Reversible Impairment Research Articles

Early-life exposure to methylmercury induces reversible behavioral impairments and gene expression modifications in one isogenic lineage of mangrove rivulus fish Kryptolebias marmoratus

Methylmercury (MeHg) is a ubiquitous bioaccumulative neurotoxicant present in aquatic ecosystems. It is known to alter behaviors, sensory functions and learning abilities in fish and other vertebrates. Developmental and early-life stages exposure to MeHg can lead to brain damage with immediate consequences on larvae behavior, but may also induce long term effects in adults after a detoxification period. However, very little is known about developmental origin of behavioral impairment in adults due to early exposure to MeHg. The aim of this study is to assess whether early-life MeHg exposure induces immediate and/or delayed effects on behaviors, related genes expression and DNA methylation (one of epigenetic mechanisms). To reach this goal, newly hatched larvae of mangrove rivulus fish, Kryptolebias marmoratus, were exposed to two sub-lethal concentrations of MeHg (90 μg/L and 135 µg/L) for 7 days, and immediate and delayed effects were assessed respectively in 7 dph (days post-hatching) and 90 dph fish. This species naturally produces isogenic lineages due to its self-fertilizing reproduction system, which is unique among vertebrates. It allows to study how environment stressors can influence organism's phenotype while minimizing genetic variability. As results, both MeHg exposures are associated with a decreased foraging efficiency and thigmotaxis, and a dose-dependent reduction in larvae locomotor activity. Regarding molecular analysis in larvae whole bodies, both MeHg exposures induced significant decreased expression of DNMT3a, MAOA, MeCP2 and NIPBL, and significant increase of GSS, but none of those genes underwent methylation changes in targeted CpGs. None of significant behavioral and molecular impairments observed in 7-dph larvae were found in 90-dph adults, which highlight a distinction between immediate and delayed effects of developmental MeHg exposure. Our results suggest implications of aminergic system and its neurotransmitters, redox/methylation trade-off and possibly other epigenetic mechanisms in MeHg neurotoxicity underlying behavioral alterations in rivulus.

Reversal of chronic restraint stress-induced memory impairment by Japanese sake yeast supplement in mice: Role of adenosine A1 and A2A receptors

Controversial studies indicate the adenosine compound (a neuromodulator with neuroprotective activity) intervention on cognitive performance. On the other hand, Japanese sake yeast has been enriched with oral adenosine analogs as a novel natural agent. As the first report, we aimed to evaluate the effects of Japanese sake yeast supplement in a mouse model of chronic restraint stress-induced cognitive dysfunction. Mice were subjected to a one-week stress protocol and concomitantly treated orally with sake yeast at the dose level of 100, 200 and 300 mg/kg once daily for a week. The spatial and conditioned fear memory functions were evaluated with the Morris Water Maze (MWM) and the Passive Avoidance Learning (PAL) test, respectively. In all dosing regimens, improvements in spatial cognition were observed significantly in the MWM. 200 and 300 mg/kg of sake yeast significantly improved short- and long-term fear memory functions in the PAL test. Memory-enhancing effect of sake yeast was potentiated by the injection of ZM241385 (15 mg/kg), a selective adenosine A2A receptor (A2AR) antagonist, but completely disappeared by the injection of 8-cyclopentyltheophylline (CPT-8, 10 mg/kg), a selective adenosine A1 receptor (A1R) antagonist. The findings of the present study demonstrate the efficacy of sake yeast in acting as a cognitive performance-enhancing agent. Eventually, sake yeast and its ingredient S-adenosyl methionine (SAM) may be useful in improving memory in patients suffering from many dementia forms including Alzheimer's disease (AD).

Neuroprotective Effect of Methanolic Ajwa Seed Extract on Lipopolysaccharide-Induced Memory Dysfunction and Neuroinflammation: In Vivo, Molecular Docking and Dynamics Studies.

Islamic literature has indicated that daily consumption of Ajwa dates heals a variety of chronic diseases and disorders. The current research investigates the neuroprotective effect of methanolic Ajwa seed extract (MASE) on lipopolysaccharide (LPS)-induced cognitive deficits using multiple approaches. For animal studies, MASE (200 and 400 mg/kg, p.o.) was administrated for thirty consecutive days, and four doses of LPS (250 µg/kg, i.p.) were injected to induce neurotoxicity. Memory functions were evaluated using elevated plus-maze and novel object recognition tests. Acetylcholine (ACh) and neuroinflammatory markers (cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and transforming growth factor (TGF)-β1) were estimated in brain tissues. Studies of molecular docking and dynamics were conducted to provide insight into the molecular-level mechanisms. MASE administration resulted in a significant reversal of LPS-induced memory impairment in both maze models. Both doses of MASE elevated the ACh levels in an LPS-treated rat brain. In addition, the extract lowered COX-2 and proinflammatory cytokines (TNF-α and IL-6) while increasing anti-inflammatory cytokines (IL-10 and TGF-β1) in LPS-treated brain tissues. Molecular modeling results revealed that the compound's ellagic acid, epicatechin, catechin, kaempferol, quercetin, and apigenin have the potential to act as a dual inhibitor of acetylcholinesterase (AChE) and COX-2 and can be responsible for the improvement of both cholinergic and inflammatory conditions, while the cinnamic acid, hesperidin, hesperetin, narengin, and rutin compounds are responsible only for the improvement of cholinergic transmission. The above compounds acted by interacting with the key residues Trp84, Asp72, Gly118, Ser200, Tyr334, and His440, which are responsible for the hydrolysis of ACh in AChE, while the COX-2 is inhibited by interacting with the residues (Val349, Leu352, Tyr355, Tyr385, Ala527, Ser530, and Leu531) of the hydrophobic channel. By promoting cholinergic activity and protecting neuroinflammation in the rat brain, MASE provides neuroprotection against LPS-induced cognitive deficits. Our preliminary findings will help with further drug discovery processes related to neuroinflammation-related neurodegeneration.

Theta oscillations in anterior cingulate cortex and orbitofrontal cortex differentially modulate accuracy and speed in flexible reward learning.

Flexible reward learning relies on frontal cortex, with substantial evidence indicating that anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) subregions play important roles. Recent studies in both rat and macaque suggest theta oscillations (5-10 Hz) may be a spectral signature that coordinates this learning. However, network-level interactions between ACC and OFC in flexible learning remain unclear. We investigated the learning of stimulus-reward associations using a combination of simultaneous in vivo electrophysiology in dorsal ACC and ventral OFC, partnered with bilateral inhibitory DREADDs in ACC. In freely behaving male and female rats and using a within-subject design, we examined accuracy and speed of response across distinct and precisely defined trial epochs during initial visual discrimination learning and subsequent reversal of stimulus-reward contingencies. Following ACC inhibition, there was a propensity for random responding in early reversal learning, with correct vs. incorrect trials distinguished only from OFC, not ACC, theta power differences in the reversal phase. ACC inhibition also hastened incorrect choices during reversal. This same pattern of change in accuracy and speed was not observed in viral control animals. Thus, characteristics of impaired reversal learning following ACC inhibition are poor deliberation and weak theta signaling of accuracy in this region. The present results also point to OFC theta oscillations as a prominent feature of reversal learning, unperturbed by ACC inhibition.

Characterization of striatal dopamine projections across striatal subregions in behavioral flexibility.

Behavioural flexibility is key to survival in a dynamic environmentWhile flexible, goal-directed behaviours are initially dependent on dorsomedial striatum, they become dependent on lateral striatum as behaviours become inflexible. Similarly, lesions of dopamine terminals in lateral striatum disrupt the development of inflexible habits. This work suggests that dopamine release in lateral striatum may drive inflexible behaviours, though few studies have investigated a causative role of subpopulations of striatal dopamine terminals in reversal learning, a measure of flexibility. Here, we performed two optogenetic experiments to activate dopamine terminals in dorsomedial (DMS), dorsolateral (DLS) or ventral (nucleus accumbens [NAc]) striatum in DAT-Cre mice that expressed channelrhodopsin-2 via viral injection (Experiment I) or through transgenic breeding with an Ai32 reporter line (Experiment II) to determine how specific dopamine subpopulations impact reversal learning. Mice performed a reversal task in which they self-stimulated DMS, DLS, or NAc dopamine terminals by pressing one of two levers before action-outcome lever contingencies were reversed. Largely consistent with presumed ventromedial/lateral striatal function, we found that mice self-stimulating medial dopamine terminals reversed lever preference following contingency reversal, while mice self-stimulating NAc showed parial flexibility, and DLS self-stimulation resulted in impaired reversal. Impairments in DLS mice were characterized by more regressive errors and reliance on lose-stay strategies following reversal, as well as reduced within-session learning, suggesting reward insensitivity and overreliance on previously learned actions. This study supports a model of striatal function in which DMS and ventral dopamine facilitate goal-directed responding, and DLS dopamine supports more inflexible responding.

Scopolamine causes delirium-like brain network dysfunction and reversible cognitive impairment without neuronal loss.

Delirium is a severe acute neuropsychiatric syndrome that commonly occurs in the elderly and is considered an independent risk factor for later dementia. However, given its inherent complexity, few animal models of delirium have been established and the mechanism underlying the onset of delirium remains elusive. Here, we conducted a comparison of three mouse models of delirium induced by clinically relevant risk factors, including anesthesia with surgery (AS), systemic inflammation, and neurotransmission modulation. We found that both bacterial lipopolysaccharide (LPS) and cholinergic receptor antagonist scopolamine (Scop) induction reduced neuronal activities in the delirium-related brain network, with the latter presenting a similar pattern of reduction as found in delirium patients. Consistently, Scop injection resulted in reversible cognitive impairment with hyperactive behavior. No loss of cholinergic neurons was found with treatment, but hippocampal synaptic functions were affected. These findings provide further clues regarding the mechanism underlying delirium onset and demonstrate the successful application of the Scop injection model in mimicking delirium-like phenotypes in mice.

The reversible effects of free fatty acids on sulfonylureas-stimulated insulin secretion are related to the expression and dynamin mediated endocytosis of KATP channels in pancreatic β cells.

Lipotoxicity-induced pancreatic β cells-dysfunction results in decreased insulin secretion in response to multiple stimulus. In this study, we investigated the reversible effects of palmitate (PA) or oleate (OA) on insulin secretion and the relationship with pancreatic β cell ATP-sensitive potassium (KATP) channels. MIN6 cells were treated with PA and OA for 48 hr and then washed out for 24 hr to determine the changes in expression and endocytosis of the KATP channels and insulin secretion under glucose- (GSIS) and sulfonylureas-stimulated (SUs-SIS). MIN6 cells exposed to PA or OA showed both impaired GSIS and SUs-SIS, the former was not restorable, while the latter was reversible with wash out of PA or OA. Decreased expressions of both total and surface Kir6.2 and SUR1 and endocytosis of KATP channels were observed which were also recoverable after washed out. When MIN6 cells exposed to FFAs were cotreated with AICAR or dynasore, we found that endocytosis of KATP channels did not change significantly by AICAR, but was almost completely blocked by dynasore. Meanwhile, the inhibition of endocytosis of KATP channels after washed out could be activated by PIP2. The recovery of SUs-SIS after washed out was significantly weakened by PIP2, but the decrease of SUs-SIS induced by FFAs was not alleviated by dynasore. FFAs can cause reversible impairment of SUs-SIS on pancreatic β cells. The reversibility of the effects is partial because of the changes of expression and endocytosis of Kir6.2 and SUR1 which was mediated by dynamin.

Reversal of spatial memory impairment by phosphodiesterase 3 inhibitor cilostazol is associated with reduced neuroinflammation and increased cerebral glucose uptake in aged male mice.

The nucleotide second messenger 3', 5'-cyclic adenosine monophosphate (cAMP) and 3', 5'-cyclic guanosine monophosphate (cGMP) mediate fundamental functions of the brain, including learning and memory. Phosphodiesterase 3 (PDE3) can hydrolyze both cAMP and cGMP and appears to be involved in the regulation of their contents in cells. We previously demonstrated that long-term administration of cilostazol, a PDE3 inhibitor, maintained good memory performance in aging mice. Here, we report on studies aimed at determining whether cilostazol also reverses already-impaired memory in aged male mice. One month of oral 1.5% cilostazol administration in 22-month-old mice reversed age-related declines in hippocampus-dependent memory tasks, including the object recognition and the Morris water maze. Furthermore, cilostazol reduced neuroinflammation, as evidenced by immunohistochemical staining, and increased glucose uptake in the brain, as evidence by positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG). These results suggest that already-expressed memory impairment in aged male mice that depend on cyclic nucleotide signaling can be reversed by inhibition of PDE3. The reversal of age-related memory impairments may occur in the central nervous system, either through cilostazol-enhanced recall or strengthening of weak memories that otherwise may be resistant to recall.

Trans-cinnamaldehyde mitigates rotenone-induced neurotoxicity via inhibiting oxidative stress in rats

BackgroundThe second most prevalent age-related brain condition, Parkinson's disease (PD) is characterised by the loss of neurons in the substantia nigra pars compacta (SNpc). It is associated with symptoms like bradykinesia, stiffness, tremor, and impaired postural responses. Motor dysfunction, and neurochemical imbalance, are involved in the pathophysiology of PD. It has been hypothesised that trans cinnamaldehyde (TCA) a component of Traditional Chinese Medicine (TCM) can ameliorate Parkinson-like symptoms by altering the levels of different biochemical markers and reverse motor impairments. This research sought to determine the neuroprotective effect of TCA against the neurotoxicity caused by rotenone. Basic ProcedureRotenone (1.5 mg/kg/day; s.c. for 35 days) was given to rats to induce Parkinson-like symptoms. TCA (5, 10, and 20 mg/kg) and concomitant treatment of TCA (5 mg/kg) with L-NAME (10 mg/kg) were given one hour prior to rotenone administration. Every week until the 35th day, behavioral parameters (muscle coordination, spontaneous motor movement and gait abnormalities) were assessed using rotarod, actophotometer, and narrow beam apparatus respectfully. Rats were decapitated on the 35th day, the striatum and cortex were isolated for biochemical tests. Main findingsRotenone treatment reduced body weight, altered motor coordination and reduced the oxidative defense system. Treatment with TCA significantly improved the alterations in antioxidant levels as well as behavioral parameters. Furthermore, L-NAME (nitric oxide synthase inhibitor) in combination with TCA had a more significant effect as compared to TCA alone, signifying a possible drug interaction. Principal conclusionTCA could be employed as an adjuvant in PD management.

Superiority of ceftazidime off-label high-dose regimen in PK/PD target attainment during treatment of extensively drug-resistant Pseudomonas aeruginosa infections in cancer patients.

The objective of this study was to evaluate off-label high-dose ceftazidime population pharmacokinetics in cancer patients with suspected or proven extensively drug-resistant (XDR) Pseudomonas aeruginosa infections and then to compare the achievement of the pharmacokinetic/pharmacodynamic (PK/PD) target after standard and off-label high-dose regimens using population model-based simulations. A further aim was to clinically observe the occurrence of adverse effects during the off-label high-dose ceftazidime treatment. In patients treated with off-label high-dose ceftazidime (3 g every 6h), blood samples were collected and ceftazidime serum levels measured using LC-MS/MS. A pharmacokinetic population model was developed using a nonlinear mixed-effects modelling approach and Monte Carlo simulations were then used to compare standard and high-dose regimens for PK/PD target attainment. A total of 14 cancer patients with serious infection suspected of XDR P. aeruginosa aetiology were eligible for PK analysis. XDR P. aeruginosa was confirmed in 10 patients as the causative pathogen. Population ceftazidime volume of distribution was 13.23 L, while clearance started at the baseline of 1.48 L/h and increased by 0.0076 L/h with each 1mL/min/1.73 m2 of eGFR. High-dose regimen showed significantly higher probability of target attainment (i.e., 86% vs. 56% at MIC of 32 mg/L). This was translated into a very low mortality rate of 20%. Only one case of reversible neurological impairment was observed. We proved the superiority of the ceftazidime off-label high-dose regimen in PK/PD target attainment with very low occurrence of adverse effects. The off-label high-dose regimen should be used to optimize treatment of XDR P. aeruginosa infections.

Aniba canelilla (Kunth) Mez essential oil and its primary constituent, 1-nitro-2-phenylethane, inhibits acetylcholinesterase and reverse memory impairment in rodents

Ethnopharmacological relevanceAniba canelilla, distributed in the Amazon region, stands out for its diverse economic and medicinal applications. Studies of the A. canelilla essential oil and its primary constituent, 1-nitro-2-phenylethane, have confirmed its anti-inflammatory, antinociceptive, anti-hypertensive potential, and anticholinesterase, among other therapeutic activities.Aim of the study: In addition, the present work aims to evaluate the potential of oil and NPE in the learning and memory of rodents. Material and methodsThe oil was hydrodistilled and analyzed by GC and GC-MS. The learning and memory action in mice was evaluated through the scopolamine-induced cognitive deficit model, followed by behavioral analysis using Morris's water maze paradigm. ResultsOil provided a yield of 0.5%, and in its chemical composition, 1-nitro-2-phenylethane (NPE) (76.2%) and methyleugenol (19.6%) were identified as primary constituents. Oil fractionation furnished NPE with 99.4%, which was used to evaluate its effects in animal models. Wistar rats were submitted to the mnemonic impairment-scopolamine-induced protocol for 7 days. The oil, NPE, and the positive control donepezil were administered from the 8th to 12th days. Morris water maze results demonstrated that oil and NPE reversed spatial learning and long-term memory similarly induced by muscarinic antagonist scopolamine to donepezil, the positive control. ConclusionThese beneficial effects have led the work to further investigations of the oil and NPE to elucidate their pharmacological mechanism, focusing on the cholinergic pathway of the central nervous system and opening up to the knowledge of other adjacent mechanisms, whose results are still under analysis.

Angiotensin‐(1‐7)/Mas receptor agonist: a disease modifying therapeutic for VCID protects cognitive function and inhibits serum neurofilament light protein

AbstractBackgroundVascular contributions to cognitive impairment and dementia (VCID) and Alzheimer’s disease related dementias (ADRD) are associated with increases in systemic and brain inflammatory cytokines, increased reactive oxygen species (ROS) and decreased brain blood flow. We have completed preclinical development of novel synthetic glycopeptide derivatives of Angiotensin‐(1‐7) (Ang‐1‐7) MasR agonists that have outstanding brain penetration, improved half‐life, reverse cognitive impairment and decreases plasma neurofilament light protein (NfL) in our preclinical model of VCID. Ang‐(1‐7)/MasR mechanisms of action include inhibition of 1) microglia activation, 2) brain cytokines activation and, 3) vascular endothelial ROS production. The purpose of this pilot study was to 1) determine if plasma NfL is increased in coronary artery bypass graft (CABG) surgery patients at‐risk for VCID and 2) determine if treatment with an Ang‐(1‐7)/MasR agonist protects cognitive function post‐surgy and modifies NfL.MethodSubjects were randomly assigned to receive either 200 micrograms/kg/day s.c. (n = 3) or saline‐placebo (n = 2). Injections were begun 2 hours prior to surgery and then daily for 21 days. Cognitive function was measured prior to surgery and at 21‐ and 90‐days post‐surgery. Serum NfL was measured via Quanterix Simoa assay. Statistical analysis was performed using GraphPad and significance tested using Welch’s ANOVA, Dunnett’s post. Memory function was measured using a composite score comprised of memory, executive functioning, language, and processing speed.ResultPlasma levels of NfL prior to surgery were significantly increased by 176% in CABG patients (n = 5) as compared to age‐matched healthy controls (n = 8, p = .003). Treatment with Ang‐(1‐7) for 21‐days via subcutaneous injections protected memory function as measured by both the Face‐Name and Cured Name Retrieval associative memory tests at both 21‐ and 90‐days post ‐surgery and significantly attenuated CABG induced increases in NfL as compared to placebo‐saline treatment (p = .004).ConclusionThese preliminary data suggest that NfL may serve as a biomarker of VCID in CABG surgery patients and for MasR target engagement for VCID‐modifying treatments with Ang‐(1‐7) analogs. We have begun studies to develop NfL as a biomarker for Ang‐(1‐7)/MasR target activation and for patient stratification for treatment of VCID (Supported by NIH U01HL131014, U01AG066623).

Frailty in Patients Undergoing Chimeric Antigen Receptor T-Cell (CAR T) Therapy at Princess Margaret Cancer Centre: A Prospective Pilot Study

Introduction Princess Margaret Cancer Centre is 1 of 3 adult centres in Ontario, Canada providing Chimeric Antigen Receptor T-Cell (CAR T) therapy as a standard of care treatment for patients with relapsed and refractory B-cell lymphoma, with the first patient treated in June 2020. There is no upper age limit for treatment referral, and frailty is an important consideration in assessing fitness for treatment. However, there is limited published research in this area. One study found that fit patients had improved response rates, progression-free survival (PFS), and overall survival (OS), than patients who were unfit/frail (Zhang. Leuk Lymph. 2022). This data supports the need for further characterization of frailty in patients undergoing CAR-T. This study aims to determine if frailty assessments pre-CAR T can predict those at higher risk for acute toxicities, PFS, and OS. Additionally, changes in frailty in the 12 months following treatment compared to baseline will be described. Understanding how CAR T therapy affects a patient's frailty over time will facilitate planning appropriate interventions. Methods We performed a cohort study of consecutive patients with lymphoma undergoing CAR T-cell therapy at our institution, from April 2021 to present. Information regarding clinical presentation, histological subtype, prognostic factors, bridging treatment, and acute toxicity, such immune effector cell-associated neurotoxicity syndrome (ICANS) and CRS, were collected. Frailty was evaluated using the Clinical Frailty Scale (CFS), Grip Strength, Gait Speed, Mini-Cog, Edmonton Symptom Assessment System (ESAS) and Patient Health Questionnaire (PHQ-2 and PHQ-9) at 5 time points: baseline (clearance visit), and 1, 3, 6 and 12 months post-CAR T. We discontinued assessments upon progression. At baseline, additional assessments were completed to further characterize frailty including the Vulnerable Elders Survey (VES-13), Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) and Cumulative Illness Rating Scale (CIRS). Results Thirty patients have been enrolled to date. Mean age was 59 ± 13.5 years and patients were primarily male (58.6%). All 30 patients were diagnosed with non-Hodgkin lymphoma; 46.4% had de novo diffuse large B-cell lymphoma, and 21% had transformation from follicular lymphoma. Median follow-up is 2.9 months (Q1 1.2, Q3 9.4). All 30 patients completed assessments at baseline, 21 completed 1 month, 11 completed 3 month, 5 completed 6 month, and 4 completed 12 month assessments. Median scores on the HCT-CI, CIRS and VES-13 at baseline were 1.0 (Q1 0.0, Q3 3.0), 2.0 (Q1 1.0, Q3 6.0) and 1.0 (Q1 0.0, Q3 5.0), respectively. There were clinically significant changes observed in CFS over time (p=0.043), with mean scores of 3.60 (0.25) at baseline and 2.00 (0.67) at 12 months (Table 1). There were no significant changes (p=0.969; p=0.582) between timepoints for either of the physical assessments of grip strength or gait speed. Compared to other assessments, PHQ total score had a larger difference between timepoints with mean scores of 2.33 (0.93) at baseline and 0.00 (0.00) at 12 months, however, this was not significant (p=0.052), likely related to limited sample size (N=4). When analyzing specific acute toxicities, 7 patients experienced ICANS (Grade 3 7.1%, Grade 2 3.6%, Grade 1 (14.3%)). Twenty-five patients (89.3%) experienced CRS (Grade 2 50.0%, Grade 1 39.3%) during the 30 days following cell re-infusion. There have been 8 progression events (2 patients with progression remain alive), and 7 deaths with 1 occurring without disease progression. There was a 76.9% probability of PFS at 3 months and 64.5% at 6 months, with 3 month and 6 month OS 80.2% and 74.5%. Conclusions The only repeated measurement of frailty that found to have clinically significant changes between timepoints was the CFS, suggesting an element of reversible functional impairment related to patients’ lymphoma. Overall patients appear to be impaired at baseline, worsen through the first 1-3 months, and improve by 12 month if in remission. However, the number of patients who completed the 12 month visit to date is small and more data is needed from ongoing follow-up and accrual. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Time to Event Surrogate Endpoints in Multiple Myeloma Randomized Trials from 2005-2019: A Surrogacy Analysis

INTRODUCTIONThe use of surrogate endpoints such as progression-free survival (PFS) and other time-to-event (TTE) endpoints is common in multiple myeloma (MM) clinical trials. However, the validity of these alternative endpoints as surrogates for overall survival is not consistently proven in most malignancies, including MM, and requires further investigation. Furthermore, relapses in MM may occur clinically (with the appearance of new lytic lesions or extramedullary disease) or biochemically, with a rise of a monoclonal protein. As clinical progression may be more prognostically relevant than asymptomatic biochemical progression, it is important for clinical trials to include the nature of progression as part of their results. For all randomized trials that used a primary or co-primary time-to-event endpoint such as PFS, event-free survival (EFS) and time-to-progression (TTP), we assessed whether progression was reported as a biochemical progression or a clinical progression and whether a benefit in PFS translated to an OS benefit upon extended follow-up. We also performed a surrogacy analysis of PFS for OS in these trials to evaluate the strength of surrogacy. METHODS Three databases were searched (MEDLINE/PubMed, Embase, and Cochrane Registry of Controlled Trials) for all RCTs in MM from 2005 to 2019. The primary objectives of this study were twofold, to evaluate the proportion of RCTs using time-to-event endpoints that reported whether progression was biochemical and/or clinical, and to evaluate the strength of surrogacy of PFS to OS for all RCT's that used PFS as a primary or co-primary endpoint. We used an unadjusted linear regression to evaluate the association between OS HR and PFS HR for studies reporting time-concurrent numbers, or for studies reporting OS at a later follow up, and to calculate the coefficient of determination (R2). We also calculated Pearson's correlation coefficients and 95% confidence intervals for the correlation coefficients. We classified the strength of association as weak (r ≤ 0.7), medium (r > 0.7 to r < 0.85), and strong (r ≥ 0.85). RESULTS The initial search strategy yielded 1171 results. After searching conference proceedings and excluding duplicates or studies not meeting inclusion criteria, 151 discrete RCTs were included. When substratified for only those trials that were primarily evaluating time-to-event endpoints, a total of 88 studies were identified, of which 67 had PFS as either a primary or co-primary endpoint. A total of 45 studies included HR for both PFS and OS, allowing for regression analysis. Table 1 lists characteristics of included studies. We found only one study that described whether progression events were biochemical or clinical. Two additional studies reported time to first skeletal event and renal impairment reversal respectively but did not clearly differentiate between biochemical and clinical progression. Amongst the 45 studies where correlation could be assessed, the R2 from the regression model suggested that among the variance in OS, 45% was explained by PFS (Figure 1). The correlation between PFS and OS was 0.67 (95% CI 0.47-0.81), indicating a weak association of PFS with OS. For newly diagnosed (n=21) studies, 39% of the variance in OS was due to changes in PFS. The correlation between PFS and OS was 0.63 (95% CI 0.27-0.83) indicating a weak association of PFS with OS. For studies of relapsed/refractory MM (n=20), 60% of the variance in OS was due to changes in PFS. The correlation between PFS and OS was 0.77 (95% CI 0.49-0.91), indicating a medium association of PFS with OS. CONCLUSION We demonstrate that PFS is characterized poorly in MM trials, with almost no trials identifying whether progression events are biochemical or clinical. Our results show that PFS is a poor surrogate for OS in MM, especially for newly diagnosed disease. This review highlights the need for more comprehensive reporting of progression characteristics in order to establish the magnitude of clinical benefit to our patients. While acknowledging the tremendous improvements in outcomes in patients with MM with the current framework of trials, we highlight that differences in PFS do not reliably predict differences in OS, and we urge caution in attempts to establish surrogacy of other outcomes such as measurable residual disease with PFS. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Donepezil prevents olfactory dysfunction and α-synuclein aggregation in the olfactory bulb by enhancing autophagy in zinc sulfate-treated mice

Alzheimer’s disease is associated with marked olfactory dysfunction observed in the early stages. Clinical studies reported that acetylcholinesterase inhibitor donepezil (DNP) attenuated this deficit; however, the underlying mechanism remains unclear. Herein, we aimed to examine the effects and underlying mechanisms of DNP on olfactory deficits in zinc sulfate (ZnSO4) nasal-treated mice, which were used as a model of reversible olfactory impairment. We evaluated olfactory function using the buried food finding test and neurogenesis in the subventricular zone (SVZ) using immunohistochemistry. Finally, we measured the expression of doublecortin (DCX), neuronal nuclear antigen (NeuN), olfactory marker protein, tyrosine hydroxylase (TH), tryptophan hydroxylase 2, glutamic acid decarboxylase 67, p-α-synuclein (Ser129), α-synuclein, p-AMPK, p-p70S6 kinase (p70S6K) (Thr389), LC3 Ⅱ/Ⅰ, and p-p62 in the olfactory bulb (OB) by western blotting. On day 7 after treatment, ZnSO4-treated mice exhibited prolonged time to find the buried food, cell proliferation enhancement in the SVZ, increased NeuN, p-α-synuclein (Ser129), and α-synuclein levels, and decreased DCX and TH levels in the OB; except for TH, these changes normalized on day 14 after treatment. Repeated administration of DNP prevented the ZnSO4-induced changes on day 7 after treatment. Moreover, DNP increased p-AMPK and LC3 Ⅱ/Ⅰ, and decreased p-p70S6K and p-p62 (Ser351) levels in the OB, suggesting that DNP enhances autophagy in the OB. These findings indicate that DNP may help prevent olfactory dysfunction by autophagy that reduces α-synuclein aggregation via the AMPK/mTOC1 pathway.

Reversal of neurovascular decoupling and cognitive impairment in patients with end-stage renal disease during a hemodialysis session: Evidence from a comprehensive fMRI analysis.

Neurovascular (NV) decoupling is a potential neuropathologic mechanism of cognitive impairment in patients with end-stage renal disease (ESRD). Hemodialysis improves cognitive impairment at 24 h post-dialysis, which suggests a potential neuroprotective effect of hemodialysis treatment on the brain. We investigated the effects of hemodialysis treatment on the reversal of NV decoupling associated with cognitive improvement. A total of 39 patients with ESRD and 39 healthy controls were enrolled. All patients were imaged twice during a dialysis session: before hemodialysis (T1pre-dialysis ) and at 24 h after dialysis (T2post-dialysis ). The healthy controls were imaged once. NV coupling was characterized based on correlation coefficients between four types of blood oxygen level-dependent signals and cerebral blood flow (CBF). A battery of neuropsychological and blood tests was performed before the imaging. Patients with ESRD showed improvements in memory and executive function at T2post-dialysis compared with that at T1pre-dialysis . At both T1pre-dialysis and T2post-dialysis , patients with ESRD had lower amplitude of low-frequency fluctuation (ALFF)-CBF coupling than healthy controls. Additionally, patients with ESRD had higher ALFF-CBF coupling at T2post-dialysis than at T1pre-dialysis . Higher memory scores, higher hemoglobin level, lower total plasma homocysteine level, lower systolic blood pressure variance, and lower ultrafiltration volume were associated with higher ALFF-CBF coupling in patients with ESRD after a hemodialysis session. These findings indicate that partial correction of anemia and hyperhomocysteinemia, stable systolic blood pressure, and fluid restriction may be closely linked to the reversal of NV decoupling and improvement in cognition in patients with ESRD.

Assessing the Reversibility of Renal Impairment in Patients Awaiting Heart Transplantation.

Assessing the Reversibility of Renal Impairment in Patients Awaiting Heart Transplantation.

Orbitofrontal cortex populations are differentially recruited to support actions

The ability to use information from one's prior actions is necessary for decision-making. While orbitofrontal cortex (OFC) has been hypothesized as key for inferences made using cue and value-related information, whether OFC populations contribute to the use of information from volitional actions to guide behavior is not clear. Here, we used a self-paced lever-press hold-down task in which mice infer prior lever-press durations to guide subsequent action performance. We show that the activity of genetically identified lateral OFC (lOFC) subpopulations differentially instantiate current and prior action information during ongoing action execution. Transient state-dependent lOFC circuit disruptions of specified subpopulations reduced the encoding of ongoing press durations but did not disrupt the use of prior action information to guide future action performance. In contrast, a chronic functional loss of lOFC circuit activity resulted in increased reliance on recently executed lever-press durations and impaired contingency reversal, suggesting the recruitment of compensatory mechanisms that resulted in repetitive action control. Our results identify a novel role for lOFC in the integration of action information to guide adaptive behavior.

Enhanced fear limits behavioral flexibility in Shank2-deficient mice

BackgroundA core symptom of autism spectrum disorder (ASD) is repetitive and restrictive patterns of behavior. Cognitive inflexibility has been proposed as a potential basis for these symptoms of ASD. More generally, behavioral inflexibility has been proposed to underlie repetitive and restrictive behavior in ASD. Here, we investigated whether and how behavioral flexibility is compromised in a widely used animal model of ASD.MethodsWe compared the behavioral performance of Shank2-knockout mice and wild-type littermates in reversal learning employing a probabilistic classical trace conditioning paradigm. A conditioned stimulus (odor) was paired with an unconditioned appetitive (water, 6 µl) or aversive (air puff) stimulus in a probabilistic manner. We also compared air puff-induced eye closure responses of Shank2-knockout and wild-type mice.ResultsMale, but not female, Shank2-knockout mice showed impaired reversal learning when the expected outcomes consisted of a water reward and a strong air puff. Moreover, male, but not female, Shank2-knockout mice showed stronger anticipatory eye closure responses to the air puff compared to wild-type littermates, raising the possibility that the impairment might reflect enhanced fear. In support of this contention, male Shank2-knockout mice showed intact reversal learning when the strong air puff was replaced with a mild air puff and when the expected outcomes consisted of only rewards.LimitationsWe examined behavioral flexibility in one behavioral task (reversal learning in a probabilistic classical trace conditioning paradigm) using one ASD mouse model (Shank2-knockout mice). Thus, future work is needed to clarify the extent to which our findings (that enhanced fear limits behavioral flexibility in ASD) can explain the behavioral inflexibility associated with ASD. Also, we examined only the relationship between fear and behavioral flexibility, leaving open the question of whether abnormalities in processes other than fear contribute to behavioral inflexibility in ASD. Finally, the neurobiological mechanisms linking Shank2-knockout and enhanced fear remain to be elucidated.ConclusionsOur results indicate that enhanced fear suppresses reversal learning in the presence of an intact capability to learn cue-outcome contingency changes in Shank2-knockout mice. Our findings suggest that behavioral flexibility might be seriously limited by abnormal emotional responses in ASD.

Prenatal cyanuric acid exposure disrupts cognitive flexibility and mGluR1-mediated hippocampal long-term depression in male rats

Cyanuric acid is one of the most widely used classes of industrial chemicals and is now well known as food adulterant and contaminant in pet food and infant formula. Previously, it was reported that animals prenatally exposed to cyanuric acid showed neurotoxic effects that impaired memory consolidating and suppressed long-term potentiation (LTP) in the hippocampus. However, it is not clear if prenatal exposure to cyanuric acid induces deficits in reversal learning and long-term depression (LTD), which is required for the developmental reorganization of synaptic circuits and updating learned behaviors. Here, pregnant rats were i.p. injected with cyanuric acid (20 mg/kg) during the whole of gestation, and male offspring were selected to examine the levels of hippocampal mGluR1 and mGluR2/3 in young adulthood. The LTD at the Schaffer collateral-CA1 pathway was induced by low-frequency stimulation (LFS) and recorded. Reversal learning and hippocampus-dependent learning strategy were tested in Morris-water maze (MWM) and T-maze tasks, respectively. To further confirm the potential mechanism, selective agonists of mGluR1 and mGluR2/3 and antagonists of mGluR were intra-hippocampal infused before behavioral and neuronal recording. We found the levels of alkaline phosphatase were markedly increased in the maternal placenta and fetal brain following prenatal exposure. The expression of mGluR1 but not mGluR2/3 was significantly decreased and mGluR1-mediated LTD was selectively weakened. Prenatal cyanuric acid impaired reversal learning ability, without changing place learning strategy. The mGluR1 agonist could effectively enhance LFS-induced LTD and mitigate reversal learning deficits. Meanwhile, the reductions in the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPAR)-mediated spontaneous excitatory postsynaptic currents (sEPSCs) amplitude and frequency of cyanuric acid offspring were simultaneously alleviated by mGluR1 agonist infusions. Therefore, the results indicate the cognitive and synaptic impairments induced by prenatal cyanuric acid exposure are attributed to the disruption of the hippocampal mGluR1 signaling. Our findings provided the first evidence for the deteriorated effects of cyanuric acid on synaptic depression and advanced cognitive performance.