Reopening Oral Health Services during the COVID-19 Pandemic through a Knowledge Exchange Coalition.

BACKGROUND: The COVID-19 novel coronavirus closed oral health care in Nova Scotia (NS) Canada in March 2020. Preparing for a phased reopening, a knowledge exchange coalition (representing government, academia, hospitals, oral health professions, and regulators) developed return-to-work (RTW) guidelines detailing the augmentation of standard practices to ensure safety for patients, oral health care providers (OHPs), and the community. Using online surveys, this study explored the influence of the RTW guidelines and related education on registered NS OHPs during a phased return to work. METHODS: Dissemination of R2W guidelines included website or email communiques and interdisciplinary education webinars that coincided with 2 RTW phases approved by the government. Aligned with each phase, all registered dentists, dental hygienists, and dental assistants were invited to complete an online survey to gauge the influence of the coalition-sponsored education and RTW guidelines, confidence, preparedness, and personal protective equipment use before and after the pandemic. RESULTS: Three coalition-sponsored multidisciplinary webinars hosted 3541 attendees prior to RTW. The response to survey 1 was 41% (881/2156) and to survey 2 was 26% (571/2177) of registrants. Survey 1 (82%) and survey 2 (89%) respondents "agreed/strongly agreed" that R2W guidelines were a primary source for guiding return to practice, and most were confident with education received and had the skills needed to effectively treat patients during the COVID-19 pandemic. Confidence and preparedness improved in survey 2. Gowns/lab coat use for aerosol-generating procedures increased from 26% to 93%, and the use of full face shields rose from 6% to 93% during the pandemic. CONCLUSIONS: A multistakeholder coalition was effective in establishing and communicating comprehensive guidelines and web-based education to ensure unified reintegration of oral health services in NS during a pandemic. This multiorganizational cooperation lay the foundation for responses to subsequent waves of COVID-19 and may serve as an example for collaboratively responding to future public health threats in other settings. KNOWLEDGE TRANSFER STATEMENT: The return-to-work strategy that was developed, disseminated, and assessed through this COVID-19 knowledge exchange coalition will benefit oral health practitioners, professional regulators, government policy makers, and researchers in future pandemic planning.

Neuropsychological outcome following thalamic stroke in adolescence: an identical twin comparison.

Objective: Medial thalamic stroke in adults commonly results in severe learning and memory impairments and executive dysfunction, particularly during the acute phase. However, there is limited research on the cognitive recovery from thalamic stroke in physically healthy adolescents. This study aimed to fill this gap in the literature by utilizing a monozygotic twin control to investigate the neuropsychological outcomes of bilateral thalamic stroke in adolescence. Method: We evaluated an otherwise healthy 17-year-old male with a history of premature birth, developmental delay, and learning disability 2 and 7 months after he sustained a bilateral medial/anterior thalamic stroke of unknown etiology. His identical twin brother served as a case control. Results: The patient presented with improvements in many cognitive skills between assessments, most notably processing speed. Despite some mild improvement, however, he presented with significant deficits in fine motor speed/coordination, spatial perception, and rapid naming. Additionally, he exhibited persistent, severe deficits in verbal learning and memory. Relative sparing of executive functions (i.e., planning and set-shifting) and attention on standardized measures in this case may be explained by good underlying health, limited extra-thalamic damage, and/or recovery of function. The effects of thalamic injury resulted in minimal adaptive dysfunction or deterrence from academic or athletic success for the presented case. Conclusions: These results suggest risk for deficits in encoding of new verbal information following bilateral thalamic stroke in adolescence, as well as risk for persistent cognitive deficits despite initial improvements. This is consistent with descriptions of anterograde memory impairments in adults with similar lesions.

Working memory contributes to the encoding of object location associations: Support for a 3-part model of object location memory.

A recent model by Postma and colleagues posits that the encoding of object location associations (OLAs) requires the coordination of several cognitive processes mediated by ventral (object perception) and dorsal (spatial perception) visual pathways as well as the hippocampus (feature binding) [1]. Within this model, frontoparietal network recruitment is believed to contribute to both the spatial processing and working memory task demands. The current study used functional magnetic resonance imaging (fMRI) to test each step of this model in 15 participants who encoded OLAs and performed standard n-back tasks. As expected, object processing resulted in activation of the ventral visual stream. Object in location processing resulted in activation of both the ventral and dorsal visual streams as well as a lateral frontoparietal network. This condition was also the only one to result in medial temporal lobe activation, supporting its role in associative learning. A conjunction analysis revealed areas of shared activation between the working memory and object in location phase within the lateral frontoparietal network, anterior insula, and basal ganglia; consistent with prior working memory literature. Overall, findings support Postma and colleague's model and provide clear evidence for the role of working memory during OLA encoding.

Antiphospholipid antibody-mediated effects in an arterial model of thrombosis are dependent on Toll-like receptor 4.

Patients with antiphospholipid syndrome (APS) produce antiphospholipid antibodies (aPL) and develop vascular thrombosis that may occur in large or small vessels in the arterial or venous beds. On the other hand, many individuals produce aPL and yet never develop thrombotic events. Toll-like receptor 4 (TLR4) appears to be necessary for aPL-mediated prothrombotic effects in venous and microvascular models of thrombosis, but its role in arterial thrombosis has not been studied. Here, we propose that aPL alone are insufficient to cause thrombotic events in an arterial model of APS, and that a concomitant trigger of innate immunity (e.g. TLR4 activation) is required. We show specifically that anti-ß2-glycoprotein I (anti-ß2GPI) antibodies, a subset of aPL, accelerated thrombus formation in C57BL/6 wild-type, but not TLR4-deficient, mice in a ferric chloride-induced carotid artery injury model. These aPL bound to arterial and venous endothelial cells, particularly in the presence of ß2GPI, and to human TLR4 by enzyme-linked immunoassay. Arterial endothelium from aPL-treated mice had enhanced leukocyte adhesion, compared to control IgG-treated mice. In addition, aPL treatment of mice enhanced expression of tissue factor (TF) in leukocytes induced by the TLR4 ligand lipopolysaccharide (LPS). aPL also enhanced LPS-induced TF expression in human leukocytes in vitro. Our findings support a mechanism in which aPL enhance TF expression by leukocytes, as well as augment adhesion of leukocytes to the arterial endothelium. The activation of TLR4 in aPL-positive individuals may be required to trigger thrombotic events.

Transcranial direct current stimulation modulates spatial memory in cognitively intact adults.

Two forms of spatial processing are involved in object location memory. Coordinate processing uses a fine-grained code to provide exact knowledge for the location and is believed dependent on the right posterior parietal cortex (PPC). Categorical processing relies on spatial relationships between objects and is believed dependent on the left PPC. We used transcranial direct current stimulation (tDCS) to test these brain-behavior relationships during the encoding and subsequent recall of object location associations. Twelve right-handed, healthy young participants received 20 min of tDCS (2mA) during three separate sessions. Stimulation delivery was counterbalanced across participants and sessions and included anodal ("excitatory") stimulation of right PPC with concurrent left PPC cathodal ("inhibitory") stimulation (R+L-), the reverse montage (R-L+), and sham stimulation. Participants completed different versions of the Object Location Touchscreen Task (OLTT) during each session, which assesses coordinate (recall of the location without the environment) and categorical processing (recall of the location with the environment). Encoding occurred during the last 5 min of stimulation, while the delay phase occurred 15 min after stimulation. Participants performed more accurately during the coordinate phase following R-L+ stimulation when compared to R+L- performance. Categorical performance was not significantly affected by stimulation. Findings suggest two possibilities that will be examined in future studies with larger sample sizes: (1) The R-L+ facilitates left-hemisphere dominant categorical processing, the benefits of which persists even when environmental details are absent, possibly due to increased mental imagery; (2) Cathodal stimulation decreased spurious neuronal noise thereby allowing for more efficient processing by the "critical" neuronal populations in the right PPC.

A two-part preliminary investigation of encoding-related activation changes after moderate to severe traumatic brain injury: hyperactivation, repetition suppression, and the role of the prefrontal cortex.

Traumatic brain injury (TBI) survivors typically exhibit significant learning and memory deficits and also frequently demonstrate hyperactivation during functional magnetic resonance imaging (fMRI) tasks involving working memory encoding and maintenance. However, it remains unclear whether the hyperactivation observed during such working memory tasks is also present during long-term memory encoding. The preliminary experiments presented here were designed to examine this question. In Experiment 1, 7 healthy controls (HC) and 7 patients with moderate to severe TBI encoded ecologically relevant object location associations (OLA) while undergoing fMRI and then completed a memory test outside of the fMRI environment. fMRI data analysis included only the correctly encoded trials and revealed hyperactivation in the TBI relative to HC group in regions critical for OLA encoding, including bilateral dorsal and ventral visual processing areas, bilateral frontoparietal working memory network regions, and the left medial temporal lobe. There was also an incidental finding that this hyperactivation persisted after multiple exposures to the same stimulus, which may indicate an attenuated repetition suppression effect that could ultimately contribute to cognitive fatigue and inefficient memory encoding after TBI. Experiment 2 directly assessed repetition suppression in some of the same HC and TBI participants. During early encoding trials, the TBI group showed large areas of hyperactivation in the right prefrontal cortex and bilateral posterior parietal cortices relative to the HC. Following additional exposure to these stimuli, the TBI group showed repetition suppression in visual and spatial processing regions, but continued to show hyperactivation in the right dorsolateral prefrontal cortex. Findings from these preliminary studies may reflect that increased reliance on cognitive control mechanisms following TBI extends to memory encoding.

RBANS memory indices are related to medial temporal lobe volumetrics in healthy older adults and those with mild cognitive impairment.

The current study (i) determined whether NeuroQuant(®) volumetrics are reflective of differences in medial temporal lobe (MTL) volumes between healthy older adults and those with mild cognitive impairment (MCI) and (ii) examined the relationship between RBANS indices and MTL volumes. Forty-three healthy older adults and 57 MCI patients completed the RBANS and underwent structural MRI. Hippocampal and inferior lateral ventricle (ILV) volumes were obtained using NeuroQuant(®). Results revealed significantly smaller hippocampal and larger ILV volumes in MCI patients. MTL volumes were significantly related to the RBANS Immediate and Delayed Memory and Language indices but not the Attention or Visuoconstruction indices; findings that demonstrate anatomical specificity. Following discriminant function analysis, we calculated a cutpoint that may prove clinically useful for integrating MTL volumes into the diagnosis of MCI. These findings demonstrate the potential clinical utility of NeuroQuant(®) and are the first to document the relationship between RBANS indices and MTL volumes.

Cognitive rehabilitation of memory for mild cognitive impairment: a methodological review and model for future research.

Several recent reviews have suggested that cognitive rehabilitation may hold promise in the treatment of memory deficits experienced by patients with mild cognitive impairment. In contrast to the previous reviews that mainly focused on outcome, the current review examines key methodological challenges that are critical for designing and interpreting research studies and translating results into clinical practice. Using methodological details from 36 studies, we first examine diagnostic variability and how the use of cutoffs may bias samples toward more severely impaired patients. Second, the strengths and limitations of several common rehabilitative techniques are discussed. Half of the reviewed studies used a multi-technique approach that precludes the causal attribution between any specific technique and subsequent improvement. Third, there is a clear need to examine the dose-response relationship since this information was strikingly absent from most studies. Fourth, outcome measures varied widely and frequently depended on neuropsychological tests with little theoretical justification or ecological relevance. Fifth, we discuss how the variability in each of these other four areas complicates efforts to examine training generalization. Overall, future studies should place greater emphasis on ecologically relevant treatment approaches and outcome measures and we propose a hierarchical model that may aid in this pursuit.

Neuropsychiatric disease relevance of circulating anti-NMDA receptor autoantibodies depends on blood-brain barrier integrity.

In 2007, a multifaceted syndrome, associated with anti-NMDA receptor autoantibodies (NMDAR-AB) of immunoglobulin-G isotype, has been described, which variably consists of psychosis, epilepsy, cognitive decline and extrapyramidal symptoms. Prevalence and significance of NMDAR-AB in complex neuropsychiatric disease versus health, however, have remained unclear. We tested sera of 2817 subjects (1325 healthy, 1081 schizophrenic, 263 Parkinson and 148 affective-disorder subjects) for presence of NMDAR-AB, conducted a genome-wide genetic association study, comparing AB carriers versus non-carriers, and assessed their influenza AB status. For mechanistic insight and documentation of AB functionality, in vivo experiments involving mice with deficient blood-brain barrier (ApoE(-/-)) and in vitro endocytosis assays in primary cortical neurons were performed. In 10.5% of subjects, NMDAR-AB (NR1 subunit) of any immunoglobulin isotype were detected, with no difference in seroprevalence, titer or in vitro functionality between patients and healthy controls. Administration of extracted human serum to mice influenced basal and MK-801-induced activity in the open field only in ApoE(-/-) mice injected with NMDAR-AB-positive serum but not in respective controls. Seropositive schizophrenic patients with a history of neurotrauma or birth complications, indicating an at least temporarily compromised blood-brain barrier, had more neurological abnormalities than seronegative patients with comparable history. A common genetic variant (rs524991, P=6.15E-08) as well as past influenza A (P=0.024) or B (P=0.006) infection were identified as predisposing factors for NMDAR-AB seropositivity. The >10% overall seroprevalence of NMDAR-AB of both healthy individuals and patients is unexpectedly high. Clinical significance, however, apparently depends on association with past or present perturbations of blood-brain barrier function.