Sex, hormones and cerebrovascular function: from development to disorder

Proper cerebrovascular development and neurogliovascular unit assembly are essential for brain growth and function throughout life, ensuring the continuous supply of nutrients and oxygen. This involves crucial events during pre- and postnatal stages through key pathways, including vascular endothelial growth factor (VEGF) and Wnt signaling. These pathways are pivotal for brain vascular growth, expansion, and blood-brain barrier (BBB) maturation. Interestingly, during fetal and neonatal life, cerebrovascular formation coincides with the early peak activity of the hypothalamic-pituitary-gonadal axis, supporting the idea of sex hormonal influence on cerebrovascular development and barriergenesis.Sex hormonal dysregulation in early development has been implicated in neurodevelopmental disorders with highly sexually dimorphic features, such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). Both disorders show higher prevalence in men, with varying symptoms between sexes, with boys exhibiting more externalizing behaviors, such as aggressivity or hyperactivity, and girls displaying higher internalizing behaviors, including anxiety, depression, or attention disorders. Indeed, ASD and ADHD are linked to high prenatal testosterone exposure and reduced aromatase expression, potentially explaining sex differences in prevalence and symptomatology. In line with this, high estrogen levels seem to attenuate ADHD symptoms. At the cerebrovascular level, sex- and region-specific variations of cerebral blood flow perfusion have been reported in both conditions, indicating an impact of gonadal hormones on the brain vascular system, disrupting its ability to respond to neuronal demands.This review aims to provide an overview of the existing knowledge concerning the impact of sex hormones on cerebrovascular formation and maturation, as well as the onset of neurodevelopmental disorders. Here, we explore the concept of gonadal hormone interactions with brain vascular and BBB development to function, with a particular focus on the modulation of VEGF and Wnt signaling. We outline how these pathways may be involved in the underpinnings of ASD and ADHD. Outstanding questions and potential avenues for future research are highlighted, as uncovering sex-specific physiological and pathological aspects of brain vascular development might lead to innovative therapeutic approaches in the context of ASD, ADHD and beyond.

Focal HDR brachytherapy boost to stereotactic radiotherapy (fBTsRT) for prostate cancer: a phase II randomized controlled trial

BACKGROUND

For patients with a higher burden of localized prostate cancer, radiation dose escalation with brachytherapy boosts have improved cancer control outcomes at the cost of urinary toxicity. We hypothesize that a focal approach to brachytherapy boosts targeting only grossly visualized tumor volumes (GTV) combined with stereotactic radiotherapy will improve quality of life (QoL) outcomes without compromising cancer control.

METHODS

150 patients with intermediate or high-risk prostate cancer will be enrolled and randomized 1:1 in a cohort multiple randomized clinical trial phase 2 design. Patients are eligible if planned for standard-of-care (SOC) high dose rate (HDR) brachytherapy boost to radiotherapy (RT) with GTVs encompassing < 50% of the prostate gland. Those randomly selected will be offered the experimental treatment, consisting of focal HDR brachytherapy boost (fBT) of 13-15 Gy in 1 fraction followed by stereotactic radiotherapy (sRT) 36.25-40 Gy in 5 fractions to the prostate (+/- 25 Gy to the elective pelvis) delivered every other day. The primary endpoint is to determine if fBTsRT is superior to SOC by having fewer patients experience a minimally important decline (MID) in urinary function as measured by EPIC-26 at 1 and 2 years. Secondary endpoints include rates of toxicity measured by Common Terminology Criteria for Adverse Events (CTCAE), and failure-free survival outcomes.

DISCUSSION

This study will determine whether a novel approach for the treatment of localized prostate cancer, fBTsRT, improves QoL and merits further evaluation. Trial registration This trial was prospectively registered in ClinicalTrials.gov as NCT04100174 as a companion to registry NCT03378856 on September 24, 2019.

Predict, prevent and manage moral injuries in Canadian frontline healthcare workers and leaders facing the COVID-19 pandemic: Protocol of a mixed methods study

Moral injuries can occur when perpetrating, failing to prevent, or bearing witness to acts that transgress deeply held moral beliefs and expectations. The COVID-19 crisis highlighted the fact that psychosocial stressors at work, such as high emotional demands, are placing Canadian healthcare workers at risk of moral injuries. Evidence linking psychosocial stressors at work to moral injuries are needed to better predict, prevent and manage moral injuries, as these stressors are frequent and modifiable occupational risk factors. This protocol presents a study aiming to: 1) understand workplace events having the potential to either cause or reduce moral injuries, 2) predict the risk and severity of moral injuries using a disease prevention model, 3) identify biological signatures (biomarkers) associated with psychosocial stressors at work and moral injuries and 4) elaborate preliminary guidelines of organizational practices for frontline healthcare workers to reduce and manage moral injuries. This study is a mixed methods research with three components: qualitative, quantitative and biological. The data collection has been completed and because of the COVID-19 pandemic, it was adjusted to allow for gathering qualitative and quantitative data remotely. Frontline healthcare workers and leaders were included. Through focus groups and individual interviews, and an online questionnaire, events and psychosocial working conditions that may increase the risk of moral injuries will be documented. In addition, blood samples which were collected from a sub-sample of volunteer participants will measure an innovative set of biomarkers associated with vulnerability to stress and mental health. Data analyses are ongoing. We anticipate to identify workplace events that may trigger moral injuries. We expect that potential predictors of moral injury risk occurrence and severity will be identified from psychosocial stressors at work that can be improved by implementing organizational practices. We also expect to observe a different mental health state and biological inflammation signature across workers exposed compared to workers not exposed to psychosocial stressors at work. Based on these future findings, we intend to develop preliminary recommendations of organizational practices for managers. This research will contribute to expand our knowledge of the events in the workplace likely to generate or lessen the impact moral injuries, to build a model for predicting the risk of moral injuries at work, all in the specific context of the COVID-19 health crisis among healthcare workers.

A146 EVALUATION OF A COLONOSCOPY REFERRAL FORM IN QUEBEC: WHICH INDICATIONS CARRIES A HIGHER RISK OF ADVANCED NEOPLASIA?

Background

Patients referral for colonoscopy in the province of Quebec are organized through a standardized triage sheet that includes all indications categorized in 5 hierarchal scheduling priorities. In the context of a restricted access to colonoscopy, exacerbated by the COVID-19 pandemic, postponed elective endoscopies lead to potential diagnostic and therapeutic delays in patients with colorectal neoplasia. There is currently an important need to evaluate available tools to improve patients prioritization.

Aims

This study aims to determine CRC and advanced adenomas (AA) rates associated with indications of priority 3 (P3 fig.1). The secondary objective is to regroup and compare indications with higher and lower rate of CRC and AA.

Methods

This retrospective study included all adult patients who underwent a single diagnostic colonoscopy from March 2013 to March 2016 following a single FIT test in a tertiary teaching hospital. A literature review informed the adopted definition of higher-risk of CRC and AA according to P3 colonoscopy indications. These include: Positive FIT test (IN5), hematochezia in ≥ 40 years old patients (IN4), unexplained iron deficiency anemia (IN6) and symptoms suspicious of occult colorectal cancer (IN18). Lower risk P3 indications were defined as: suspicion of IBD (IN3), recent change in bowel habits (IN7), polyp viewed on imaging (IN17), inadequate bowel preparation (IN19), and diverticulitis follow-up (IN20). Higher and lower risk indications findings were analyzed.

Results

In our cohort of 2226 patients, indications for colonoscopy referral according to the standardized form were available for 1806 patients (10 P1, 69 P2, 1056 P3, 56 P4 and 615 P5). In our studied group of P3 indications, the mean age was 62.6±11.3 years, 54.1% were female and 173 (16.4%) patients had a significant finding of CRC or AA (table 1). Patients referred for higher risk indications had a significantly increased rate of CRC and AA (19.3% vs 5.1% p≤ 0.01) compared to patients referred for lower risk indications.

Conclusions

A standardized colonoscopy referral tool may be adapted to improve prioritization of patients at risk of advanced neoplasia. These findings are especially relevant in the context of limited access to colonoscopy like during a pandemic.

Funding Agencies

None

A1 COLONOSCOPY FINDINGS FOLLOWING A FECAL IMMUNOCHEMICAL TEST: A RETROSPECTIVE STUDY ASSESSING THE SCREENING TEST PERFORMANCE

Background

Fecal Immunochemical Testing (FIT) is the preferred test for colorectal cancer screening in the average risk population in Canada.

Aims

This study aims to assess colonoscopy findings in patients who have undergone a FIT within the previous 2 years.

Methods

This retrospective study included all adult patients that have undergone a single diagnostic colonoscopy from March 2013 to March 2016 following a single FIT test at the CIUSSS de l’Estrie, a tertiary hospital. The primary outcome was to evaluate rates of clinically significant lesion when comparing FIT positive (FIT+) to FIT negative (FIT-) colonoscopy, using Quebec’s current threshold of 175 ng/ml of hemoglobin. Secondary outcomes included all other type of lesions, delays between FIT testing and colonoscopy, procedural time, caecal intubation rates and withdrawal time.

Results

Overall, 2230 patients were included, aged 62.0±10.5 years, 55.0% were female and 26.1% had a positive FIT. Patients with a positive FIT had a significantly higher polypectomy rate (62.4% vs 41.3%, p&lt;0.01) and higher number of polyps per patient (2.9±2.5 vs 2.1±1.5, p&lt;0.01). FIT+ had significantly higher rates of adenocarcinoma (3.4% vs 0.7%, p&lt;0.01) with 11 out of 31 patients bearing a negative FIT with the current threshold. No difference was found for sessile serrated polyps (7.8% vs 6.0%, p=0.13). Patients with a FIT+ had significantly higher advanced adenomas (24.0% vs 5.6%, p&lt;0.01), proximal polyps (33.6% vs 22.4%, p&lt;0.01), distal polyps (52.8% vs 28.2%, p&lt;0.01), non-advanced adenomas (38.5% vs 23.9%, p&lt;0.01) and benign polyps (25.1% vs 17.2%, p&lt;0.01). Patients with FIT+ received their colonoscopy 7.5 months earlier than FIT- patients (3.3±2.2 vs 10.8±8.3 months, p&lt;0.01). FIT+ also yielded a significant longer procedural time (28.5±14.1 vs 25.5±12.1, p&lt;0.01) but no difference was noted for caecal intubation rates and withdrawal time (93.3% vs 94.0%, p=0.55 and 14.0±8.4 vs 12.0±7.7, p=0.20 respectively). Results were similar when lowering the threshold to 150, 100, 75 and even 50 ng/ml. 8 patients with an adenocarcinoma had a FIT level lower than 50 ng/ml.

Conclusions

Patients with a colonoscopy and a positive FIT have higher rates of significant findings. Although commonly used for colorectal cancer screening, FIT still failed to detect almost 30% of adenomas and adenocarcinomas found during colonoscopy. It also does not perform very well for serrated polyps. Our data also fails to show an improved yield of the FIT when lowering the its threshold from 175 to 50. There is still a great need for a more sensitive non-invasive colon cancer screening test.

Funding Agencies

None

Quantitative Determination of Paralytic Shellfish Poisoning Toxins in Shellfish Using Prechromatographic Oxidation and Liquid Chromatography with Fluorescence Detection: Collaborative Study

A collaborative study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3; together), gonyautoxins 1 and 4 (GTX1,4; together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2; together), and C-3 and C-4 (C3,4; together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with clams, oysters, and scallops. Twenty-one test samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries. It is recommended that the method be adopted First Action by AOAC INTERNATIONAL.

The Tyrosine Phosphatase STEP Is Involved in Age-Related Memory Decline

Cognitive disabilities that occur with age represent a growing and expensive health problem. Age-associated memory deficits are observed across many species, but the underlying molecular mechanisms remain to be fully identified. Here, we report elevations in the levels and activity of the striatal-enriched phosphatase (STEP) in the hippocampus of aged memory-impaired mice and rats, in aged rhesus monkeys, and in people diagnosed with amnestic mild cognitive impairment (aMCI). The accumulation of STEP with aging is related to dysfunction of the ubiquitin-proteasome system that normally leads to the degradation of STEP. Higher level of active STEP is linked to enhanced dephosphorylation of its substrates GluN2B and ERK1/2, CREB inactivation, and a decrease in total levels of GluN2B and brain-derived neurotrophic factor (BDNF). These molecular events are reversed in aged STEP knockout and heterozygous mice, which perform similarly to young control mice in the Morris water maze (MWM) and Y-maze tasks. In addition, administration of the STEP inhibitor TC-2153 to old rats significantly improved performance in a delayed alternation T-maze memory task. In contrast, viral-mediated STEP overexpression in the hippocampus is sufficient to induce memory impairment in the MWM and Y-maze tests, and these cognitive deficits are reversed by STEP inhibition. In old LOU/C/Jall rats, a model of healthy aging with preserved memory capacities, levels of STEP and GluN2B are stable, and phosphorylation of GluN2B and ERK1/2 is unaltered. Altogether, these data suggest that elevated levels of STEP that appear with advancing age in several species contribute to the cognitive declines associated with aging.

Procarbazine, lomustine and vincristine toxicity in low-grade gliomas

Background

Procarbazine, lomustine, and vincristine (pcv) significantly improve survival outcomes in lgg (low-grade gliomas). Administration of pcv to lgg patients increased tremendously over the past years as it went from 2 patients per year between 2005 and 2012 to 23 patients in 2015 only in our centre. However, serious hematological and non-hematological adverse events may occur. The purpose of this study was to evaluate the toxicity of pcv and its clinical relevance in our practice.

Methods

We retrospectively reviewed the charts of 57 patients with lgg who received pcv at the Centre hospitalier de l'Université de Montréal between 1 January 2005 and 27 July 2016.

Results

Procarbazine, lomustine, and vincristine were associated with severe hematological toxicity as clinically significant grade 3 anemia, neutropenia, and thrombocytopenia occurred in 7%, 10%, and 28% of patients, respectively. Other frequent adverse events such as the increase of liver enzymes, cutaneous rash, neurotoxicity, and vomiting occurred in 65%, 26%, 60%, and 40% of patients, respectively. Patients with prophylactic trimethoprim/sulfamethoxazole had more grade 3 hematological toxicity with pcv, especially anemia (p = 0.040) and thrombocytopenia (p = 0.003) but we found no increase in pcv toxicity in patients on concurrent anticonvulsants. Patients with grade 3 neutropenia had a significantly lower survival (median survival 44.0 months vs. 114.0 months, p = 0.001). Patients who were given pcv at diagnosis had more grade 3 anemia than those who received it at subsequent lines of treatment (p = 0.042).

Conclusion

Procarbazine, lomustine, and vincristine increase survival in lgg but were also associated with major hematologic, hepatic, neurologic, and cutaneous toxicity. Anti-Pneumocystis jiroveci pneumonia (pjp) prophylaxis, but not anticonvulsants, enhances hematologic toxicity.

Inflammatory Mediators in Mood Disorders: Therapeutic Opportunities

Mood disorders such as depression are among the most prevalent psychiatric disorders in the United States, but they are inadequately treated in a substantial proportion of patients. Accordingly, neuropsychiatric research has pivoted from investigation of monoaminergic mechanisms to exploration of novel mediators, including the role of inflammatory processes. Subsets of mood disorder patients exhibit immune-related abnormalities, including elevated levels of proinflammatory cytokines, monocytes, and neutrophils in the peripheral circulation; dysregulation of neuroglia and blood-brain barrier function; and disruption of gut microbiota. The field of psychoneuroimmunology is one of great therapeutic opportunity, yielding experimental therapeutics for mood disorders, such as peripheral cytokine targeting antibodies, microglia and astrocyte targeting therapies, and probiotic treatments for gut dysbiosis, and producing findings that identify therapeutic targets for future development.

The Association between Generalized Anxiety Disorder, Subthreshold Anxiety Symptoms and Fear of Falling among Older Adults: Preliminary Results from a Pilot Study

OBJECTIVE

A relationship between generalized anxiety disorder (GAD) and fear of falling (FOF) has long been proposed but never specifically studied. This study aimed at analyzing the relationship between FOF and GAD or anxiety symptoms, while controlling for major depressive episodes (MDE), depressive symptoms, fall risk, and sociodemographic variables.

METHODS

Twenty-five older adults participated in this pilot study. Assessments included the following: Anxiety Disorder Interview Schedule, Geriatric Anxiety Inventory, Geriatric Depression Scale, Falls-Efficacy Scale-International. A multidisciplinary team evaluated fall risk.

RESULTS

FOF was significantly correlated with GAD, MDE, anxiety and depressive symptoms, and fall risk, but not with sociodemographic variables. Multiple regression analyses indicated that GAD and anxiety symptoms were significantly and independently associated with FOF.

CONCLUSION

Although the results of this pilot study should be replicated with larger samples, they suggest that FOF is associated with GAD and anxiety symptoms even when considering physical factors that increase the risk of falling.

CLINICAL IMPLICATIONS

Treatment of FOF in patients with GAD may present a particular challenge because of the central role of intolerance of uncertainty, which may prevent patients from regaining confidence despite the reduction of fall risk. Clinicians should screen for GAD and anxiety symptoms in patients with FOF to improve detection and treatment.

The utilization of magnetic resonance imaging in the operating room

Online image guidance in the operating room using ultrasound imaging led to the resurgence of prostate brachytherapy in the 1980s. Here we describe the evolution of integrating MRI technology in the brachytherapy suite or operating room. Given the complexity, cost, and inherent safety issues associated with MRI system integration, first steps focused on the computational integration of images rather than systems. This approach has broad appeal given minimal infrastructure costs and efficiencies comparable with standard care workflows. However, many concerns remain regarding accuracy of registration through the course of a brachytherapy procedure. In selected academic institutions, MRI systems have been integrated in or near the brachytherapy suite in varied configurations to improve the precision and quality of treatments. Navigation toolsets specifically adapted to prostate brachytherapy are in development and are reviewed.

Predictors of physicians' satisfaction with their management of uncertainty during a decision-making encounter with a simulated advanced stage cancer patient

OBJECTIVES

To optimize their training, predictors of physicians' satisfaction with their management of uncertainty should be examined. This study investigated these predictors by using a simulated advanced stage cancer patient.

METHODS

Physicians (n=85) rated their satisfaction with their management of uncertainty (Visual Analog Scale-100mm) after a decision-making encounter. Communication predictors were examined with the: Observing Patient Involvement scale (OPTION), Multidimensional analysis of Patient Outcome Predictions (MD.POP) and Communication Content Analysis Software (LaComm). Psychological predictors were assessed with the: Intolerance of Uncertainty Inventory (IUI), Physicians' Reactions to Uncertainty scale (PRU), Decisional Conflict Scale (DCS), and Jefferson Scale of Physician Empathy (JSPE).

RESULTS

Physicians' satisfaction (mean=67mm; standard deviation=17mm) was not predicted by their communication, but by their anxiety due to uncertainty (PRU) (β=-.42; p=<.001) and their perceived empathy (JSPE) (β=.26; p=.009). These variables accounted for 25% of variance in physicians' satisfaction.

CONCLUSIONS

Physicians' satisfaction with their management of uncertainty was not affected by their communication performance, but by their psychological characteristics.

PRACTICE IMPLICATIONS

Training programs should increase physicians' awareness regarding the communication performance required in decision-making encounters under conditions of uncertainty.

Integrating Interleukin-6 into depression diagnosis and treatment

There is growing evidence of a relationship between inflammation and psychiatric illness. In particular, the cytokine Interleukin-6 (IL-6) has been linked to stress-related disorders such as depression and anxiety. Here we discuss evidence from preclinical and clinical studies examining the role of IL-6 in mood disorders. We focus on the functional role of peripheral and central release of IL-6 on the development of stress susceptibility and depression-associated behavior. By examining the contribution of both peripheral and central IL-6 to manifestations of stress-related symptomatology, we hope to broaden the way the field thinks about diagnosing and treating mood disorders.

Pathogenesis of depression: Insights from human and rodent studies

Major depressive disorder (MDD) will affect one out of every five people in their lifetime and is the leading cause of disability worldwide. Nevertheless, mechanisms associated with the pathogenesis of MDD have yet to be completely understood and current treatments remain ineffective in a large subset of patients. In this review, we summarize the most recent discoveries and insights for which parallel findings have been obtained in human depressed subjects and rodent models of mood disorders in order to examine the potential etiology of depression. These mechanisms range from synaptic plasticity mechanisms to epigenetics and the immune system where there is strong evidence to support a functional role in the development of specific depression symptomology. Ultimately we conclude by discussing how novel therapeutic strategies targeting central and peripheral processes might ultimately aid in the development of effective new treatments for MDD and related stress disorders.

Signaling pathways relevant to cognition-enhancing drug targets

Aging is generally associated with a certain cognitive decline. However, individual differences exist. While age-related memory deficits can be observed in humans and rodents in the absence of pathological conditions, some individuals maintain intact cognitive functions up to an advanced age. The mechanisms underlying learning and memory processes involve the recruitment of multiple signaling pathways and gene expression, leading to adaptative neuronal plasticity and long-lasting changes in brain circuitry. This chapter summarizes the current understanding of how these signaling cascades could be modulated by cognition-enhancing agents favoring memory formation and successful aging. It focuses on data obtained in rodents, particularly in the rat as it is the most common animal model studied in this field. First, we will discuss the role of the excitatory neurotransmitter glutamate and its receptors, downstream signaling effectors [e.g., calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase C (PKC), extracellular signal-regulated kinases (ERK), mammalian target of rapamycin (mTOR), cAMP response element-binding protein (CREB)], associated immediate early gene (e.g., Homer 1a, Arc and Zif268), and growth factors [insulin-like growth factors (IGFs) and brain-derived neurotrophic factor (BDNF)] in synaptic plasticity and memory formation. Second, the impact of the cholinergic system and related modulators on memory will be briefly reviewed. Finally, since dynorphin neuropeptides have recently been associated with memory impairments in aging, it is proposed as an attractive target to develop novel cognition-enhancing agents.

Glutamate presynaptic vesicular transporter and postsynaptic receptor levels correlate with spatial memory status in aging rat models

In humans, memory capacities are generally affected with aging, even without any reported neurologic disorders. The mechanisms behind cognitive decline are not well understood. We studied here whether postsynaptic glutamate receptor and presynaptic vesicular glutamate transporters (VGLUTs) levels may change in the course of aging and be related to cognitive abilities using various age-impaired (AI) or age-unimpaired rat strains. Twenty-four-month-old Long-Evans (LE) rats with intact spatial memory maintained postsynaptic ionotropic glutamate receptor levels in the hippocampal-adjacent cortex similar to those of young animals. In contrast, AI rats showed significantly reduced expression of ionotropic glutamate receptor GluR2, NR2A and NR2B subunits. In AI LE rats, VGLUT1 and VGLUT2 levels were increased and negatively correlated with receptor levels as shown by principal component analysis and correlation matrices. We also investigated whether glutamatergic receptors and VGLUT levels were altered in the obesity-resistant LOU/C/Jall (LOU) rat strain which is characterized by intact memory despite aging. No difference was observed between 24-month-old LOU rats and their young counterparts. Taken together, the unaltered spatial memory performance of 24-month-old age-unimpaired LE and LOU rats suggests that intact coordination of the presynaptic and postsynaptic hippocampal-adjacent cortex glutamatergic networks may be important for successful cognitive aging. Accordingly, altered expression of presynaptic and postsynaptic glutamatergic components, such as in AI LE rats, could be considered a marker of age-related cognitive deficits.

Neuroprotective action of resveratrol

Low-to-moderate red wine consumption appeared to reduce age-related neurological disorders including macular degeneration, stroke, and cognitive deficits with or without dementia. Resveratrol has been considered as one of the key ingredients responsible for the preventive action of red wine since the stilbene displays a neuroprotective action in various models of toxicity. Besides its well documented free radical scavenging and anti-inflammatory properties, resveratrol has been shown to increase the clearance of beta-amyloid, a key feature of Alzheimer's disease, and to modulate intracellular effectors associated with oxidative stress (e.g. heme oxygenase), neuronal energy homeostasis (e.g. AMP kinase), program cell death (i.e. AIF) and longevity (i.e. sirtuins). This article summarizes the most recent findings on mechanisms of action involved in the protective effects of this multi target polyphenol, and discusses its possible roles in the prevention of various age-related neurological disorders. This article is part of a Special Issue entitled: Resveratrol: Challenges in translating pre-clinical findings to improved patient outcomes.

Glutamatergic signaling and low prodynorphin expression are associated with intact memory and reduced anxiety in rat models of healthy aging

The LOU/C/Jall (LOU) rat strain is considered a model of healthy aging due to its increased longevity, maintenance of stable body weight (BW) throughout life and low incidence of age-related diseases. However, aging LOU rat cognitive and anxiety status has yet to be investigated. In the present study, male and female LOU rat cognitive performances (6-42 months) were assessed using novel object recognition and Morris Water Maze tasks. Recognition memory remained intact in all LOU rats up to 42 months of age. As for spatial memory, old LOU rat performed similarly as young animals for learning acquisition, reversal learning, and retention. While LOU rat BW remained stable despite aging, 20-month-old ad-libitum-fed (OAL) male Sprague Dawley rats become obese. We determined if long-term caloric restriction (LTCR) prevents age-related BW increase and cognitive deficits in this rat strain, as observed in the obesity-resistant LOU rats. Compared to young animals, recognition memory was impaired in OAL but intact in 20-month-old calorie-restricted (OCR) rats. Similarly, OAL spatial learning acquisition was impaired but LTCR prevented the deficits. Exacerbated stress responses may favor age-related cognitive decline. In the elevated plus maze and open field tasks, LOU and OCR rats exhibited high levels of exploratory activity whereas OAL rats displayed anxious behaviors. Expression of prodynorphin (Pdyn), an endogenous peptide involved in stress-related memory impairments, was increased in the hippocampus of OAL rats. Group 1 metabotropic glutamate receptor 5 and immediate early genes Homer 1a and Arc expression, both associated with successful cognitive aging, were unaltered in aging LOU rats but lower in OAL than OCR rats. Altogether, our results, supported by principal component analysis and correlation matrix, suggest that intact memory and low anxiety are associated with glutamatergic signaling and low Pdyn expression in the hippocampus of non-obese aging rats.

Possible role of dynorphins in Alzheimer's disease and age-related cognitive deficits

BACKGROUND/AIMS

Expression of dynorphin, an endogenous opioid peptide, increases with age and has been associated with cognitive deficits in rodents. Elevated dynorphin levels have been reported in postmortem samples from Alzheimer's disease (AD) patients, and prodynorphin (PDYN) gene polymorphisms might be linked to cognitive function in the elderly. Activation of κ-opioid receptors by dynorphins has been associated with stress-related memory impairments. Interestingly, these peptides can also modulate glutamate neurotransmission and may affect synaptic plasticity underlying memory formation. N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazol-propionate (AMPA) ionotropic glutamate receptor levels generally decrease with aging, and their function is impaired in AD.

METHODS

Here, we compared the impact of aging on ionotropic glutamate receptor levels in the hippocampal formation of wild-type (WT) and Pdyn knock-out (KO) mice.

RESULTS

We observed a significant reduction in GluR1 and GluR2 AMPA receptor subunits in the hippocampal formation of 18- to 25-month-old WT mice in comparison with 6-month-old mice. Conversely, the GluR1 protein level was maintained in old Pdyn KO mice, and the NMDA NR2B subunit level was increased by 42% when compared to old WT animals.

CONCLUSIONS

These results suggest that elevated dynorphin expression occurring during aging and AD may mediate cognitive deficits by altering the glutamatergic system integrity.

Circulating miRNAs as sensitive and specific biomarkers for the diagnosis and monitoring of human diseases: promises and challenges

The regulation and modulation of gene expression has been a central focus of modern biomedical research ever since the first molecular elucidation of DNA. The cellular mechanisms by which genes are expressed and repressed hold valuable insight for maintaining tissue homeostasis or conversely provide mechanistic understanding of disease progression. Hence, the discovery of the first miRNA in humans roughly a decade ago profoundly shook the previously established dogmas of gene regulation. Since, these small RNAs of around 20 nucleotides have unquestionably influenced almost every area of medical research. This momentum has now spread to the clinical arena. Hundreds of papers have already been published shedding light on the mechanisms of action of miRNAs, their profound stability in almost every bodily fluid and relating their presence to disease state and severity of disease progression. In this review, we explore the diagnostic potential of miRNAs in the clinical laboratory with a focus on studies reporting the detection of miRNAs in blood and urine for investigation of human disease. Sensitivities, specificities, areas under the curve, group descriptions and miRNAs of interest for 69 studies covering a broad range of diseases are provided. We discuss the practicality of miRNAs in the screening, diagnosis and prognosis of a range of pathologies. Characteristics and pitfalls of miRNA detection in blood are also discussed. The topics covered here are pertinent in the design of future miRNA-based detection strategies for use in clinical biochemistry laboratory settings.

Immune marker CD68 correlates with cognitive impairment in normally aged rats

The relationship between heightened neuroinflammation and cognitive decline in the normally aged brain is still debatable, as most data are derived from insult-related models. Accordingly, the aim of the current study was to determine whether a link could be established for 2 immune markers at the post-transcriptional level; CD68 and MHC-II, in a normally aged (24-month-old) rat population discriminated for their learning abilities. Using the Morris Water Maze (MWM) task, aged rats were divided into aged learning-impaired (AI) or -unimpaired (AU) groups. Western immunoblots of hippocampal tissue revealed a significant increase of CD68 in AI rats compared to the AU group. Moreover, up-regulated CD68 expression correlated with increased latency times in the MWM task. Immunofluorescence for CD68 revealed intense staining in the white matter regions and CA3 subregion of the hippocampus in the AI group. Despite expression of MHC-II in the AI group, no correlation was found. Overall, these data suggest that CD68 could play a role associated with cognitive decline in a subgroup of the normally aged population.

Group 1 metabotropic glutamate receptor function and its regulation of learning and memory in the aging brain

Normal aging is generally characterized by a slow decline of cognitive abilities albeit with marked individual differences. Several animal models have been studied to explore the molecular and cellular mechanisms underlying this phenomenon. The excitatory neurotransmitter glutamate and its receptors have been closely linked to spatial learning and hippocampus-dependent memory processes. For decades, ionotropic glutamate receptors have been known to play a critical role in synaptic plasticity, a form of adaptation regulating memory formation. Over the past 10 years, several groups have shown the importance of group 1 metabotropic glutamate receptor (mGluR) in successful cognitive aging. These G-protein-coupled receptors are enriched in the hippocampal formation and interact physically with other proteins in the membrane including glutamate ionotropic receptors. Synaptic plasticity is crucial to maintain cognitive abilities and long-term depression (LTD) induced by group 1 mGluR activation, which has been linked to memory in the aging brain. The translation and synthesis of proteins by mGluR-LTD modulate ionotropic receptor trafficking and expression of immediate early genes related to cognition. Fragile X syndrome, a genetic form of autism characterized by memory deficits, has been associated to mGluR receptor malfunction and aberrant activation of its downstream signaling pathways. Dysfunction of mGluR could also be involved in neurodegenerative disorders like Alzheimer’s disease (AD). Indeed, beta-amyloid, the main component of insoluble senile plaques and one of the hallmarks of AD, occludes mGluR-dependent LTD leading to diminished functional synapses. This review highlights recent findings regarding mGluR signaling, related synaptic plasticity, and their potential involvement in normal aging and neurological disorders.

Determination of melamine, ammeline, ammelide and cyanuric acid in infant formula purchased in Canada by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry-based isotope dilution method was developed for the analysis of the triazine compounds melamine (MEL), ammeline (AMN), ammelide (AMD) and cyanuric acid (CYA) in infant formula samples purchased in Canada in 2008 for the purpose of a combined exposure and risk assessment. Infant formula samples were extracted with 1:1 acetonitrile-water, cleaned up on disposable ion-exchange solid-phase extraction cartridges, and analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. MEL and CYA were detected in almost all infant formula products: the highest concentrations observed were 0.32 mg kg(-1) MEL and 0.45 mg kg(-1) CYA. Samples that were relatively high in MEL in this survey tended to be low in CYA, and vice versa. Concentrations of AMN and AMD were very low in all samples. The total of MEL-related compounds (sum of all four analytes) in all samples was below the interim standard of 0.5 mg kg(-1) for infant formula products established by Health Canada.

Development of a geometrically accurate imaging protocol at 3 Tesla MRI for stereotactic radiosurgery treatment planning

The purpose of this study is to develop a geometrically accurate imaging protocol at 3 T magnetic resonance imaging (MRI) for stereotactic radiosurgery (SRS) treatment planning. In order to achieve this purpose, a methodology is developed to investigate the geometric accuracy and stability of 3 T MRI for SRS in phantom and patient evaluations. Forty patients were enrolled on a prospective clinical trial. After frame placement prior to SRS, each patient underwent 3 T MRI after 1.5 T MRI and CT. MR imaging protocols included a T1-weighted gradient echo sequence and a T2-weighted spin echo sequence. Phantom imaging was performed on 3 T prior to patient imaging using the same set-up and imaging protocols. Geometric accuracy in patients and phantoms yielded comparable results for external fiducial reference deviations and internal landmarks between 3 T and 1.5 T MRI (mean ≤ 0.6 mm; standard deviation ≤ 0.3 mm). Mean stereotactic reference deviations between phantoms and patients correlated well (T1: R = 0.79; T2: R = 0.84). Statistical process control analysis on phantom QA data demonstrated the stability of our SRS imaging protocols, where the geometric accuracy of the 3 T SRS imaging protocol is operating within the appropriate tolerance. Our data provide evidence supporting the spatial validity of 3 T MRI for targeting SRS under imaging conditions investigated. We have developed a systematic approach to achieve confidence on the geometric integrity of a given imaging system/technique for clinical integration in SRS application.

Clinical outcomes of adult patients with primary intracranial germinomas treated with low-dose craniospinal radiotherapy and local boost

The authors document the long term follow up of adult patients with histologically proven primary intracranial germinoma treated with radiotherapy alone using a craniospinal with local boost technique. A retrospective review was conducted on adults diagnosed with intracranial germinoma who received radiotherapy at the Princess Margaret Hospital, Toronto from 1990 to 2007. The study group consisted of 10 males with a median age of 24.1 years. All patients received radiotherapy alone using craniospinal radiotherapy and local boost. There were 10 patients (all male) with a median follow up of 10.9 years (range 2.2-18.9 years). At date of last follow up all patients were still alive, none with relapsed disease. Seven of ten patients (70%) had panhypopituitarianism prior to commencing radiotherapy and hormonal function was not affected in those with an intact pituitary axis. There was no reported cognitive decline in the treated cohort. For adult intracranial germinomas, with long term follow up, low-dose craniospinal radiotherapy with in field boost is highly effective with minimal morbidity.