Devaluation of response-produced safety signals reveals circuits for goal-directed versus habitual avoidance in dorsal striatum.

Active avoidance responses (ARs) are instrumental behaviors that prevent harm. Adaptive ARs may contribute to active coping, whereas maladaptive avoidance habits are implicated in anxiety and obsessive-compulsive disorders. The AR learning mechanism has remained elusive, as successful avoidance trials produce no obvious reinforcer. We used a novel outcome-devaluation procedure in rats to show that ARs are positively reinforced by response-produced feedback (FB) cues that develop into safety signals during training. Males were sensitive to FB-devaluation after moderate training, but not overtraining, consistent with a transition from goal-directed to habitual avoidance. Using chemogenetics and FB-devaluation, we also show that goal-directed vs. habitual ARs depend on dorsomedial vs. dorsolateral striatum, suggesting a significant overlap between the mechanisms of avoidance and rewarded instrumental behavior. Females were insensitive to FB-devaluation due to a remarkable context-dependence of counterconditioning. However, degrading the AR-FB contingency suggests that both sexes rely on safety signals to perform goal-directed ARs.

Stabilizing Pseudouridimycin: Synthesis, RNA Polymerase Inhibitory Activity, and Antibacterial Activity of Dipeptide-Modified Analogues.

Pseudouridimycin (PUM) is a microbially produced C-nucleoside dipeptide that selectively targets the nucleotide addition site of bacterial RNA polymerase (RNAP) and that has a lower rate of spontaneous resistance emergence relative to current drugs that target RNAP. Despite its promising biological profile, PUM undergoes relatively rapid decomposition in buffered aqueous solutions. Here, we describe the synthesis, RNAP-inhibitory activity, and antibacterial activity of chemically stabilized analogues of PUM. These analogues feature targeted modifications that mitigate guanidine-mediated hydroxamate bond scission. A subset of analogues in which the central hydroxamate is replaced with amide or hydrazide isosteres retain the antibacterial activity of the natural product.

Beyond Fear, Extinction, and Freezing: Strategies for Improving the Translational Value of Animal Conditioning Research.

Translational neuroscience for anxiety has had limited success despite great progress in understanding the neurobiology of Pavlovian fear conditioning and extinction. This chapter explores the idea that conditioning paradigms have had a modest impact on translation because studies in animals and humans are misaligned in important ways. For instance, animal conditioning studies typically use imminent threats to assess short-duration fear states with single behavioral measures (e.g., freezing), whereas human studies typically assess weaker or more prolonged anxiety states with physiological (e.g., skin conductance) and self-report measures. A path forward may be more animal research on conditioned anxiety phenomena measuring dynamic behavioral and physiological responses in more complex environments. Exploring transitions between defensive brain states during extinction, looming threats, and post-threat recovery may be particularly informative. If care is taken to align paradigms, threat levels, and measures, this strategy may reveal stable patterns of non-conscious defense in animals and humans that correlate better with conscious anxiety. This shift in focus is also warranted because anxiety is a bigger problem than fear, even in disorders defined by dysfunctional fear or panic reactions.

Persistent up-regulation of polyribosomes at synapses during long-term memory, reconsolidation, and extinction of associative memory.

Local protein synthesis at synapses can provide a rapid supply of proteins to support synaptic changes during consolidation of new memories, but its role in the maintenance or updating of established memories is unknown. Consolidation requires new protein synthesis in the period immediately following learning, whereas established memories are resistant to protein synthesis inhibitors. We have previously reported that polyribosomes are up-regulated in the lateral amygdala (LA) during consolidation of aversive-cued Pavlovian conditioning. In this study, we used serial section electron microscopy reconstructions to determine whether the distribution of dendritic polyribosomes returns to baseline during the long-term memory phase. Relative to control groups, long-term memory was associated with up-regulation of polyribosomes throughout dendrites, including in dendritic spines of all sizes. Retrieval of a consolidated memory by presentation of a small number of cues induces a new, transient requirement for protein synthesis to maintain the memory, while presentation of a large number of cues results in extinction learning, forming a new memory. One hour after retrieval or extinction training, the distribution of dendritic polyribosomes was similar except in the smallest spines, which had more polyribosomes in the extinction group. Our results demonstrate that the effects of learning on dendritic polyribosomes are not restricted to the transient translation-dependent phase of memory formation. Cued Pavlovian conditioning induces persistent synapse strengthening in the LA that is not reversed by retrieval or extinction, and dendritic polyribosomes may therefore correlate generally with synapse strength as opposed to recent activity or transient translational processes.

IRE-1-Targeting Caged Prodrug with Endoplasmic Reticulum Stress-Inducing and XBP-1S-Inhibiting Activities for Cancer Therapy.

Activation of the IRE-1/XBP-1s pathway supports tumor progression. Here, we report a novel prodrug, TC-D-F07, in which a thiol-reactive dinitrobenzenesulfonyl (Dns) cage was installed onto the C8 hydroxyl of the covalent IRE-1 inhibitor D-F07. The electron-withdrawing Dns group in TC-D-F07 stabilizes the neighboring 1,3-dioxane acetal, allowing for stimulus-mediated control of its inhibitory activity. TC-D-F07 exhibits high sensitivity to intracellular thiols. Because tumor cells exhibit higher concentrations of glutathione and cysteine, treatment with TC-D-F07 results in more sustained levels of D-F07 in transformed versus normal cells. In addition, we show that a dinitrophenyl cysteine adduct resulting from cleavage of the Dns group induces endoplasmic reticulum (ER) stress, causing tumor cells to increase the expression of XBP-1s. The accumulated levels of D-F07 and its gradual decomposition into the active IRE-1 inhibitor eventually deprive tumor cells of XBP-1s, leading to more severe apoptosis than those treated with its uncaged analogue.

Correction: Total synthesis and chemical stability of pseudouridimycin.

Correction for 'Total synthesis and chemical stability of pseudouridimycin' by Christopher F. Cain et al., Chem. Commun., 2022, DOI: 10.1039/d1cc07059b.

Total synthesis and chemical stability of pseudouridimycin.

We report the chemical synthesis of pseudouridimycin (1), an antimicrobial natural product that potently and selectively inhibits bacterial RNA polymerase. Chemical stability studies revealed intramolecular hydroxamate bond scission to be a major decomposition pathway for 1 in aqueous buffer. Replacement of the hydroxamate bond with a tertiary amide, as in 16, afforded a conformational isostere resistant to degradation. These studies pave the way for the design and synthesis of analogues with improved chemical stability and biological activity.

Conformal Left Atrial Appendage Seal Device for Left Atrial Appendage Closure: First Clinical Use.

OBJECTIVES: The authors report the first clinical experience with the Conformal Left Atrial Appendage Seal (CLAAS) device. BACKGROUND: The CLAAS device was designed to address the limitations of first-generation left atrial appendage closure (LAAC) devices by providing an implant that is minimally traumatic, can be deployed in a noncoaxial fashion, and does not require postprocedural oral anticoagulation. METHODS: Patients with atrial fibrillation at high stroke risk (CHA2DS2-VASc score ≥2) were recruited using standard selection criteria. The LAAC procedure was guided by transesophageal echocardiography with patients under general anesthesia. The CLAAS device is composed of a foam cup, with a Nitinol endoskeleton with an expanded polytetrafluoroethylene cover, delivered with a standard delivery system using a tether for full recapture. All patients received dual-antiplatelet therapy for 6 months, followed by aspirin alone. Transesophageal echocardiographic follow-up was scheduled for 45 days and 1 year. RESULTS: Twenty-two patients (63.7% with CHA2DS2-VASc scores ≥3, 76.2% with HAS-BLED scores ≥3) were enrolled. The device was successfully implanted in 18 patients and unsuccessfully in 4 patients. There were no serious procedural complications. On transesophageal echocardiography performed at 45 days, 1 significant leak (≥5 mm) was seen, which was due to a large posterior lobe not appreciated at the time of implantation, and 1 device-related thrombus was noted, which resolved on oral anticoagulation. There were no periprocedural strokes, major pericardial effusions, or systemic or device embolization. CONCLUSIONS: This first-in-human study demonstrates the clinical feasibility of the CLAAS device for LAAC.

Preclinical Assessment of a Novel Conformable Foam-Based Left Atrial Appendage Closure Device.

BACKGROUND: Left atrial appendage (LAA) occlusion has been established as an alternative to systemic anticoagulation for stroke prevention in patients with atrial fibrillation; however, limitations of current devices have slowed adoption. We present preclinical evaluations of a novel device, the Conformal Left Atrial Appendage Seal (CLAAS). METHODS: An in vitro assessment of conformability was conducted to evaluate the two CLAAS devices (regular 27 mm and large 35 mm) and a Watchman 2.5 (27 mm). Devices were placed within silicone tubes and compressed in a vise submerged in a water bath at 37°C. Changes in device diameter and visual seal were noted. Acute (n = 1) and chronic 60-day (n = 6) canine studies with gross and histologic assessment were performed. RESULTS: Conformability bench tests demonstrated that the regular CLAAS implant was able to seal oval orifices from 20 × 30 mm to 15 × 33 mm and the large from 30 × 35 mm to 20 × 40 mm. As the CLAAS implant was compressed in the minor diameter, it increased in the major diameter, thereby filling the oval space, whereas the Watchman 2.5 showed gaps and maintained its round configuration when compressed in one direction. Seven devices were successfully implanted in the canine model with complete seal without thrombus. Histologic examination showed complete neointima covering with minimal inflammation at 60 days. CONCLUSIONS: Preclinical testing demonstrated the conformability of the CLAAS implant and its ability to seal the LAA. Clinical studies are ongoing to characterize the utility of the CLAAS implant in the treatment of patients with atrial fibrillation.

Postoperative pelvic incidence (PI) change may impact sagittal spinopelvic alignment (SSA) after instrumented surgical correction of adult spine deformity (ASD).

OBJECTIVES: To study factors causing postoperative change of PI after surgical correction of ASD and to assess the effect of this variability on postoperative PI-LL mismatch. BACKGROUND: PI is used as an individual constant to define lumbar lordosis (LL) correction goal (PI-LL < 10). Postoperative changes of PI were shown but with opposite vectors. The impact of the PI variability on the postoperative PI-LL has not been studied. METHODS: The medical and radiographic data analyzed for patients who underwent long posterior instrumented spinal fusion. Inclusion criteria are age, ≥ 20 years old; ASD due to degenerative disk disease (DDD) or scoliosis (DS); ≥ 3 levels fused; and 2-year follow-up or revision. Studied parameters are LL (L1-S1), PI, sacral slope (SS), pelvic tilt (PT), and PI-LL. Measurement error and postoperative changes were defined. Statistical analysis includes ANOVA, correlation, regression, and risk assessment by odds ratio; P ≤ 0.05 considered statistically significant. RESULTS: Eighty patients were included: mean age, 62.4 years-old (SD, 11.1); female, 63.7%; mean body mass index (BMI), 27.1 (SD, 5.6). Distribution of patients by follow-ups includes preoperative 100%; postoperative (1-3 weeks), 100%; 11-13 months. 90%; 22-26 months, 58%; and revision: 24%. Pre- versus postoperative PI (∆PI) changed both positively and negatively and the absolute value of change|∆PI| exceeded measurement error (P ≤ 0.05) reaching as high as 31°, and progressed with time; R2 dropped from 0.73 to 0.45 (P < 0.001); ∆PI depended on disproportional changes of SS and PT, preoperative PI, and change of LL. Obesity, DS, and absence of sacroiliac fixation increased |∆PI|. The risk of LL insufficient correction (PI-LL > 10°) associated with a |∆PI|> 6°, P = 0.05. Sacroiliac fixation diminished PI variability only during the first postoperative year. CONCLUSION: Preoperative variability and postoperative instability of PI diminish the applicability of the PI-LL < 10° goal to plan correction of LL. An alternative method is offered. LEVEL OF EVIDENCE: IV.

Development of Tumor-Targeting IRE-1 Inhibitors for B-cell Cancer Therapy.

The IRE-1 kinase/RNase splices the mRNA of the XBP-1 gene, resulting in the spliced XBP-1 (XBP-1s) mRNA that encodes the functional XBP-1s transcription factor that is critically important for the growth and survival of B-cell leukemia, lymphoma, and multiple myeloma (MM). Several inhibitors targeting the expression of XBP-1s have been reported; however, the cytotoxicity exerted by each inhibitor against cancer cells is highly variable. To design better therapeutic strategies for B-cell cancer, we systematically compared the ability of these compounds to inhibit the RNase activity of IRE-1 in vitro and to suppress the expression of XBP-1s in mouse and human MM cell lines. Tricyclic chromenone-based inhibitors B-I09 and D-F07, prodrugs harboring an aldehyde-masking group, emerged as the most reliable inhibitors for potent suppression of XBP-1s expression in MM cells. The cytotoxicity of B-I09 and D-F07 against MM as well as chronic lymphocytic leukemia and mantle cell lymphoma could be further enhanced by combination with inhibitors of the PI3K/AKT pathway. Because chemical modifications of the salicylaldehyde hydroxy group could be used to tune 1,3-dioxane prodrug stability, we installed reactive oxygen species-sensitive structural cage groups onto these inhibitors to achieve stimuli-responsive activities and improve tumor-targeting efficiency.

Context- and Subgroup-Specific Language Changes in Individuals Who Develop PTSD After Trauma.

Post-traumatic stress disorder (PTSD) is a very common condition with more than 3 million new cases per year in the US alone. The right diagnosis in a timely manner is key to ensuring a prompt treatment that could lead to a full recovery. Unfortunately, avoidance of trauma reminders, social stigma, self-presentation, and self-assessment biases often prevent individuals from seeking timely evaluation, leading to delays in treatment and suboptimal outcomes. Previous studies show that various mental health conditions are associated with distinct patterns of language use. Analyzing language use may also help to avoid response bias in self-reports. In this study, we analyze text data from online forum users, showing that language use differences between PTSD sufferers and controls. In all groups of PTSD sufferers, the usage of singular first-person pronouns was higher and that of plural first-person pronouns was lower than in control groups. However, the analysis of other word categories suggests that subgroups of people with the same mental health disorder (here PTSD) may have salient differences in their language use, particularly in word usage frequencies. Additionally, we show that word usage patterns may vary depending on the type of the text analyzed. Nevertheless, more studies will be needed to increase precision by further examine a variety of text types and different comorbidities. If properly developed, such tools may facilitate earlier PTSD diagnosis, leading to timely support and treatment, which are associated with better outcomes.

Reducing shock imminence eliminates poor avoidance in rats.

In signaled active avoidance (SigAA), rats learn to suppress Pavlovian freezing and emit actions to remove threats and prevent footshocks. SigAA is critical for understanding aversively motivated instrumental behavior and anxiety-related active coping. However, with standard protocols ∼25% of rats exhibit high freezing and poor avoidance. This has dampened enthusiasm for the paradigm and stalled progress. We demonstrate that reducing shock imminence with long-duration warning signals leads to greater freezing suppression and perfect avoidance in all subjects. This suggests that instrumental SigAA mechanisms evolved to cope with distant harm and protocols that promote inflexible Pavlovian reactions are poorly designed to study avoidance.

Strap stabilization for proximal junctional kyphosis prevention in instrumented posterior spinal fusion.

STUDY DESIGN: This is a retrospective, single-institution, cohort study. OBJECTIVES: To evaluate the association of Mersilene tape use and risk of proximal junctional kyphosis (PJK), after surgical correction of adult spinal deformity (ASD) by posterior instrumented fusion (PIF). PJK, following long spinal PIF, is a complication which often requires reoperation. Mersilene tape, strap stabilization of the supra-adjacent level to upper instrumented vertebra (UIV) seems a preventive measure. METHODS: Patients who underwent PIF for ASD with Mersilene tape stabilization (case group) or without (control group) between 2006 and 2016 were analyzed preoperatively to 2-year follow-up. Matching of potential controls to each case was performed. Radiographic sagittal Cobb angle (SCA), lumbar lordosis, pelvic tilt, sacral slope, and pelvic incidence were measured pre- and postoperatively, using a deformity measuring software program. PJK was defined as progression of postoperative junctional SCA at UIV ≥ 10°. RESULTS: Eighty patients were included: 20 cases and 60 controls. The cumulative rate of PJK ≥ 10° at 2-year follow-up was 15% in cases versus 38% of controls (OR = 0.28; P = 0.04) with higher latent period in cases, (20 vs. 7.5 months), P = 0.018. Mersilene tape decreased risk of PJK linked with the impact of the following confounders: age, ≥ 55 years old (OR = 0.19; 0.02 ≥ P ≤ 0.03); number of spinal levels fused 7-15 (OR = 0.13; 0.02 ≥ P ≤ 0.06); thoracic UIV (T12-T1) (OR = 0.13; 0.02 ≥ P ≤ 0.06); BMI ≥ 27 kg/m2 (OR = 0.22; 0.03 ≥ P ≤ 0.08); and osteoporosis (OR = 0.13; 0.02 ≥ P ≤ 0.08). CONCLUSIONS: Mersilene tape at UIV + 1 level decreases the risk of PJK following PIF for ASD. These slides can be retrieved under Electronic Supplementary Material.

Corrosion of Titanium Spinal Explants Is Similar to That Observed in Oil Field Line Pipe Steel: Evidence of Microbial-Influenced Corrosion In Vivo.

Current explanations of biomedical alloy degradation are focused on the physicochemical mechanisms of galvanic, pitting, crevice, and fretting corrosion. Ultimately, these studies dismiss the corrosion mechanism as a function of the local microbiome. Sixty spine hardware constructs were examined immediately after explantation for biofilm formation. Marked rod sections were imaged using scanning electron microscopy with energy dispersive x-ray spectroscopy. Backscatter mode was employed to better image the topology of the surface. There is clear differentiation between discoloration due to corrosion vs mechanical damage. Under scanning electron microscopy backscatter electron shadow examination, the authors noted that not all biofilm was removed using the surgical wipes. Corrosion pits were noticeably larger and numerous in areas of biofilm. In areas not associated with biofilms, there were few pits even if mechanical wear was evident. There is no evidence that the surface corrosion is modified between clinically diagnosed infected and noninfected patients. The surface damage present on explanted Ti6Al4V spine rods is uniquely similar to damage found in other industries where microbial-influenced corrosion is prevalent. Given that similar anaerobic, sulfur-reducing bacteria reside in and on human tissues, it is most likely that corrosion observed on explanted hardware is the result of microbial-influenced corrosion and not from inflammatory or other processes. Using analysis methods from other industries to characterize the microbiome present on explanted hardware is necessary. In so doing, a new definition of hardware-induced infection will be forthcoming. [Orthopedics. 2020;43(1):62-67.].

Synthesis of Enantiopure ε-Oxapipecolic Acid.

A six-step synthesis of orthogonally protected (S)-ε-oxapipecolic acid is described, starting from a commercially available glutamate diester. The approach features mCPBA-mediated amine oxidation and an intramolecular Mitsunobu reaction to form the tetrahydrooxazine ring. The enantiopure building block was employed in the synthesis of a short model peptide to determine the amide rotamer preference N-terminal to the cyclic residue. In contrast to pipecolic acid, which exhibits a high cis amide population, the ε heteroatom in oxapipecolic acid exerts a strong trans substantiating effect through lone pair repulsion.

Long-Term Treatment Effect and Predictability of Spinopelvic Alignment After Surgical Correction of Adult Spine Deformity With Patient-Specific Spine Rods.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To evaluate the short- and long-term treatment effect (TE) of spinopelvic parameters after surgical correction of adult spine deformity (ASD) utilizing preoperative planning and patient-specific spine rods (PSSRs), and to assess the correspondence between planned and real outcomes. SUMMARY OF BACKGROUND DATA: PSSR have been used in ASD correction for the last decade. However, a TE and predictability of spinopelvic alignment at long-term follow-up has not been studied. METHODS: Inclusion criteria: male or female; age more than 20 years; correction of ASD with PSSR; 24-month follow-up (or revision surgery). Studied parameters: sagittal vertical axis; lumbar lordosis (LL); pelvic tilt (PT); sacral slope; pelvic incidence (PI); and PI-LL. The measurement error, TE (the differences between postoperative and preoperative values), standardized TE, and predictability of the studied parameters assessed. The variables included categorical (optimal/nonoptimal) and continuous obtained by direct measurements and weighted by individual optimal values. Statistical significance was set at P ≤ 0.05. RESULTS: Thirty-four patients were included: 56% women; the mean age, 63.4 (standard deviation, 12.7); at each follow-up: 32 at 1 to 3 months, 34 at 11 to 13, and 14 at 23 to 25 with 9 followed to the revision surgery. Strong or moderate TE was shown for sagittal vertical axis, LL, and PI-LL. The TE of PT and sacral slope was less significant and lower than planned. PI was not stable in 18%. The changes of continuous variables were more prominent and statistically significant then categorical. The mean values did not show significant differences between planned and postoperative outcomes except for PT. However, the individual deviations were substantial for all parameters. Significant predictability was shown only for LL and PI. CONCLUSION: Use of PSSR showed strong and relatively stable TE in ASD during 2 postoperative years. However, improvement of the planning accuracy may contribute to further enhancement of the method's efficacy. LEVEL OF EVIDENCE: 4.

Structural Tailoring of a Novel Fluorescent IRE-1 RNase Inhibitor to Precisely Control Its Activity.

Activation of the IRE-1/XBP-1 pathway has been linked to many human diseases. We report a novel fluorescent tricyclic chromenone inhibitor, D-F07, in which we incorporated a 9-methoxy group onto the chromenone core to enhance its potency and masked the aldehyde to achieve long-term efficacy. Protection of the aldehyde as a 1,3-dioxane acetal led to strong fluorescence emitted by the coumarin chromophore, enabling D-F07 to be tracked inside the cell. We installed a photolabile structural cage on the hydroxy group of D-F07 to generate PC-D-F07. Such a modification significantly stabilized the 1,3-dioxane acetal protecting group, allowing for specific stimulus-mediated control of inhibitory activity. Upon photoactivation, the re-exposed hydroxy group on D-F07 triggered the aldehyde-protecting 1,3-dioxane acetal to slowly decompose, leading to the inhibition of the RNase activity of IRE-1. Our novel findings will also allow for spatiotemporal control of the inhibitory effect of other salicylaldehyde-based compounds currently in development.

Avoidance Problems Reconsidered.

Active avoidance is the prototypical paradigm for studying aversively-motivated instrumental behavior. However, avoidance research stalled amid heated theoretical debates and the hypothesis that active avoidance is essentially Pavlovian flight. Here I reconsider key "avoidance problems" and review neurobehavioral data collected with modern tools. Although the picture remains incomplete, these studies strongly suggest that avoidance has an instrumental component and is mediated by brain circuits that resemble appetitive instrumental actions more than Pavlovian fear reactions. Rapid progress may be possible if investigators consider important factors like safety signals, response-competition, goal-directed vs. habitual control and threat imminence in avoidance study design. Since avoidance responses likely contribute to active coping, this research has important implications for understanding human resilience and disorders of control.