determined by PCR, while matrix metalloproteinase-8 (MMP-8) and interleukin-8 (IL-8) concentrations were determined by ELISA.

RESULTS

Study groups were subsequently reassigned in accordance with the cotinine data. The smoker group exhibited higher mean PD and CAL values compared to the non-smoker group (p<0.05). Passive-smokers exhibited PD and CAL values smaller than those of the active smokers and greater than those of the non-smokers, but the differences were not statistically significant. PD and CAL values correlated with cotinine concentrations (p<0.05). P. gingivalis infection was noted in most subjects, irrespective of smoking status. T. denticola infection was noted in 4/23 (17.4%) smokers, 0/16 (0%) environmentally-exposed recruits and 2/21 (9.5%) non-smokers. Salivary MMP-8 and IL-8 levels were lower in smokers compared to both non-smokers and passive-smokers but the differences were not significant (all p>0.05).

CONCLUSIONS

The present clinical periodontal findings provide further support for a negative, dose-related effect of tobacco exposure on periodontal health. The tendency for a more prevalent detection of T. denticola and for a suppressed inflammatory response observed in the smokers may partly explain the increased susceptibility to periodontal tissue destruction, but needs to be verified in larger scale studies.

Increased Serine and One-Carbon Pathway Metabolism by PKCλ/ι Deficiency Promotes Neuroendocrine Prostate Cancer

Increasingly effective therapies targeting the androgen receptor have paradoxically promoted the incidence of neuroendocrine prostate cancer (NEPC), the most lethal subtype of castration-resistant prostate cancer (PCa), for which there is no effective therapy. Here we report that protein kinase C (PKC)λ/ι is downregulated in de novo and during therapy-induced NEPC, which results in the upregulation of serine biosynthesis through an mTORC1/ATF4-driven pathway. This metabolic reprogramming supports cell proliferation and increases intracellular S-adenosyl methionine (SAM) levels to feed epigenetic changes that favor the development of NEPC characteristics. Altogether, we have uncovered a metabolic vulnerability triggered by PKCλ/ι deficiency in NEPC, which offers potentially actionable targets to prevent therapy resistance in PCa.

Postoperative cognitive dysfunction after sevoflurane or propofol general anaesthesia in combination with spinal anaesthesia for hip arthroplasty

It is unknown if the type of general anaesthetic used for maintenance of anaesthesia affects the incidence of postoperative cognitive dysfunction (POCD). The aim of this study was to compare the incidence of POCD in patients administered either sevoflurane or propofol for maintenance of anaesthesia during total hip replacement surgery. Following administration of a spinal anaesthetic, patients received either sevoflurane (n=121) or propofol (n=171) at the discretion of the anaesthetist for maintenance of general anaesthesia to maintain the processed electroencephalogram (bispectral index, BIS) under 60. POCD was assessed postoperatively at day 7, three months, and 12 months using a neurocognitive test battery. There was no statistically significant difference between the incidence of POCD at any timepoint with sevoflurane compared to propofol. The mean BIS was significantly lower in the sevoflurane group than in the propofol group (mean BIS 44.3 [standard deviation, SD 7.5] in the sevoflurane group versus 53.7 [SD 8.1] in the propofol group, <i>P</i>=0.0001). However, there was no statistically significant association between intraoperative BIS level and the incidence of POCD at any timepoint. Our results suggest that the incidence of POCD is not strongly influenced by the type of anaesthesia used in elderly patients.

Critical appraisal of nonrandomized studies-A review of recommended and commonly used tools

RATIONALE, AIMS, AND OBJECTIVES

When randomized controlled trial data are limited or unavailable, or to supplement randomized controlled trial evidence, health technology assessment (HTA) agencies may rely on systematic reviews of nonrandomized studies (NRSs) for evidence of the effectiveness of health care interventions. NRS designs may introduce considerable bias into systematic reviews, and several methodologies by which to evaluate this risk of bias are available. This study aimed to identify tools commonly used to assess bias in NRS and determine those recommended by HTA bodies.

METHODS

Appraisal tools used in NRS were identified through a targeted search of systematic reviews (January 2013-March 2017; MEDLINE and EMBASE [OVID SP]). Recommendations for the critical appraisal of NRS by expert review groups and HTA bodies were reviewed.

RESULTS

From the 686 studies included in the narrative synthesis, 48 critical appraisal tools were identified. Commonly used tools included the Newcastle-Ottawa Scale, the methodological index for NRS, and bespoke appraisal tools. Neither the Cochrane Handbook nor the Centre for Reviews and Dissemination recommends a particular instrument for the assessment of risk of bias in NRS, although Cochrane has recently developed their own NRS critical appraisal tool. Among HTA bodies, only the Canadian Agency for Drugs and Technologies in Health recommends use of a specific critical appraisal tool-SIGN 50 (for cohort or case-control studies). Several criteria including reporting, external validity, confounding, and power were examined.

CONCLUSION

There is no consensus between HTA groups on the preferred appraisal tool. Reviewers should select from a suite of tools on the basis of the design of studies included in their review.

A novel small molecule that kills a subset of MLL-rearranged leukemia cells by inducing mitochondrial dysfunction

Survival rates for pediatric patients suffering from mixed lineage leukemia (MLL)-rearranged leukemia remain below 50% and more targeted, less toxic therapies are urgently needed. A screening method optimized to discover cytotoxic compounds selective for MLL-rearranged leukemia identified CCI-006 as a novel inhibitor of MLL-rearranged and CALM-AF10 translocated leukemias that share common leukemogenic pathways. CCI-006 inhibited mitochondrial respiration and induced mitochondrial membrane depolarization and apoptosis in a subset (7/11, 64%) of MLL-rearranged leukemia cell lines within a few hours of treatment. The unresponsive MLL-rearranged leukemia cells did not undergo mitochondrial membrane depolarization or apoptosis despite a similar attenuation of mitochondrial respiration by the compound. In comparison to the sensitive cells, the unresponsive MLL-rearranged leukemia cells were characterized by a more glycolytic metabolic phenotype, exemplified by a more pronounced sensitivity to glycolysis inhibitors and elevated HIF1α expression. Silencing of HIF1α expression sensitized an intrinsically unresponsive MLL-rearranged leukemia cell to CCI-006, indicating that this pathway plays a role in determining sensitivity to the compound. In addition, unresponsive MLL-rearranged leukemia cells expressed increased levels of MEIS1, an important leukemogenic MLL target gene that plays a role in regulating metabolic phenotype through HIF1α. MEIS1 expression was also variable in a pediatric MLL-rearranged ALL patient dataset, highlighting the existence of a previously undescribed metabolic variability in MLL-rearranged leukemia that may contribute to the heterogeneity of the disease. This study thus identified a novel small molecule that rapidly kills MLL-rearranged leukemia cells by targeting a metabolic vulnerability in a subset of low HIF1α/low MEIS1-expressing MLL-rearranged leukemia cells.

Functionally diverse type V CRISPR-Cas systems

Type V CRISPR-Cas systems are distinguished by a single RNA-guided RuvC domain-containing effector, Cas12. Although effectors of subtypes V-A (Cas12a) and V-B (Cas12b) have been studied in detail, the distinct domain architectures and diverged RuvC sequences of uncharacterized Cas12 proteins suggest unexplored functional diversity. Here, we identify and characterize Cas12c, -g, -h, and -i. Cas12c, -h, and -i demonstrate RNA-guided double-stranded DNA (dsDNA) interference activity. Cas12i exhibits markedly different efficiencies of CRISPR RNA spacer complementary and noncomplementary strand cleavage resulting in predominant dsDNA nicking. Cas12g is an RNA-guided ribonuclease (RNase) with collateral RNase and single-strand DNase activities. Our study reveals the functional diversity emerging along different routes of type V CRISPR-Cas evolution and expands the CRISPR toolbox.

Recommendations for the nomenclature of cognitive change associated with anaesthesia and surgery-2018

Cognitive change affecting patients after anaesthesia and surgery has been recognised for more than 100 yr. Research into cognitive change after anaesthesia and surgery accelerated in the 1980s when multiple studies utilised detailed neuropsychological testing for assessment of cognitive change after cardiac surgery. This body of work consistently documented decline in cognitive function in elderly patients after anaesthesia and surgery, and cognitive changes have been identified up to 7.5 yr afterwards. Importantly, other studies have identified that the incidence of cognitive change is similar after non-cardiac surgery. Other than the inclusion of non-surgical control groups to calculate postoperative cognitive dysfunction, research into these cognitive changes in the perioperative period has been undertaken in isolation from cognitive studies in the general population. The aim of this work is to develop similar terminology to that used in cognitive classifications of the general population for use in investigations of cognitive changes after anaesthesia and surgery. A multispecialty working group followed a modified Delphi procedure with no prespecified number of rounds comprised of three face-to-face meetings followed by online editing of draft versions. Two major classification guidelines [Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5) and National Institute for Aging and the Alzheimer Association (NIA-AA)] are used outside of anaesthesia and surgery, and may be useful for inclusion of biomarkers in research. For clinical purposes, it is recommended to use the DSM-5 nomenclature. The working group recommends that 'perioperative neurocognitive disorders' be used as an overarching term for cognitive impairment identified in the preoperative or postoperative period. This includes cognitive decline diagnosed before operation (described as neurocognitive disorder); any form of acute event (postoperative delirium) and cognitive decline diagnosed up to 30 days after the procedure (delayed neurocognitive recovery) and up to 12 months (postoperative neurocognitive disorder).

Pharmacological Inhibition of PARP6 Triggers Multipolar Spindle Formation and Elicits Therapeutic Effects in Breast Cancer

: PARP proteins represent a class of post-translational modification enzymes with diverse cellular functions. Targeting PARPs has proven to be efficacious clinically, but exploration of the therapeutic potential of PARP inhibition has been limited to targeting poly(ADP-ribose) generating PARP, including PARP1/2/3 and tankyrases. The cancer-related functions of mono(ADP-ribose) generating PARP, including PARP6, remain largely uncharacterized. Here, we report a novel therapeutic strategy targeting PARP6 using the first reported PARP6 inhibitors. By screening a collection of PARP compounds for their ability to induce mitotic defects, we uncovered a robust correlation between PARP6 inhibition and induction of multipolar spindle (MPS) formation, which was phenocopied by PARP6 knockdown. Treatment with AZ0108, a PARP6 inhibitor with a favorable pharmacokinetic profile, potently induced the MPS phenotype, leading to apoptosis in a subset of breast cancer cells in vitro and antitumor effects in vivo. In addition, Chk1 was identified as a specific substrate of PARP6 and was further confirmed by enzymatic assays and by mass spectrometry. Furthermore, when modification of Chk1 was inhibited with AZ0108 in breast cancer cells, we observed marked upregulation of p-S345 Chk1 accompanied by defects in mitotic signaling. Together, these results establish proof-of-concept antitumor efficacy through PARP6 inhibition and highlight a novel function of PARP6 in maintaining centrosome integrity via direct ADP-ribosylation of Chk1 and modulation of its activity. SIGNIFICANCE: These findings describe a new inhibitor of PARP6 and identify a novel function of PARP6 in regulating activation of Chk1 in breast cancer cells.

Targeting the Warburg effect via LDHA inhibition engages ATF4 signaling for cancer cell survival

Nutrient restriction reprograms cellular signaling and metabolic network to shape cancer phenotype. Lactate dehydrogenase A (LDHA) has a key role in aerobic glycolysis (the Warburg effect) through regeneration of the electron acceptor NAD⁺ and is widely regarded as a desirable target for cancer therapeutics. However, the mechanisms of cellular response and adaptation to LDHA inhibition remain largely unknown. Here, we show that LDHA activity supports serine and aspartate biosynthesis. Surprisingly, however, LDHA inhibition fails to impact human melanoma cell proliferation, survival, or tumor growth. Reduced intracellular serine and aspartate following LDHA inhibition engage GCN2-ATF4 signaling to initiate an expansive pro-survival response. This includes the upregulation of glutamine transporter SLC1A5 and glutamine uptake, with concomitant build-up of essential amino acids, and mTORC1 activation, to ameliorate the effects of LDHA inhibition. Tumors with low LDHA expression and melanoma patients acquiring resistance to MAPK signaling inhibitors, which target the Warburg effect, exhibit altered metabolic gene expression reminiscent of the ATF4-mediated survival signaling. ATF4-controlled survival mechanisms conferring synthetic vulnerability to the approaches targeting the Warburg effect offer efficacious therapeutic strategies.

Spinal cord protection in aortic endovascular surgery

A persistent neurological deficit, such as paraplegia or paraparesis, secondary to spinal cord injury remains one of the most feared complications of surgery on the descending thoracic or abdominal aorta. This is despite sophisticated advances in imaging and the use of less invasive endovascular procedures. Extensive fenestrated endovascular aortic graft prostheses still carry a risk of spinal cord injury of up to 10%; thus, this risk should be identified and strategies implemented to protect the spinal cord and maintain perfusion. The patients at highest risk are those undergoing extensive thoracic aortic stenting including thoracic, abdominal, and pelvic vessels. Although many techniques are available, lumbar cerebrospinal fluid drainage remains the most frequent intervention, along with maintenance of perfusion pressure and possibly staged procedures to allow collateral vessel stabilization. Many questions remain regarding other technical aspects, spinal cord monitoring and cooling, pharmacological protection, and the optimal duration of interventions into the postoperative period.

Tobacco-induced suppression of the vascular response to dental plaque

Cigarette smoking presents oral health professionals with a clinical and research conundrum: reduced periodontal vascular responsiveness to the oral biofilm accompanied by increased susceptibility to destructive periodontal diseases. This presents a significant problem, hampering diagnosis and complicating treatment planning. The aim of this review is to summarize contemporary hypotheses that help to explain mechanistically the phenomenon of a suppressed bleeding response to dysbiotic plaque in the periodontia of smokers. The influence of smoke exposure on angiogenesis, innate cell function, the production of inflammatory mediators including cytokines and proteases, tobacco-bacteria interactions, and potential genetic predisposition are discussed.

Specific covalent inhibition of MALT1 paracaspase suppresses B cell lymphoma growth

The paracaspase MALT1 plays an essential role in activated B cell-like diffuse large B cell lymphoma (ABC DLBCL) downstream of B cell and TLR pathway genes mutated in these tumors. Although MALT1 is considered a compelling therapeutic target, the development of tractable and specific MALT1 protease inhibitors has thus far been elusive. Here, we developed a target engagement assay that provides a quantitative readout for specific MALT1-inhibitory effects in living cells. This enabled a structure-guided medicinal chemistry effort culminating in the discovery of pharmacologically tractable, irreversible substrate-mimetic compounds that bind the MALT1 active site. We confirmed that MALT1 targeting with compound 3 is effective at suppressing ABC DLBCL cells in vitro and in vivo. We show that a reduction in serum IL-10 levels exquisitely correlates with the drug pharmacokinetics and degree of MALT1 inhibition in vitro and in vivo and could constitute a useful pharmacodynamic biomarker to evaluate these compounds in clinical trials. Compound 3 revealed insights into the biology of MALT1 in ABC DLBCL, such as the role of MALT1 in driving JAK/STAT signaling and suppressing the type I IFN response and MHC class II expression, suggesting that MALT1 inhibition could prime lymphomas for immune recognition by cytotoxic immune cells.

Abstract 2916: Targeting lysophospholipid metabolism inhibits pancreatic cancer cell proliferation under nutrient-limiting conditions

Patients with pancreatic ductal adenocarcinoma (PDAC) have a poor prognosis, and more effective systemic treatments for patients with local progression or metastasis (85% of cases) are needed. The pancreatic tumor microenvironment provides a rich source for novel drug targets. We aimed to identify and validate novel metabolic drug targets that are unique to hypoxic PDAC cells. Using bulk RNA sequencing in combination with metabolomics analyses in vitro, we previously found that PDAC cells negate the loss of intracellular unsaturated fatty acids in hypoxia by orchestrating the release of lysophospholipids (lyso-PLs) by cancer-associated fibroblasts, which are then taken up and stored in intracellular lipid droplets in hypoxic cancer cells. To confirm the relevance of these findings in vivo, we performed 3' droplet based single-cell RNA sequencing (scRNA-seq) combined with metabolomics analyses of intracellular and extracellular (tumor interstitial fluid) metabolites of MIAPaCa2 and patient-derived xenografts (PDX). Identification of cell lineages and subpopulations with hypoxic gene signatures was performed to correlate changes in metabolite levels with metabolic gene expression in vivo. This approach confirmed differential expression of lipid droplet-associated enzymes in hypoxic areas of the tumor, including lyso-PL acyl transferases (LPCAT1, LPCAT3), and phospholipases (LYPLA1, PLA2G15). We found that resistance of PDAC cell lines to pharmacologic treatment with inhibitors of fatty acid desaturases (FADS), reminiscent of hypoxia and nutrient starvation in vivo, was mediated by uptake of lyso-PLs from the medium. Importantly, genetic knockdown of LPCAT and LYPLA isoforms reversed the resistance to FADS inhibitors in culture in vitro and in vivo. Clinical relevance was demonstrated by mRNA expression analysis of PDAC patients from The Cancer Genome Atlas (TCGA) database, which showed that the expression of lyso-PL metabolizing genes is correlated with a significant worse prognosis (log-rank test, P=0.008). We are currently developing pharmacologic approaches to target LPCAT and LYPLA enzymes in hypoxic cancer cells as a novel approach for PDAC patients with unresectable disease.

Citation Format: Petrus R. de Jong, Marco Maruggi, Alejandro D. Campos, Morgan A. Brand, Robert Lemos, David A. Scott, Sally A. Litherland, J. Pablo Arnoletti, Brian P. James, Garth Powis. Targeting lysophospholipid metabolism inhibits pancreatic cancer cell proliferation under nutrient-limiting conditions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2916.

Recommendations for the nomenclature of cognitive change associated with anaesthesia and surgery-2018

Cognitive change affecting patients after anaesthesia and surgery has been recognised for more than 100 yr. Research into cognitive change after anaesthesia and surgery accelerated in the 1980s when multiple studies utilised detailed neuropsychological testing for assessment of cognitive change after cardiac surgery. This body of work consistently documented decline in cognitive function in elderly patients after anaesthesia and surgery, and cognitive changes have been identified up to 7.5 yr afterwards. Importantly, other studies have identified that the incidence of cognitive change is similar after non-cardiac surgery. Other than the inclusion of non-surgical control groups to calculate postoperative cognitive dysfunction, research into these cognitive changes in the perioperative period has been undertaken in isolation from cognitive studies in the general population. The aim of this work is to develop similar terminology to that used in cognitive classifications of the general population for use in investigations of cognitive changes after anaesthesia and surgery. A multispecialty working group followed a modified Delphi procedure with no prespecified number of rounds comprised of three face-to-face meetings followed by online editing of draft versions. Two major classification guidelines [Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5) and National Institute for Aging and the Alzheimer Association (NIA-AA)] are used outside of anaesthesia and surgery, and may be useful for inclusion of biomarkers in research. For clinical purposes, it is recommended to use the DSM-5 nomenclature. The working group recommends that 'perioperative neurocognitive disorders' be used as an overarching term for cognitive impairment identified in the preoperative or postoperative period. This includes cognitive decline diagnosed before operation (described as neurocognitive disorder); any form of acute event (postoperative delirium) and cognitive decline diagnosed up to 30 days after the procedure (delayed neurocognitive recovery) and up to 12 months (postoperative neurocognitive disorder).

Erratum: Three New Low-Energy Resonances in the ^{22}Ne(p,γ)^{23}Na Reaction [Phys. Rev. Lett. 115, 252501 (2015)]

This corrects the article DOI: 10.1103/PhysRevLett.115.252501.

Cas13d Is a Compact RNA-Targeting Type VI CRISPR Effector Positively Modulated by a WYL-Domain-Containing Accessory Protein

Bacterial class 2 CRISPR-Cas systems utilize a single RNA-guided protein effector to mitigate viral infection. We aggregated genomic data from multiple sources and constructed an expanded database of predicted class 2 CRISPR-Cas systems. A search for novel RNA-targeting systems identified subtype VI-D, encoding dual HEPN domain-containing Cas13d effectors and putative WYL-domain-containing accessory proteins (WYL1 and WYL-b1 through WYL-b5). The median size of Cas13d proteins is 190 to 300 aa smaller than that of Cas13a-Cas13c. Despite their small size, Cas13d orthologs from Eubacterium siraeum (Es) and Ruminococcus sp. (Rsp) are active in both CRISPR RNA processing and targeting, as well as collateral RNA cleavage, with no target-flanking sequence requirements. The RspWYL1 protein stimulates RNA cleavage by both EsCas13d and RspCas13d, demonstrating a common regulatory mechanism for divergent Cas13d orthologs. The small size, minimal targeting constraints, and modular regulation of Cas13d effectors further expands the CRISPR toolkit for RNA manipulation and detection.

Cognitive Function Before and After Left Heart Catheterization

BACKGROUND

Hospital procedures have been associated with cognitive change in older patients. This study aimed to document the prevalence of mild cognitive impairment in individuals undergoing left heart catheterization (LHC) before the procedure and the incidence of cognitive decline to 3 months afterwards.

METHODS AND RESULTS

We conducted a prospective, observational, clinical investigation of elderly participants undergoing elective LHC. Cognition was assessed using a battery of written tests and a computerized cognitive battery before the LHC and then at 3 months afterwards. The computerized tests were also administered at 24 hours (or discharge) and 7 days after LHC. A control group of 51 community participants was recruited to calculate cognitive decline using the Reliable Change Index. Of 437 participants, mild cognitive impairment was identified in 226 (51.7%) before the procedure. Computerized tests detected an incidence of cognitive decline of 10.0% at 24 hours and 7.5% at 7 days. At 3 months, written tests detected an incidence of cognitive decline of 13.1% and computerized tests detected an incidence of 8.5%. Cognitive decline at 3 months using written tests was associated with increasing age, whereas computerized tests showed cognitive decline was associated with baseline amnestic mild cognitive impairment, diabetes mellitus, and prior coronary stenting.

CONCLUSIONS

More than half the patients aged >60 years presenting for LHC have mild cognitive impairment. LHC is followed by cognitive decline in 8% to 13% of individuals at 3 months after the procedure. Subtle cognitive decline both before and after LHC is common and may have important clinical implications.

CLINICAL TRIAL REGISTRATION INFORMATION

URL: www.anzctr.org.au. Unique identifier: ACTRN12607000051448.

Prediction of enzymatic pathways by integrative pathway mapping

The functions of most proteins are yet to be determined. The function of an enzyme is often defined by its interacting partners, including its substrate and product, and its role in larger metabolic networks. Here, we describe a computational method that predicts the functions of orphan enzymes by organizing them into a linear metabolic pathway. Given candidate enzyme and metabolite pathway members, this aim is achieved by finding those pathways that satisfy structural and network restraints implied by varied input information, including that from virtual screening, chemoinformatics, genomic context analysis, and ligand -binding experiments. We demonstrate this integrative pathway mapping method by predicting the L-gulonate catabolic pathway in Haemophilus influenzae Rd KW20. The prediction was subsequently validated experimentally by enzymology, crystallography, and metabolomics. Integrative pathway mapping by satisfaction of structural and network restraints is extensible to molecular networks in general and thus formally bridges the gap between structural biology and systems biology.

Hepatic GALE Regulates Whole-Body Glucose Homeostasis by Modulating Tff3 Expression

Transcripts of key enzymes in the Leloir pathway of galactose metabolism in mouse livers are significantly increased after chronic high-fat/high-sucrose feeding. UDP-galactose-4-epimerase (GALE) is the last enzyme in this pathway that converts UDP-galactose to UDP-glucose and was previously identified as a downstream target of the endoplasmic reticulum (ER) stress effector spliced X-box binding protein 1, suggesting an interesting cross talk between galactose and glucose metabolism in the context of hepatic ER stress and whole-body metabolic fitness. However, its specific role in glucose metabolism is not established. Using an inducible and tissue-specific mouse model, we report that hepatic overexpression of Gale increases gluconeogenesis from pyruvate and impairs glucose tolerance. Conversely, genetic reduction of Gale in liver improves glucose tolerance. Transcriptional profiling identifies trefoil factor 3 (Tff3) as one of the downstream targets of GALE. Restoration of Tff3 expression corrects glucose intolerance in Gale-overexpressing mice. These studies reveal a new link between hepatic GALE activity and whole-body glucose homeostasis via regulation of hepatic Tff3 expression.