State-dependent effects of neural stimulation on brain function and cognition.

Invasive and non-invasive brain stimulation methods are widely used in neuroscience to establish causal relationships between distinct brain regions and the sensory, cognitive and motor functions they subserve. When combined with concurrent brain imaging, such stimulation methods can reveal patterns of neuronal activity responsible for regulating simple and complex behaviours at the level of local circuits and across widespread networks. Understanding how fluctuations in physiological states and task demands might influence the effects of brain stimulation on neural activity and behaviour is at the heart of how we use these tools to understand cognition. Here we review the concept of such 'state-dependent' changes in brain activity in response to neural stimulation, and consider examples from research on altered states of consciousness (for example, sleep and anaesthesia) and from task-based manipulations of selective attention and working memory. We relate relevant findings from non-invasive methods used in humans to those obtained from direct electrical and optogenetic stimulation of neuronal ensembles in animal models. Given the widespread use of brain stimulation as a research tool in the laboratory and as a means of augmenting or restoring brain function, consideration of the influence of changing physiological and cognitive states is crucial for increasing the reliability of these interventions.

SARS-CoV-2 Infection during Pregnancy in a Rural Midwest All-delivery Cohort and Associated Maternal and Neonatal Outcomes.

OBJECTIVE: This study aimed to estimate the prevalence of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) among pregnant patients at the time of delivery in a rural Midwest tertiary care hospital and to examine demographics, clinical factors, and maternal and neonatal outcomes associated with SARS-CoV-2 infection during pregnancy. STUDY DESIGN: This prospective cohort study included all delivering patients between May 1 and September 22, 2020 at the University of Iowa Hospitals and Clinics. Plasma SARS-CoV-2 antibody testing was performed. SARS-CoV-2 viral reverse-transcription polymerase chain reaction (RT-PCR) results and maternal and neonatal outcomes were collected from the electronic medical record. Data were analyzed using univariate statistical methods with clustering for multiple births. RESULTS: In total, 1,000 patients delivered between May 1 and September 22, 2020. Fifty-eight (5.8%) were SARS-CoV-2 antibody positive. Twenty-three also tested viral positive during pregnancy. Three of 1,000 (0.3%) were viral positive on admission but antibody negative. The median age was 30 years (interquartile range [IQR]: 26-33 years) and body mass index was 31.75 kg/m2 (IQR 27.7-37.5 kg/m2). The cesarean delivery rate was 34.0%. The study population was primarily white (71.6%); however, 41.0% of SARS-CoV-2 infected patients identified as Black, 18.0% as Hispanic/Latino, 3.3% as Native Hawaiian/Pacific Islander, and only 27.9% as White (p < 0.0001). SARS-CoV-2 infection was more likely in patients without private insurance (p = 0.0243). Adverse maternal and/or neonatal outcomes were not more likely in patients with evidence of infection during pregnancy. Two SARS-CoV-2 infected patients were admitted to the intensive care unit. There were no maternal deaths during the study period. CONCLUSION: In this largely rural Midwest population, 6.1% of delivering patients had evidence of past or current SARS-CoV-2 infection. Rates of SARS-CoV-2 during pregnancy were higher among racial and ethnic minorities and patients without private insurance. The SARS-CoV-2 infected patients and their neonates were not found to be at increased risk for adverse outcomes. KEY POINTS: · SARS-CoV-2 seroprevalence rate in pregnant population in Iowa is 5.8%.. · Infections are higher among minorities, non-English speakers, and patients without private insurance.. · No increased adverse maternal/neonatal outcomes observed for SARS-CoV-2 infected mothers..

Social and Financial Outcomes of Living Liver Donation: A Prospective Investigation Within the Adult-to-Adult Living Donor Liver Transplantation Cohort Study 2 (A2ALL-2).

Because results from single-center (mostly kidney) donor studies demonstrate interpersonal relationship and financial strains for some donors, we conducted a liver donor study involving nine centers within the Adult-to-Adult Living Donor Liver Transplantation Cohort Study 2 (A2ALL-2) consortium. Among other initiatives, A2ALL-2 examined the nature of these outcomes following donation. Using validated measures, donors were prospectively surveyed before donation and at 3, 6, 12, and 24 mo after donation. Repeated-measures regression models were used to examine social relationship and financial outcomes over time and to identify relevant predictors. Of 297 eligible donors, 271 (91%) consented and were interviewed at least once. Relationship changes were positive overall across postdonation time points, with nearly one-third reporting improved donor family and spousal or partner relationships and >50% reporting improved recipient relationships. The majority of donors, however, reported cumulative out-of-pocket medical and nonmedical expenses, which were judged burdensome by 44% of donors. Lower income predicted burdensome donation costs. Those who anticipated financial concerns and who held nonprofessional positions before donation were more likely to experience adverse financial outcomes. These data support the need for initiatives to reduce financial burden.

Psychological Outcomes of Living Liver Donors From a Multicenter Prospective Study: Results From the Adult-to-Adult Living Donor Liver Transplantation Cohort Study2 (A2ALL-2).

Although single-center and cross-sectional studies have suggested a modest impact of liver donation on donor psychological well-being, few studies have assessed these outcomes prospectively among a large cohort. We conducted one of the largest, prospective, multicenter studies of psychological outcomes in living liver donors within the Adult-to-Adult Living Donor Liver Transplantation Cohort Study2 (A2ALL-2) consortium. In total, 271 (91%) of 297 eligible donors were interviewed at least once before donation and at 3, 6, 12, and 24 mo after donation using validated measures. We found that living liver donors reported low rates of major depressive (0-3%), alcohol abuse (2-5%), and anxiety syndromes (2-3%) at any given assessment in their first 2 years after donation. Between 4.7% and 9.6% of donors reported impaired mental well-being at various time points. We identified significant predictors for donors' perceptions of being better people and experiencing psychological growth following donation, including age, sex, relationship to recipient, ambivalence and motivation regarding donation, and feeling that donation would make life more worthwhile. Our results highlight the need for close psychosocial monitoring for those donors whose recipients died (n=27); some of those donors experienced guilt and concerns about responsibility. Careful screening and targeted, data-driven follow-up hold promise for optimizing psychological outcomes following this procedure for potentially vulnerable donors.

Prevalence of Lassa virus among rodents trapped in three South-South States of Nigeria.

BACKGROUND & OBJECTIVES: Lassa fever has been endemic in Nigeria since 1969. The rodent Mastomys natalensis has been widely claimed to be the reservoir host of the Lassa virus. This study was designed to investigate the dis- tribution of species of rodents in three states (Edo, Delta and Bayelsa) of Nigeria and to determine the prevalence of Lassa virus amongst trapped rodents in the selected states. METHODS: Rodents were trapped during November 2015 to October 2016 from the three states in South-South re- gion of Nigeria. Total RNA was extracted from the blood collected from the trapped rodents. Reverse transcription polymerase chain reaction (RT-PCR) was used to confirm the presence of Lassa virus in the rodents. RESULTS: The results revealed that six species of rodents were predominantly present in these geographical locations. Mus musculus (39.4%) had the highest prevalence, closely followed by Rattus rattus (36.1%), R. fuscipus (20.3%), M. natalensis (2%), Myosoricinae soricidae (1.2%) and R. norvegicus (1%). The overall positivity (carrier rate) of Lassa virus was 1.6% amongst the 1500 rodents caught in the three states. In Edo and Delta States, the RT-PCR results showed presence of Lassa virus in R. rattus, M. musculus and M. natalensis. On the other hand, only M. na- talensis was detected with the virus, amongst the species of rodents caught in Bayelsa State. M. natalensis recorded the highest Lassa virus among rodents trapped in Edo (87%), Delta (50%) and Bayelsa (11%) States respectively. INTERPRETATION & CONCLUSION: The rather low Lassa virus positive among rodents in Bayelsa State of Nigeria may explain the absence of reports of outbreak of Lassa fever over the past 48 yr in the state. The results also confirmed that apart from Mastomys natalensis, other rodents such as Rattus rattus and Mus musculus may also serve as res- ervoirs for Lassa virus. From the findings of this cross-sectional study, it was concluded that a more comprehensive study on rodents as reservoir host, need to be undertaken across the entire states of Nigeria, for better understanding of the epidemiology and endemicity of Lassa fever.

Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols.

Paired associative stimulation (PAS) induces changes in the excitability of human sensorimotor cortex that outlast the procedure. PAS typically involves repeatedly pairing stimulation of a peripheral nerve that innervates an intrinsic hand muscle with transcranial magnetic stimulation over the representation of that muscle in the primary motor cortex. Depending on the timing of the stimuli (interstimulus interval of 25 or 10 ms), PAS leads to either an increase (PAS25) or a decrease (PAS10) in excitability. Both protocols, however, have been associated with an increase in excitability of nearby muscle representations not specifically targeted by PAS. Based on these spillover effects, we hypothesized that an additive, excitability-enhancing effect of PAS25 applied to one muscle representation may be produced by simultaneously applying PAS25 or PAS10 to a nearby representation. In different experiments prototypical PAS25 targeting the left thumb representation [abductor pollicis brevis (APB)] was combined with either PAS25 or PAS10 applied to the left little finger representation [abductor digiti minimi (ADM)] or, in a control experiment, with PAS10 also targeting the APB. In an additional control experiment PAS10 targeted both representations. The plasticity effects were quantified by measuring the amplitude of motor evoked potentials (MEPs) recorded before and after PAS. As expected, prototypical PAS25 was associated with an increase in MEP amplitude in the APB muscle. This effect was enhanced when PAS also targeted the ADM representation but only when a different interstimulus timing (PAS10) was used. These results suggest that PAS-induced plasticity is modified by concurrently targeting separate motor cortical representations with excitatory and inhibitory protocols.

Prevention Services for Externalizing and Anxiety Symptoms in Low-Income Children: the Role of Parent Preferences in Early Childhood.

Dissemination of prevention programs targeting young children is impeded by challenges with parent engagement. Matching program characteristics to parent preferences is associated with increased retention in clinical/intervention settings, but little is known about the types of prevention programs that interest parents. The objectives of this study were to better understand parents' preferences for services designed to prevent externalizing and anxiety disorders and to identify factors associated with preferences. Ethnically diverse, low-income caregivers (n = 485) of young children (11-60 months) completed surveys on child anxiety and externalizing symptoms, parental worry about their children, parent anxiety symptoms, and preferences for prevention group topics. Parents were more likely to prefer a group targeting externalizing behaviors compared to anxiety. Cluster analysis revealed four groups of children: low symptoms, moderate anxiety-low externalizing, moderate externalizing-low anxiety, and high anxiety and externalizing. Parents' preferences varied according to co-occurrence of child anxiety and externalizing symptoms; interest in a program targeting externalizing problems was associated with elevated externalizing problems (regardless of anxiety symptom level), parent anxiety symptoms, and parent worry about their child. Only parent anxiety symptoms predicted parents' interest in an anxiety-focused program, and preference for an anxiety-focused program was actually reduced if children had co-occurring anxiety and externalizing symptoms versus only anxiety symptoms. Results suggest that parents' interest in a program to prevent externalizing problems was well-aligned with the presenting problem, whereas preferences for anxiety programming suggest a more complex interplay among factors. Parent preferences for targeted programming are discussed within a broader framework of parent engagement.

Targeted prevention of childhood anxiety: engaging parents in an underserved community.

Selective prevention programs hold the promise of alleviating child anxiety symptoms, decreasing the risk for emotional problems across the lifespan. Such programs have particular public health import for young children of poor, underserved communities. Identifying factors related to parent engagement, and methods to improve engagement, are paramount in the effort to develop anxiety-focused, community prevention programs. This feasibility study investigated the effect of an enhanced recruitment strategy to maximize parent engagement, as well as factors related to attendance in a single session focused on anxiety prevention. Participants were poor, ethnic minority parents of children aged 11-71 months (n = 256) who completed a survey that assessed anxiety risk according to trauma exposure, child anxiety, or parent anxiety, as well as preferences for preventive services (phase 1). Those meeting risk criteria (n = 101) were invited to a preventive group session (phase 2). Half of parents received enhanced recruitment (ER), which included personalized outreach, matching parent preferences, and community endorsement. Other parents were invited by mail. Chi square analyses indicated that ER was associated with planning to attend (49 vs. 6% of control). Parents receiving ER were 3.5 times more likely to attend. Higher sociodemographic risk was correlated with higher child anxiety symptoms but not attendance. Results highlight the need for improved strategies for engaging parents in preventive, community-based interventions.

Pathways to service receipt: modeling parent help-seeking for childhood mental health problems.

Understanding parent appraisals of child behavior problems and parental help-seeking can reduce unmet mental health needs. Research has examined individual contributors to help-seeking and service receipt, but use of structural equation modeling (SEM) is rare. SEM was used to examine parents' appraisal of child behavior, thoughts about seeking help, and receipt of professional services in a diverse, urban sample (N = 189) recruited from women infant and children offices. Parents of children 11-60 months completed questionnaires about child behavior and development, parent well-being, help-seeking experiences, and service receipt. Child internalizing, externalizing, and dysregulation problems, language delay, and parent worry about child behavior loaded onto parent appraisal of child behavior. Parent stress and depression were positively associated with parent appraisal (and help-seeking). Parent appraisal and help-seeking were similar across child sex and age. In a final model, parent appraisals were significantly associated with parent thoughts about seeking help, which was significantly associated with service receipt.

The COVID-19 Pandemic, Rising Inflation, and Their Influence on Dining Out Frequency and Spending.

BACKGROUND: High intake of food away from home is associated with poor diet quality. This study examines how the COVID-19 pandemic period and Food Away from Home (FAFH) inflation rate fluctuations influenced dining out behaviors. METHODS: Approximately 2800 individuals in Texas reported household weekly dining out frequency and spending. Responses completed prior to the COVID-19 pandemic (2019 to early 2020) were compared to the post-COVID-19 period (2021 through mid-2022). Multivariate analysis with interaction terms was used to test study hypotheses. RESULTS AND CONCLUSION: From the COVID-19 period (before vs. after), the unadjusted frequency of dining out increased from 3.4 times per week to 3.5 times per week, while the amount spent on dining out increased from $63.90 to $82.20. Once the relationship between dining out (frequency and spending) was adjusted for FAFH interest rate and sociodemographic factors, an increase in dining out frequency post-COVID-19 remained significant. However, the unadjusted increase in dining out spending did not remain significant. Further research to understand the demand for dining out post-pandemic is warranted.

Impact of ablation index settings on pulmonary vein reconnection.

PURPOSE: Ablation index (AI) is a radiofrequency lesion quality marker. The AI value that allows effective and safe pulmonary vein isolation (PVI) is still debated. We evaluated the incidence of acute and late PV reconnection (PVR) with different AI settings and its predictors. METHODS: The Ablation Index Registry is a multicenter study that included patients with paroxysmal/persistent atrial fibrillation (AF) who underwent first-time ablation. Each operator performed the ablation using his preferred ablation catheter (ThermoCool® SmartTouch or Surround Flow) and AI setting (380 posterior-500 anterior and 330 posterior-450 anterior). We divided the study population into two groups according to the AI setting used: group 1 (330-450) and group 2 (380-500). Incidence of acute PVR was validated within 30 min after PVI, whereas the incidence of late PVR was evaluated at repeat procedure. RESULTS: Overall, 490 patients were divided into groups 1 (258) and 2 (232). There was no significant difference in the procedural time, fluoroscopy time, and rate of the first-pass PVI between the two study groups. Acute PVR was observed in 5.6% PVs. The rate of acute PVR was slightly higher in group 2 (64/943, 6.8%, PVs) than in group 1 (48/1045, 4.6% PVs, p = 0.04). Thirty patients (6%) underwent a repeat procedure and late PVR was observed in 57/116 (49%) PVs (number of reconnected PV per patient of 1.9 ± 1.6). A similar rate of late PVR was found in the two study groups. No predictors of acute and late PVR were found. CONCLUSION: Ablation with a lower range of AI is highly effective and is not associated with a higher rate of acute and late PVR. No predictors of PV reconnection were found.

Prevalence of maternal obesity at delivery and association with maternal and neonatal outcomes.

INTRODUCTION: Maternal obesity has been linked to adverse outcomes for mothers and their offspring, including, but not limited to gestational hypertension (gHTN), gestational diabetes (GDM), pre-eclampsia, fetal macrosomia, and emergency cesarean section. Recent investigations have also shown that obesity, as defined by a body mass index (BMI) ≥ 30, especially severe obesity (BMI ≥ 40), is a risk factor for both hospitalization and death from COVID-19. OBJECTIVES: The objective of this study is to determine the prevalence and association of maternal obesity at delivery with adverse antenatal, intrapartum, and neonatal outcomes in a cohort of consecutive delivering patients at a tertiary care center in Iowa from May to September 2020. A secondary objective is to determine if maternal obesity has any relationship to past or current COVID-19 infection status at the time of delivery. This is a secondary analysis of a prospective cohort study to analyze obstetric outcomes among COVID-19 infected and uninfected patients. METHODS: We conducted a prospective cohort study using demographic and clinical data obtained from the electronic medical record. Excess plasma was collected from routine blood samples obtained at delivery admission to determine the seroprevalence of COVID-19 antibody using the DiaSorin and Roche antibody assays. Frequency variables were each calculated separately, and a comparison of maternal and neonatal outcomes was conducted using the generalized linear mixed modeling (GLMM) framework to account for varying distributions (normal and binary). RESULTS: 1001 women delivered during the study period and 89.7% met criteria for being overweight or obese; 17.9% met criteria for severe obesity. Women with obesity had 49.8% lower odds of possessing private insurance, and women with severe obesity were less than half as likely to plan to breastfeed at the time of discharge. Women with obesity of any kind had a significantly increased odds of GDM and gHTN, and an increased risk of an infant with macrosomia, hypoglycemia, and NICU admission. No significant association was found between BMI and COVID-19 infection or disease severity. CONCLUSION: This study provides insight into obstetric complications facing women with obesity, especially those with severe obesity. This report serves to highlight potential challenges, such as insurance status and labor complications, that impact women of high BMI to a greater degree when compared to their normal-weight counterparts.

The obligation to say 'Thank you': heart transplant recipients' experience of writing to the donor family.

Transplant recipients are encouraged to write anonymous thank-you letters to the donor family. We prospectively explored heart transplant recipients' embodied responses to the 'obligation' to write a thank-you letter using audio/video-taped open-ended interviews (N = 27). Fifteen of the 19 participants, who wrote letters to the donor family, expressed or visually revealed significant distress about issues such as the obligation to write anonymously and the inadequacy of the 'thank-you'. Writing the thank-you letter is not a neutral experience for heart transplant recipients. Rethinking the obligatory practice regarding the thank-you letter and developing the necessary support for the recipient through this process is necessary.

Suicide risk in hepatitis C and during interferon-alpha therapy: a review and clinical update.

Chronic hepatitis C (CHC) affects over 170 million individuals worldwide and is a growing public health concern. Despite the availability of CHC treatment, specifically interferon-α and ribavirin, treatment of CHC is limited by concerns about psychiatric side effects including risks of suicide. Although depression has been the focus of neuropsychiatric complications from interferon-alpha (IFNα), emerging evidence has contributed to our understanding of IFNα-induced suicidal ideation and attempts. Using Pubmed, we performed a literature review of all English articles published between 1989 and April 1, 2010 on suicide in untreated and IFNα-treated patients with CHC. References in all identified review articles were scanned and included in our review. A total of 17 articles were identified. Studies have suggested that the first 12 weeks of IFNα therapy are the high-risk period. Moreover, the emergence of suicidal ideation can be linked to neuropsychiatric abnormalities, specifically serotonin depletion. Pretreatment with antidepressant treatment should be reserved for high-risk groups, as this may reduce the risk of depression and thus decrease the suicide risk indirectly. Although there is a paucity of literature on suicide and suicide risk during IFNα therapy for CHC, recent studies on IFNα-induced depression have provided some potential insights into suicide in this patient population. Further research examining the effects of pharmacological and nonpharmacological interventions on suicide risk during IFNα treatment is needed.

Anonymous living liver donation: donor profiles and outcomes.

There are no published series of the assessment process, profiles and outcomes of anonymous, directed or nondirected live liver donation. The outcomes of 29 consecutive potential anonymous liver donors at our center were assessed. We used our standard live liver assessment process, augmented with the following additional acceptance criteria: a logical rationale for donation, a history of social altruism, strong social supports and a willingness to maintain confidentiality of patient information. Seventeen potential donors were rejected and 12 donors were ultimately accepted (six male, six female). All donors were strongly motivated by a desire and sense of responsibility to help others. Four donations were directed toward recipients who undertook media appeals. The donor operations included five left lateral segmentectomies and seven right hepatectomies. The overall donor morbidity was 40% with one patient having a transient Clavien level 3 complication (a pneumothorax). All donors are currently well. None expressed regret about their decision to donate, and all volunteered the opinion that donation had improved their lives. The standard live liver donor assessment process plus our additional requirements appears to provide a robust assessment process for the selection of anonymous live liver donors. Acceptance of anonymous donors enlarges the donor liver pool.

Adult living liver donors have excellent long-term medical outcomes: the University of Toronto liver transplant experience.

Right lobe living donor liver transplantation is an effective treatment for selected individuals with end-stage liver disease. Although 1 year donor morbidity and mortality have been reported, little is known about outcomes beyond 1 year. Our objective was to analyze the outcomes of the first 202 consecutive donors performed at our center with a minimum follow-up of 12 months (range 12-96 months). All physical complications were prospectively recorded and categorized according to the modified Clavien classification system. Donors were seen by a dedicated family physician at 2 weeks, 1, 3 and 12 months postoperatively and yearly thereafter. The cohort included 108 males and 94 females (mean age 37.3 +/- 11.5 years). Donor survival was 100%. A total of 39.6% of donors experienced a medical complication during the first year after surgery (21 Grade 1, 27 Grade 2, 32 Grade 3). After 1 year, three donors experienced a medical complication (1 Grade 1, 1 Grade 2, 1 Grade 3). All donors returned to predonation employment or studies although four donors (2%) experienced a psychiatric complication. This prospective study suggests that living liver donation can be performed safely without any serious late medical complications and suggests that long-term follow-up may contribute to favorable donor outcomes.

Effects of tDCS on visual statistical learning.

Visual statistical learning describes the encoding of structure in sensory input, and it has important consequences for cognition and behaviour. Higher-order brain regions in the prefrontal and posterior parietal cortices have been associated with statistical learning behaviours. Yet causal evidence of a cortical contribution remains limited. In a recent study, the modulation of cortical activity by transcranial direct current stimulation (tDCS) disrupted statistical learning in a spatial contextual cueing phenomenon; supporting a cortical role. Here, we examined whether the same tDCS protocol would influence statistical learning assessed by the Visual Statistical Learning phenomenon (i.e., Fiser and Aslin, 2001), which uses identity-based regularities while controlling for spatial location. In Experiment 1, we employed the popular exposure-test design to tap the learning of structure after passive viewing. Using a large sample (N = 150), we found no effect of the tDCS protocol when compared to a sham control nor to an active control region. In Experiment 2 (N = 80), we developed an online task that was sensitive to the timecourse of learning. Under these task conditions, we did observe a stimulation effect on learning, consistent with the previous work. The way tDCS affected learning appeared to be task-specific; expediting statistical learning in this case. Together with the existing evidence, these findings support the hypothesis that cortical areas are involved in the visual statistical learning process, and suggest the mechanisms of cortical involvement may be task-dependent and dynamic across time.

Adult right-lobe living liver donors: quality of life, attitudes and predictors of donor outcomes.

To refine selection criteria for adult living liver donors and improve donor quality of care, risk factors for poor postdonation health-related quality of life (HRQOL) must be identified. This cross-sectional study examined donors who underwent a right hepatectomy at the University of Toronto between 2000 and 2007 (n = 143), and investigated predictors of (1) physical and mental health postdonation, as well as (2) willingness to participate in the donor process again. Participants completed a standardized HRQOL measure (SF-36) and measures of the pre- and postdonation process. Donor scores on the SF-36 physical and mental health indices were equivalent to, or greater than, population norms. Greater predonation concerns, a psychiatric diagnosis and a graduate degree were associated with lower mental health postdonation whereas older donors reported better mental health. The majority of donors (80%) stated they would donate again but those who perceived that their recipient engaged in risky health behaviors were more hesitant. Prospective donors with risk factors for lower postdonation satisfaction and mental health may require more extensive predonation counseling and postdonation psychosocial follow-up. Risk factors identified in this study should be prospectively evaluated in future research.

Chemical composition of lunar material.

Chemical and emission spectrographic analyses of three Apollo 11 samples, 10017-29, 10020-30, and 10084-132, are given. Major and minor constituents were determined both by conventional rock analysis methods and by a new composite scheme utilizing a lithium fluoborate method for dissolution of the samples and atomic absorption spectroscopy and colorimetry. Trace constituents were determined by optical emission spectroscopy involving a d-c arc, air-jet controlled.

The Human Odontoblast Cell Layer and Dental Pulp Proteomes and N-Terminomes.

The proteome and N-terminome of the human odontoblast cell layer were identified for the first time by shotgun proteomic and terminal amine isotopic labeling of substrates (TAILS) N-terminomic analyses, respectively, and compared with that of human dental pulp stroma from 26 third molar teeth. After reverse-phase liquid chromatography-tandem mass spectrometry, >170,000 spectra from the shotgun and TAILS analyses were matched by 4 search engines to 4,888 and 12,063 peptides in the odontoblast cell layer and pulp stroma, respectively. Within these peptide groups, 1,543 and 5,841 protein N-termini, as well as 895 and 2,423 unique proteins, were identified with a false discovery rate of ≤1%. Thus, the human dental pulp proteome was expanded by 974 proteins not previously identified among the 4,123 proteins in our 2015 dental pulp study. Further, 222 proteins of the odontoblast cell layer were not found in the pulp stroma, suggesting many of these proteins are synthesized only by odontoblasts. When comparing the proteomes of older and younger donors, differences were more apparent in the odontoblast cell layer than in the dental pulp stroma. In the odontoblast cell layer proteome, we found proteomic evidence for dentin sialophosphoprotein, which is cleaved into dentin sialoprotein and dentin phosphoprotein. By exploring the proteome of the odontoblast cell layer and expanding the known dental pulp proteome, we found distinct proteome differences compared with each other and with dentin. Moreover, between 61% and 66% of proteins also occurred as proteoforms commencing with a neo-N-terminus not annotated in UniProt. Hence, TAILS increased proteome coverage and revealed considerable proteolytic processing, by identifying stable proteoforms in these dynamic dental tissues. All mass spectrometry raw data have been deposited to ProteomeXchange with the identifier , with the accompanying metadata at Mendeley Data ( https://data.mendeley.com/datasets/b57zfh6wmy/1 ).