Emotional facial expression and perioral motor functions of the human auditory cortex.

OBJECTIVE: We investigated the role of transverse temporal gyrus and adjacent cortex (TTG+) in facial expressions and perioral movements. METHODS: In 31 patients undergoing stereo-electroencephalography monitoring, we describe behavioral responses elicited by electrical stimulation within the TTG+. Task-induced high-gamma modulation (HGM), auditory evoked responses, and resting-state connectivity were used to investigate the cortical sites having different types of responses on electrical stimulation. RESULTS: Changes in facial expressions and perioral movements were elicited on electrical stimulation within TTG+ in 9 (29%) and 10 (32%) patients, respectively, in addition to the more common language responses (naming interruptions, auditory hallucinations, paraphasic errors). All functional sites showed auditory task induced HGM and evoked responses validating their location within the auditory cortex, however, motor sites showed lower peak amplitudes and longer peak latencies compared to language sites. Significant first-degree connections for motor sites included precentral, anterior cingulate, parahippocampal, and anterior insular gyri, whereas those for language sites included posterior superior temporal, posterior middle temporal, inferior frontal, supramarginal, and angular gyri. CONCLUSIONS: Multimodal data suggests that TTG+ may participate in auditory-motor integration. SIGNIFICANCE: TTG+ likely participates in facial expressions in response to emotional cues during an auditory discourse.

Accounting for the increasing benefits from scarce ecosystems.

As people get richer, and ecosystem services scarcer, policy-relevant estimates of ecosystem value must rise.

Early Identification of Candidates for Epilepsy Surgery: A Multicenter, Machine Learning, Prospective Validation Study.

BACKGROUND AND OBJECTIVES: Epilepsy surgery is often delayed. We previously developed machine learning (ML) models to identify candidates for resective epilepsy surgery earlier in the disease course. In this study, we report the prospective validation. METHODS: In this multicenter, prospective, longitudinal cohort study, random forest models were validated at a pediatric epilepsy center consisting of 2 hospitals and 14 outpatient neurology clinic sites and an adult epilepsy center with 2 hospitals and 27 outpatient neurology clinic sites. The models used neurology visit notes, EEG and MRI reports, visit patterns, hospitalizations, and medication, laboratory, and procedure orders to identify candidates for surgery. The models were trained on historical data up to May 10, 2019. Patients with an ICD-10 diagnosis of epilepsy who visited from May 11, 2019, to May 10, 2020, were screened by the algorithm and assigned surgical candidacy scores. The primary outcome was area under the curve (AUC), which was calculated by comparing scores from patients who underwent epilepsy surgery before November 10, 2020, against scores from nonsurgical patients. Nonsurgical patients' charts were reviewed to determine whether patients with high scores were more likely to be missed surgical candidates. Delay to surgery was defined as the time between the first visit that a surgical candidate was identified by the algorithm and the date of the surgery. RESULTS: A total of 5,285 pediatric and 5,782 adult patients were included to train the ML algorithms. During the study period, 41 children and 23 adults underwent resective epilepsy surgery. In the pediatric cohort, AUC was 0.91 (95% CI 0.87-0.94), positive predictive value (PPV) was 0.08 (0.05-0.10), and negative predictive value (NPV) was 1.00 (0.99-1.00). In the adult cohort, AUC was 0.91 (0.86-0.97), PPV was 0.07 (0.04-0.11), and NPV was 1.00 (0.99-1.00). The models first identified patients at a median of 2.1 years (interquartile range [IQR]: 1.2-4.9 years, maximum: 11.1 years) before their surgery and 1.3 years (IQR: 0.3-4.0 years, maximum: 10.1 years) before their presurgical evaluations. DISCUSSION: ML algorithms can identify surgical candidates earlier in the disease course. Even at specialized epilepsy centers, there is room to shorten the time to surgery. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that a machine learning algorithm can accurately distinguish patients with epilepsy who require resective surgery from those who do not.

Determining Susceptibility and Potential Mediators of Resistance for the Novel Polymyxin Derivative, SPR206, in Acinetobacter baumannii.

With the increase in carbapenem-resistant A. baumannii (CRAB) infections, there has been a resurgence in the use of polymyxins, specifically colistin (COL). Since the reintroduction of COL-based regimens in treating CRAB infections, several COL-resistant A. baumannii isolates have been identified, with the mechanism of resistance heavily linked with the loss of the lipopolysaccharide (LPS) layer of the bacterial outer membrane through mutations in lpxACD genes or the pmrCAB operon. SPR206, a novel polymyxin derivative, has exhibited robust activity against multidrug-resistant (MDR) A. baumannii. However, there is a dearth of knowledge regarding its efficacy in comparison with other A. baumannii-active therapeutics and whether traditional polymyxin (COL) mediators of A. baumannii resistance also translate to reduced SPR206 activity. Here, we conducted susceptibility testing using broth microdilution on 30 A. baumannii isolates (17 COL-resistant and 27 CRAB), selected 14 COL-resistant isolates for genomic sequencing analysis, and performed time-kill analyses on four COL-resistant isolates. In susceptibility testing, SPR206 demonstrated a lower range of minimum inhibitory concentrations (MICs) compared with COL, with a four-fold difference observed in MIC50 values. Mutations in lpxACD and/or pmrA and pmrB genes were detected in each of the 14 COL-resistant isolates; however, SPR206 maintained MICs ≤ 2 mg/L for 9/14 (64%) of the isolates. Finally, SPR206-based combination regimens exhibited increased synergistic and bactericidal activity compared with COL-based combination regimens irrespective of the multiple resistance genes detected. The results of this study highlight the potential utility of SPR206 in the treatment of COL-resistant A. baumannii infections.

Filifactor alocis enhances survival of Porphyromonas gingivalis W83 in response to H2 O2 -induced stress.

A dysbiotic microbial community whose members have specific/synergistic functions that are modulated by environmental conditions, can disturb homeostasis in the subgingival space leading to destructive inflammation, plays a role in the progression of periodontitis. Filifactor alocis, a gram-positive, anaerobic bacterium, is a newly recognized microbe that shows a strong correlation with periodontal disease. Our previous observations suggested F. alocis to be more resistant to oxidative stress compared to Porphyromonas gingivalis. The objective of this study is to further determine if F. alocis, because of its increased resistance to oxidative stress, can affect the survival of other 'established' periodontal pathogens under environmental stress conditions typical of the periodontal pocket. Here, we have shown that via their interaction, F. alocis protects P. gingivalis W83 under H2 O2 -induced oxidative stress conditions. Transcriptional profiling of the interaction of F. alocis and P. gingivalis in the presence of H2 O2 -induced stress revealed the modulation of several genes, including those with ABC transporter and other cellular functions. The ABC transporter operon (PG0682-PG0685) of P. gingivalis was not significant to its enhanced survival when cocultured with F. alocis under H2 O2 -induced oxidative stress. In F. alocis, one of the most highly up-regulated operons (FA0894-FA0897) is predicted to encode a putative manganese ABC transporter, which in other bacteria can play an essential role in oxidative stress protection. Collectively, the results may indicate that F. alocis could likely stabilize the microbial community in the inflammatory microenvironment of the periodontal pocket by reducing the oxidative environment. This strategy could be vital to the survival of other pathogens, such as P. gingivalis, and its ability to adapt and persist in the periodontal pocket.

Reporting standard for describing first responder systems, smartphone alerting systems, and AED networks.

Standardized reporting of data is crucial for out-of-hospital cardiac arrest (OHCA) research. While the implementation of first responder systems dispatching volunteers to OHCA is encouraged, there is currently no uniform reporting standard for describing these systems. A steering committee established a literature search to identify experts in smartphone alerting systems. These international experts were invited to a conference held in Hinterzarten, Germany, with 40 researchers from 13 countries in attendance. Prior to the conference, participants submitted proposals for parameters to be included in the reporting standard. The conference comprised five workshops covering different aspects of smartphone alerting systems. Proposed parameters were discussed, clarified, and consensus was achieved using the Nominal Group Technique. Participants voted in a modified Delphi approach on including each category as a core or supplementary element in the reporting standard. Results were presented, and a writing group developed definitions for all categories and items, which were sent to participants for revision and final voting using LimeSurvey web-based software. The resulting reporting standard consists of 68 core items and 21 supplementary items grouped into five topics (first responder system, first responder network, technology/algorithm/strategies, reporting data, and automated external defibrillators (AED)). This proposed reporting standard generated by an expert opinion group fills the gap in describing first responder systems. Its adoption in future research will facilitate comparison of systems and research outcomes, enhancing the transfer of scientific findings to clinical practice.

Developmental epileptic encephalopathy in DLG4-related synaptopathy.

OBJECTIVE: The postsynaptic density protein of excitatory neurons PSD-95 is encoded by discs large MAGUK scaffold protein 4 (DLG4), de novo pathogenic variants of which lead to DLG4-related synaptopathy. The major clinical features are developmental delay, intellectual disability (ID), hypotonia, sleep disturbances, movement disorders, and epilepsy. Even though epilepsy is present in 50% of the individuals, it has not been investigated in detail. We describe here the phenotypic spectrum of epilepsy and associated comorbidities in patients with DLG4-related synaptopathy. METHODS: We included 35 individuals with a DLG4 variant and epilepsy as part of a multicenter study. The DLG4 variants were detected by the referring laboratories. The degree of ID, hypotonia, developmental delay, and motor disturbances were evaluated by the referring clinician. Data on awake and sleep electroencephalography (EEG) and/or video-polygraphy and brain magnetic resonance imaging were collected. Antiseizure medication response was retrospectively assessed by the referring clinician. RESULTS: A large variety of seizure types was reported, although focal seizures were the most common. Encephalopathy related to status epilepticus during slow-wave sleep (ESES)/developmental epileptic encephalopathy with spike-wave activation during sleep (DEE-SWAS) was diagnosed in >25% of the individuals. All but one individual presented with neurodevelopmental delay. Regression in verbal and/or motor domains was observed in all individuals who suffered from ESES/DEE-SWAS, as well as some who did not. We could not identify a clear genotype-phenotype relationship even between individuals with the same DLG4 variants. SIGNIFICANCE: Our study shows that a subgroup of individuals with DLG4-related synaptopathy have DEE, and approximately one fourth of them have ESES/DEE-SWAS. Our study confirms DEE as part of the DLG4-related phenotypic spectrum. Occurrence of ESES/DEE-SWAS in DLG4-related synaptopathy requires proper investigation with sleep EEG.

Virtual lesions in MEG reveal increasing vulnerability of the language network from early childhood through adolescence.

In childhood, language outcomes following brain injury are inversely related to age. Neuroimaging findings suggest that extensive representation and/or topological redundancy may confer the pediatric advantage. Here, we assess whole brain and language network resilience using in silico attacks, for 85 children participating in a magnetoencephalography (MEG) study. Nodes are targeted based on eigenvector centrality, betweenness centrality, or at random. The size of each connected component is assessed after iterated node removal; the percolation point, or moment of dis-integration, is defined as the first instance where the second largest component peaks in size. To overcome known effects of fixed thresholding on subsequent graph and resilience analyses, we study percolation across all possible network densities, within a Functional Data Analysis (FDA) framework. We observe age-related increases in vulnerability for random and betweenness centrality-based attacks for whole-brain and stories networks (adjusted-p < 0.05). Here we show that changes in topology underlie increasing language network vulnerability in development.

Inhibition of ß-lactamase function by de novo designed peptide.

Antimicrobial resistance is a great public health concern that is now described as a "silent pandemic". The global burden of antimicrobial resistance requires new antibacterial treatments, especially for the most challenging multidrug-resistant bacteria. There are various mechanisms by which bacteria develop antimicrobial resistance including expression of ß-lactamase enzymes, overexpression of efflux pumps, reduced cell permeability through downregulation of porins required for ß-lactam entry, or modifications in penicillin-binding proteins. Inactivation of the ß-lactam antibiotics by ß-lactamase enzymes is the most common mechanism of bacterial resistance to these agents. Although several effective small-molecule inhibitors of ß-lactamases such as clavulanic acid and avibactam are clinically available, they act only on selected class A, C, and some class D enzymes. Currently, none of the clinically approved inhibitors can effectively inhibit Class B metallo-ß-lactamases. Additionally, there is increased resistance to these inhibitors reported in several bacteria. The objective of this study is to use the Resonant Recognition Model (RRM), as a novel strategy to inhibit/modulate specific antimicrobial resistance targets. The RRM is a bio-physical approach that analyzes the distribution of energies of free electrons and posits that there is a significant correlation between the spectra of this energy distribution and related protein biological activity. In this study, we have used the RRM concept to evaluate the structure-function properties of a group of 22 ß-lactamase proteins and designed 30-mer peptides with the desired RRM spectral periodicities (frequencies) to function as ß-lactamase inhibitors. In contrast to the controls, our results indicate 100% inhibition of the class A ß-lactamases from Escherichia coli and Enterobacter cloacae. Taken together, the RRM model can likely be utilized as a promising approach to design ß-lactamase inhibitors for any specific class. This may open a new direction to combat antimicrobial resistance.

Age-related increases in right hemisphere support for prosodic processing in children.

Language comprehension is a complex process involving an extensive brain network. Brain regions responsible for prosodic processing have been studied in adults; however, much less is known about the neural bases of prosodic processing in children. Using magnetoencephalography (MEG), we mapped regions supporting speech envelope tracking (a marker of prosodic processing) in 80 typically developing children, ages 4-18 years, completing a stories listening paradigm. Neuromagnetic signals coherent with the speech envelope were localized using dynamic imaging of coherent sources (DICS). Across the group, we observed coherence in bilateral perisylvian cortex. We observed age-related increases in coherence to the speech envelope in the right superior temporal gyrus (r = 0.31, df = 78, p = 0.0047) and primary auditory cortex (r = 0.27, df = 78, p = 0.016); age-related decreases in coherence to the speech envelope were observed in the left superior temporal gyrus (r = - 0.25, df = 78, p = 0.026). This pattern may indicate a refinement of the networks responsible for prosodic processing during development, where language areas in the right hemisphere become increasingly specialized for prosodic processing. Altogether, these results reveal a distinct neurodevelopmental trajectory for the processing of prosodic cues, highlighting the presence of supportive language functions in the right hemisphere. Findings from this dataset of typically developing children may serve as a potential reference timeline for assessing children with neurodevelopmental hearing and speech disorders.

Neuropsychological outcomes after epilepsy surgery: A comparison of stereo electroencephalography and subdural electrodes.

BACKGROUND AND PURPOSE: We analyzed the association of neuropsychological outcomes after epilepsy surgery with the intracranial electrode type (stereo electroencephalography [SEEG] and subdural electrodes [SDE]), and electrical stimulation mapping (ESM) of speech/language. METHODS: Drug-resistant epilepsy patients who underwent comprehensive neuropsychological evaluation before and 1 year after epilepsy surgery were included. SEEG and SDE subgroups were matched by age, handedness, operated hemisphere, and seizure freedom. Postsurgical neuropsychological outcomes (adjusted for presurgical scores) and reliable change indices were analyzed as functions of electrode type and ESM. RESULTS: Ninety-nine patients aged 6-29 years were included with similar surgical resection/ablation volumes in the SEEG and SDE subgroups. Most of the neuropsychological outcomes were comparable between SEEG and SDE subgroups; however, Working Memory and Processing Speed were significantly improved in the SEEG subgroup. Undergoing language ESM was associated with significant improvements in Spelling, Letter-Word Identification, Vocabulary, Verbal Comprehension, Verbal Learning, and Story Memory scores, but a decline in Calculation scores. CONCLUSIONS: Intracranial evaluations with SEEG and SDE are comparable in terms of long-term postsurgical neuropsychological outcomes. Our data suggest that SEEG may be associated with improvements in working memory and processing speed, representing cognitive domains served by spatially distributed networks. Our study also supports wider use of language ESM before epilepsy surgery, preferably using other language tasks in addition to visual naming. Rather than the type of electrode, postsurgical neuropsychological outcomes are driven by whether language ESM was performed or not, with beneficial effects of language mapping.

Tolerability of transcranial magnetic stimulation language mapping in children.

OBJECTIVE: Transcranial Magnetic Stimulation (TMS) has emerged as a viable non-invasive method for mapping language networks. Little is known about the tolerability of transcranial magnetic stimulation language mapping in children. METHODS: Children aged 5-18 years underwent bilateral language mapping using repetitive transcranial magnetic stimulation (rTMS) to target 33 sites/hemisphere. Stimulation was delivered at 5 Hz, in 1-2 second bursts, during visual naming and auditory verb generation. Pain unpleasantness and pain intensity were assessed using an unpleasantness visual analog scale (VAS). RESULTS: 49 participants tolerated motor mapping and had repetitive transcranial magnetic stimulation. 35/49 (71%) completed visual naming and 26/49 (53%) completed both visual naming and verb generation. Mean electrical field per participant was 115 V/m. Young age and lower language ability were associated with lower completion. Visual analogue scale scores were significantly higher (6.1 vs. 2.8) in participants who withdrew early compared to those who completed at least visual naming. CONCLUSIONS: Pain measured by VAS was a major contributor to early withdrawal. However, a complete bilateral map was obtained with one paradigm in 71% of participants. Future studies designed to reduce pain during repetitive transcranial magnetic stimulation over language cortex will boost viability. SIGNIFICANCE: This study represents the first attempt to characterize tolerability of bilateral repetitive transcranial magnetic stimulation language mapping in healthy children.

The involvement of CdhR in Porphyromonas gingivalis during nitric oxide stress.

Porphyromonas gingivalis, the causative agent of adult periodontitis, must gain resistance to frequent oxidative and nitric oxide (NO) stress attacks from immune cells in the periodontal pocket to survive. Previously, we found that, in the wild-type and under NO stress, the expression of PG1237 (CdhR), the gene encoding for a putative LuxR transcriptional regulator previously called community development and hemin regulator (CdhR), was upregulated 7.7-fold, and its adjacent gene PG1236 11.9-fold. Isogenic mutants P. gingivalis FLL457 (ΔCdhR::ermF), FLL458 (ΔPG1236::ermF), and FLL459 (ΔPG1236-CdhR::ermF) were made by allelic exchange mutagenesis to determine the involvement of these genes in P. gingivalis W83 NO stress resistance. The mutants were black pigmented and ß hemolytic and their gingipain activities varied with strains. FLL457 and FLL459 mutants were more sensitive to NO compared to the wild type, and complementation restored NO sensitivity to that of the wild type. DNA microarray analysis of FLL457 showed that approximately 2% of the genes were upregulated and over 1% of the genes downregulated under NO stress conditions compared to the wild type. Transcriptome analysis of FLL458 and FLL459 under NO stress showed differences in their modulation patterns. Some similarities were also noticed between all mutants. The PG1236-CdhR gene cluster revealed increased expression under NO stress and may be part of the same transcriptional unit. Recombinant CdhR showed binding activity to the predicted promoter regions of PG1459 and PG0495. Taken together, the data indicate that CdhR may play a role in NO stress resistance and be involved in a regulatory network in P. gingivalis.

Automated, machine learning-based alerts increase epilepsy surgery referrals: A randomized controlled trial.

OBJECTIVE: To determine whether automated, electronic alerts increased referrals for epilepsy surgery. METHODS: We conducted a prospective, randomized controlled trial of a natural language processing-based clinical decision support system embedded in the electronic health record (EHR) at 14 pediatric neurology outpatient clinic sites. Children with epilepsy and at least two prior neurology visits were screened by the system prior to their scheduled visit. Patients classified as a potential surgical candidate were randomized 2:1 for their provider to receive an alert or standard of care (no alert). The primary outcome was referral for a neurosurgical evaluation. The likelihood of referral was estimated using a Cox proportional hazards regression model. RESULTS: Between April 2017 and April 2019, at total of 4858 children were screened by the system, and 284 (5.8%) were identified as potential surgical candidates. Two hundred four patients received an alert, and 96 patients received standard care. Median follow-up time was 24 months (range: 12-36 months). Compared to the control group, patients whose provider received an alert were more likely to be referred for a presurgical evaluation (3.1% vs 9.8%; adjusted hazard ratio [HR] = 3.21, 95% confidence interval [CI]: 0.95-10.8; one-sided p = .03). Nine patients (4.4%) in the alert group underwent epilepsy surgery, compared to none (0%) in the control group (one-sided p = .03). SIGNIFICANCE: Machine learning-based automated alerts may improve the utilization of referrals for epilepsy surgery evaluations.

Comparing electrical stimulation functional mapping with subdural electrodes and stereoelectroencephalography.

OBJECTIVE: Electrical stimulation mapping (ESM) is the clinical standard for functional localization with subdural electrodes (SDE). As stereoelectroencephalography (SEEG) has emerged as an alternative option, we compared functional responses, afterdischarges (ADs), and unwanted ESM-induced seizures (EISs) between the two electrode types. METHODS: Incidence and current thresholds for functional responses (sensory, motor, speech/language), ADs, and EISs were compared between SDE and SEEG using mixed models incorporating relevant covariates. RESULTS: We identified 67 SEEG ESM and 106 SDE ESM patients (7207 and 4980 stimulated contacts, respectively). We found similar incidence of language and motor responses between electrode types; however, more SEEG patients reported sensory responses. ADs and EISs occurred less commonly with SEEG than SDE. Current thresholds for language, face motor, and upper extremity (UE) motor responses and EIS significantly decreased with age. However, they were not affected by electrode type, premedication, or dominant hemispheric stimulation. AD thresholds were higher with SEEG than with SDE. For SEEG ESM, language thresholds remained below AD thresholds up to 26 years of age, whereas this relationship was inverse for SDE. Also, face and UE motor thresholds fell below AD thresholds at earlier ages for SEEG than SDE. AD and EIS thresholds were not affected by premedication. SIGNIFICANCE: SEEG and SDE have clinically relevant differences for functional brain mapping with electrical stimulation. Although evaluation of language and motor regions is comparable between SEEG and SDE, SEEG offers a higher likelihood of identifying sensory areas. A lower incidence of ADs and EISs, and a favorable relationship between functional and AD thresholds suggest superior safety and neurophysiologic validity for SEEG ESM than SDE ESM.

Local and Systemic Effects of Porphyromonas gingivalis Infection.

Porphyromonas gingivalis, a gram-negative anaerobe, is a leading etiological agent in periodontitis. This infectious pathogen can induce a dysbiotic, proinflammatory state within the oral cavity by disrupting commensal interactions between the host and oral microbiota. It is advantageous for P. gingivalis to avoid complete host immunosuppression, as inflammation-induced tissue damage provides essential nutrients necessary for robust bacterial proliferation. In this context, P. gingivalis can gain access to the systemic circulation, where it can promote a prothrombotic state. P. gingivalis expresses a number of virulence factors, which aid this pathogen toward infection of a variety of host cells, evasion of detection by the host immune system, subversion of the host immune responses, and activation of several humoral and cellular hemostatic factors.

The Oxidative Stress-Induced Hypothetical Protein PG_0686 in Porphyromonas gingivalis W83 Is a Novel Diguanylate Cyclase.

The survival/adaptation of Porphyromonas gingivalis to the inflammatory environment of the periodontal pocket requires an ability to overcome oxidative stress. Several functional classes of genes, depending on the severity and duration of the exposure, were induced in P. gingivalis under H2O2-induced oxidative stress. The PG_0686 gene was highly upregulated under prolonged oxidative stress. PG_0686, annotated as a hypothetical protein of unknown function, is a 60 kDa protein that carries several domains including hemerythrin, PAS10, and domain of unknown function (DUF)-1858. Although PG_0686 showed some relatedness to several diguanylate cyclases (DGCs), it is missing the classical conserved, active site sequence motif (GGD[/E]EF), commonly observed in other bacteria. PG_0686-related proteins are observed in other anaerobic bacterial species. The isogenic mutant P. gingivalis FLL361 (ΔPG_0686::ermF) showed increased sensitivity to H2O2, and decreased gingipain activity compared to the parental strain. Transcriptome analysis of P. gingivalis FLL361 showed the dysregulation of several gene clusters/operons, known oxidative stress resistance genes, and transcriptional regulators, including PG_2212, CdhR and PG_1181 that were upregulated under normal anaerobic conditions. The intracellular level of c-di-GMP in P. gingivalis FLL361 was significantly decreased compared to the parental strain. The purified recombinant PG_0686 (rPG_0686) protein catalyzed the formation of c-di-GMP from GTP. Collectively, our data suggest a global regulatory property for PG_0686 that may be part of an unconventional second messenger signaling system in P. gingivalis. Moreover, it may coordinately regulate a pathway(s) vital for protection against environmental stress, and is significant in the pathogenicity of P. gingivalis and other anaerobes. IMPORTANCE Porphyromonas gingivalis is an important etiological agent in periodontitis and other systemic diseases. There is still a gap in our understanding of the mechanisms that P. gingivalis uses to survive the inflammatory microenvironment of the periodontal pocket. The hypothetical PG_0686 gene was highly upregulated under prolonged oxidative stress. Although the tertiary structure of PG_0686 showed little relatedness to previously characterized diguanylate cyclases (DGCs), and does not contain the conserved GGD(/E)EF catalytic domain motif sequence, an ability to catalyze the formation of c-di-GMP from GTP is demonstrated. The second messenger pathway for c-di-GMP was previously predicted to be absent in P. gingivalis. PG_0686 paralogs are identified in other anaerobic bacteria. Thus, PG_0686 may represent a novel class of DGCs, which is yet to be characterized. In conclusion, we have shown, for the first time, evidence for the presence of c-di-GMP signaling with environmental stress protective function in P. gingivalis.

Characterization of FA1654: A putative DPS protein in Filifactor alocis.

The survival/adaptation of Filifactor alocis, a fastidious Gram-positive asaccharolytic anaerobe, to the inflammatory environment of the periodontal pocket requires an ability to overcome oxidative stress. Moreover, its pathogenic characteristics are highlighted by its capacity to survive in the oxidative-stress microenvironment of the periodontal pocket and a likely ability to modulate the microbial community dynamics. There is still a significant gap in our understanding of its mechanism of oxidative stress resistance and its impact on the virulence and pathogenicity of the microbial biofilm. Coinfection of epithelial cells with F. alocis and Porphyromonas gingivalis resulted in the upregulation of several genes, including HMPREF0389_01654 (FA1654). Bioinformatics analysis indicates that FA1654 has a "di-iron binding domain" and could function as a DNA starvation and stationary phase protection (DPS) protein. We have further characterized the FA1654 protein to determine its role in oxidative stress resistance in F. alocis. In the presence of hydrogen peroxide-induced oxidative stress, there was an ∼1.3 fold upregulation of the FA1654 gene in F. alocis. Incubation of the purified FA1654 protein with DNA in the presence of hydrogen peroxide and iron resulted in the protection of the DNA from Fenton-mediated degradation. Circular dichroism and differential scanning fluorimetry studies have documented the intrinsic ability of rFA1654 protein to bind iron; however, the rFA1654 protein is missing the intrinsic ability to reduce hydrogen peroxide. Collectively, the data may suggest that FA1654 in F. alocis is involved in oxidative stress resistance via an ability to protect against Fenton-mediated oxidative stress-induced damage.

Posterior Quadrant Disconnection Procedure for Intractable Epilepsy: A Case Series of 5 Young Pediatric Patients.

BACKGROUND: Posterior quadrant disconnection (PQD) has been described as a treatment for patients with refractory posterior quadrant subhemispheric epilepsy. Surgical outcomes are difficult to interpret because of limited literature. OBJECTIVE: To provide insight regarding the operative technique and postsurgical seizure freedom in young pediatric patients who underwent surgical disconnection for the treatment of posterior quadrant subhemispheric epilepsy at our institution. METHODS: The authors retrospectively analyzed a series of 5 patients who underwent PQD between 2019 and 2021. Charts were reviewed for preoperative workup including noninvasive/invasive testing, operative reports, and postoperative follow-up data which included degree of seizure freedom, completion of disconnection, and complications. RESULTS: Five patients were included in this series. The median age at seizure onset was 12 months (range 3-24 months), and the median age at surgery was 36 months (range 22-72 months). Histopathology confirmed focal cortical dysplasia in 3 of 5 patients (2 patients with type IB; 1 with type IIID). The average length of follow-up after surgery was 16.8 months (range 12-24 months). All patients underwent complete disconnection of the posterior quadrant without complications. Four of 5 patients (80%) had Engel score of I, while the remaining patient had an Engel score of IIB. CONCLUSION: Our early results demonstrate that complete PQD can be successful at providing excellent seizure freedom and functional outcomes in carefully selected young pediatric patients who have concordant seizure semiology, noninvasive/invasive testing, and imaging findings with primary seizure onset zone within the ipsilateral posterior quadrant. Meticulous surgical planning and thorough understanding of the surgical anatomy and technique are critical to achieving complete disconnection.

Diurnal rhythms of spontaneous intracranial high-frequency oscillations.

OBJECTIVE: Seizures are known to occur with diurnal and other rhythms. To gain insight into the neurophysiology of periodicity of seizures, we tested the hypothesis that intracranial high-frequency oscillations (HFOs) show diurnal rhythms and sleep-wake cycle variation. We further hypothesized that HFOs have different rhythms within and outside the seizure-onset zone (SOZ). METHODS: In drug-resistant epilepsy patients undergoing stereotactic-EEG (SEEG) monitoring to localize SOZ, we analyzed the number of 50-200 Hz HFOs/channel/minute (HFO density) through a 24-hour period. The distribution of HFO density during the 24-hour period as a function of the clock time was analyzed with cosinor model, and for non-uniformity with the sleep-wake cycle. RESULTS: HFO density showed a significant diurnal rhythm overall and both within and outside SOZ. This diurnal rhythm of HFO density showed significantly lower amplitude and longer acrophase within SOZ compared to outside SOZ. The peaks of difference in HFO density within and outside SOZ preceded the seizures by approximately 4 hours. The difference in HFO density within and outside SOZ also showed a non-uniform distribution as a function of sleep-wake cycle, with peaks at first hour after arousal and ±2 hours around sleep onset. CONCLUSIONS: Our study shows that the diurnal rhythm of intracranial HFOs is more robust outside the SOZ. This suggests cortical tissue within SOZ generates HFOs relatively more uniformly throughout the day with attenuation of expected diurnal rhythm. The difference in HFO density within and outside SOZ also showed non-uniform distribution according to clock times and the sleep-wake cycle, which can be a potential biomarker for preferential times of pathological cortical excitability. A temporal correlation with seizure occurrence further substantiates this hypothesis.