Change in neurocognitive functioning in patients with treatment-resistant depression with serial intravenous ketamine infusions: The Bio-K multicenter trial

This nonrandomized, multicenter, open-label clinical trial explored the impact of intravenous (IV) ketamine on cognitive function in adults (n = 74) with treatment-resistant depression (TRD). Patients received three IV ketamine infusions during the acute phase and, if remitted, four additional infusions in the continuation phase (Mayo site). Cognitive assessments using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) were conducted at baseline, end of the acute phase, and end of the continuation phase (Mayo site). Results showed a significant 53 % (39/74) remission rate in depression symptoms after the acute phase. In adjusted models, baseline language domain score was associated with a higher odd of remission (Odds Ratio, 1.09, 95 % CI = 1.03-1.17, p = 0.004) and greater improvement in MADRS at the end of the acute phase (β =-0.97; 95 % CI, -1.74 to -0.20; P = 0.02). The likelihood of remission was not significantly associated with baseline immediate or delayed memory, visuospatial/constructional, or attention scores. In the continuation phase, improvements in immediate and delayed memory and attention persisted, with additional gains in visuospatial and language domains. Limitations included an open-label design, potential practice effects, and ongoing psychotropic medication use. Overall, the study suggests cognitive improvement, not deterioration, associated with serial IV ketamine administrations for TRD. These findings encourage future studies with larger sample sizes and longer follow-up periods to examine any potential for deleterious effect with recurrent ketamine use for TRD. Trial Registration: ClinicalTrials.gov: NCT03156504.

Clinical outcomes in the biomarkers of ketamine (Bio-K) study of open-label IV ketamine for refractory depression

OBJECTIVE

We conducted an open-label clinical trial ("Bio-K") using IV ketamine for treatment-resistant depression to identify biomarkers linked to remission. Here, we report the clinical efficacy and side effect outcomes of Bio-K.

METHODS

Across 4 US sites, 75 patients ages 18-65 with treatment-refractory unipolar or bipolar depression received 3 IV ketamine infusions over an 11-day period. Key exclusion criteria were psychotic symptoms, significant substance abuse, unstable medical conditions, and any use of cannabis. Pre-existing antidepressant medication was maintained. Primary outcome was remission as measured by Montgomery-Asberg Depression Rating Scale (MADRS), with secondary outcome of 50 % reduction in Beck Suicide Scale score. Safety monitoring and varying durations of infusions were also key parameters.

RESULTS

Using remission as MADRS score <10, after 3 infusions 52 % achieved remission, with 67 % achieving response. Of those achieving response after a single infusion, 66 % (22 of 33) reached remission after 3 infusions, while 40 % (16 of 40) non-responders after the first infusion went on to achieve remission after 3 infusions. Only 20 % of non-responders after 2 infusions achieved remission. Most (81 %) participants had significant suicidal ideation at baseline; of these, two-thirds (67 %) experienced at least a 50 % reduction in suicidality. Side effects were minimal. Uniquely, we had three different types of infusion categories, with individuals receiving: (1) slow (100-min) infusions only or (2) regular (40-min) infusions only or (3) a mix of infusion durations. These three infusion groups showed comparable safety and efficacy. Exploration of clinical factors revealed no link between BMI, age, or gender to remission.

CONCLUSIONS

The consistency of outcomes across 4 clinical sites and across multiple instruments, suggests high acute efficacy and safety of IV ketamine for serious depressive episodes. Duration of infusion did not alter outcomes. Meaningfully, 40 % of non-responders after a single infusion did reach remission subsequently, while only 20 % of non-responders after 2 infusions achieved remission, suggesting early response is suggestive for eventual remission. Our data on varying ketamine infusion duration adds novel insights into the clinical administration of this new treatment for refractory and severe patients. Our limitations included a lack of a control group, necessitating caution about conclusions of efficacy, balanced by the utility of reporting "real-world" outcomes across multiple clinical sites. We could also not separately analyze results for bipolar disorder due to small numbers. Together, the Bio-K clinical results are promising and provide significant sample sizes for forthcoming biological markers analyses.

Trauma and comorbid post-traumatic stress disorder in people with bipolar disorder participating in the Heinz C. Prechter Longitudinal Study

BACKGROUND

It is estimated that up to 50 % of people with bipolar disorder (BD) also have comorbid post-traumatic stress disorder (PTSD). However, little is known about the presentation and treatment of people with this comorbidity.

METHODS

Data from 577 individuals diagnosed with bipolar disorder participating in the Heinz C. Prechter Longitudinal Study of BD were explored at baseline, year two and four. Three trauma groups were created: (i) one trauma (n = 75), (ii) multiple traumas (n = 417), and comorbid PTSD (n = 85). Measures of depression, mania, sleep, number of hospitalisations, suicide attempts, and medication use were analysed using regression modelling to determine differences between the three trauma groups.

RESULTS

There was an increase in depression, mania, and sleep scores and a higher number of hospitalisations in participants with comorbid PTSD compared to those experiencing one trauma. Additionally, increased mania and depression scores were reported in participants experiencing multiple traumas compared to those with one trauma. There was no difference in medication use between those who experienced one trauma compared to those with comorbid PTSD.

LIMITATIONS

The trauma groups may include confounding with more participants experiencing PTSD than reported in this study due to screening processes. Additionally, the severity of trauma was not recorded, therefore number of traumas was utilised as a proxy.

CONCLUSION

Comorbid BD and PTSD is associated with worse symptom scores compared to participants reporting one trauma. Clinical implications include the addition of trauma-informed care to clinical settings to identify PTSD to provide appropriate treatments.

Patterns of pharmacotherapy for bipolar disorder: A GBC survey

OBJECTIVES

To understand treatment practices for bipolar disorders (BD), this study leveraged the Global Bipolar Cohort collaborative network to investigate pharmacotherapeutic treatment patterns in multiple cohorts of well-characterized individuals with BD in North America, Europe, and Australia.

METHODS

Data on pharmacotherapy, demographics, diagnostic subtypes, and comorbidities were provided from each participating cohort. Individual site and regional pooled proportional meta-analyses with generalized linear mixed methods were conducted to identify prescription patterns.

RESULTS

This study included 10,351 individuals from North America (n = 3985), Europe (n = 3822), and Australia (n = 2544). Overall, participants were predominantly female (60%) with BD-I (60%; vs. BD-II = 33%). Cross-sectionally, mood-stabilizing anticonvulsants (44%), second-generation antipsychotics (42%), and antidepressants (38%) were the most prescribed medications. Lithium was prescribed in 29% of patients, primarily in the Australian (31%) and European (36%) cohorts. First-generation antipsychotics were prescribed in 24% of the European versus 1% in the North American cohort. Antidepressant prescription rates were higher in BD-II (47%) compared to BD-I (35%). Major limitations were significant differences among cohorts based on inclusion/exclusion criteria, data source, and time/year of enrollment into cohort.

CONCLUSIONS

Mood-stabilizing anticonvulsants, second-generation antipsychotics, and antidepressants were the most prescribed medications suggesting prescription patterns that are not necessarily guideline concordant. Significant differences exist in the prescription practices across different geographic regions, especially the underutilization of lithium in the North American cohorts and the higher utilization of first-generation antipsychotics in the European cohorts. There is a need to conduct future longitudinal studies to further explore these differences and their impact on outcomes, and to inform and implement evidence-based guidelines to help improve treatment practices in BD.

The Human Phenotype Ontology in 2024: phenotypes around the world

The Human Phenotype Ontology (HPO) is a widely used resource that comprehensively organizes and defines the phenotypic features of human disease, enabling computational inference and supporting genomic and phenotypic analyses through semantic similarity and machine learning algorithms. The HPO has widespread applications in clinical diagnostics and translational research, including genomic diagnostics, gene-disease discovery, and cohort analytics. In recent years, groups around the world have developed translations of the HPO from English to other languages, and the HPO browser has been internationalized, allowing users to view HPO term labels and in many cases synonyms and definitions in ten languages in addition to English. Since our last report, a total of 2239 new HPO terms and 49235 new HPO annotations were developed, many in collaboration with external groups in the fields of psychiatry, arthrogryposis, immunology and cardiology. The Medical Action Ontology (MAxO) is a new effort to model treatments and other measures taken for clinical management. Finally, the HPO consortium is contributing to efforts to integrate the HPO and the GA4GH Phenopacket Schema into electronic health records (EHRs) with the goal of more standardized and computable integration of rare disease data in EHRs.

Comparative mortality risks in two independent bipolar cohorts

OBJECTIVES

To compare mortality rates in bipolar disorder with common causes of mortality.

METHODS

Observational data from the Prechter Longitudinal Study of Bipolar Disorder (PLS-BD) of 1128 participants including 281 controls was analyzed using logistical regression to quantify mortality rates in comparison with common comorbidities and causes of death. Outcome and treatment measures, including ASRM, GAD-7, PHQ-9 and medication use were used to stratify those with bipolar disorder (BD) that are alive or deceased. A larger cohort of 10,735 existing BD patients with 7,826 controls (no psychiatric diagnosis) from the University of Michigan Health (U-M Health) clinics was used as replication, observational secondary data analysis.

RESULTS

The mortality rates are significantly different between those with BD and controls in both PLS-BD and U-M Health. Those with BD and are deceased have a higher percentage of elevated depression measures but show no difference in mania or anxiety measures nor medication use patterns. In both cohorts, a diagnosis of BD increases the odds of mortality greater than history of smoking or being older than ≥ 60-years of age.

CONCLUSION

BD was found to increase odds of mortality significantly and beyond that of a history of smoking. This finding was replicated in an independent sample.

Circadian rhythm disruptions associated with opioid use disorder in synaptic proteomes of human dorsolateral prefrontal cortex and nucleus accumbens

Opioid craving and relapse vulnerability is associated with severe and persistent sleep and circadian rhythm disruptions. Understanding the neurobiological underpinnings of circadian rhythms and opioid use disorder (OUD) may prove valuable for developing new treatments for opioid addiction. Previous work indicated molecular rhythm disruptions in the human brain associated with OUD, highlighting synaptic alterations in the dorsolateral prefrontal cortex (DLPFC) and nucleus accumbens (NAc)-key brain regions involved in cognition and reward, and heavily implicated in the pathophysiology of OUD. To provide further insights into the synaptic alterations in OUD, we used mass-spectrometry based proteomics to deeply profile protein expression alterations in bulk tissue and synaptosome preparations from DLPFC and NAc of unaffected and OUD subjects. We identified 55 differentially expressed (DE) proteins in DLPFC homogenates, and 44 DE proteins in NAc homogenates, between unaffected and OUD subjects. In synaptosomes, we identified 161 and 56 DE proteins in DLPFC and NAc, respectively, of OUD subjects. By comparing homogenate and synaptosome protein expression, we identified proteins enriched specifically in synapses that were significantly altered in both DLPFC and NAc of OUD subjects. Across brain regions, synaptic protein alterations in OUD subjects were primarily identified in glutamate, GABA, and circadian rhythm signaling. Using time-of-death (TOD) analyses, where the TOD of each subject is used as a time-point across a 24-h cycle, we were able to map circadian-related changes associated with OUD in synaptic proteomes associated with vesicle-mediated transport and membrane trafficking in the NAc and platelet-derived growth factor receptor beta signaling in DLPFC. Collectively, our findings lend further support for molecular rhythm disruptions in synaptic signaling in the human brain as a key factor in opioid addiction.

Circadian rhythm disruptions associated with opioid use disorder in the synaptic proteomes of the human dorsolateral prefrontal cortex and nucleus accumbens

Opioid craving and relapse vulnerability is associated with severe and persistent sleep and circadian rhythm disruptions. Understanding the neurobiological underpinnings of circadian rhythms and opioid use disorder (OUD) may prove valuable for developing new treatments for opioid addiction. Previous work indicated molecular rhythm disruptions in the human brain associated with OUD, highlighting synaptic alterations in the dorsolateral prefrontal cortex (DLPFC) and nucleus accumbens (NAc)-key brain regions involved in cognition and reward, and heavily implicated in the pathophysiology of OUD. To provide further insights into the synaptic alterations in OUD, we used mass-spectrometry based proteomics to deeply profile protein expression alterations in bulk tissue and synaptosome preparations from DLPFC and NAc of unaffected and OUD subjects. We identified 55 differentially expressed (DE) proteins in DLPFC homogenates, and 44 DE proteins in NAc homogenates, between unaffected and OUD subjects. In synaptosomes, we identified 161 and 56 DE proteins in DLPFC and NAc, respectively, of OUD subjects. By comparing homogenate and synaptosome protein expression, we identified proteins enriched specifically in synapses that were significantly altered in both DLPFC and NAc of OUD subjects. Across brain regions, synaptic protein alterations in OUD subjects were primarily identified in glutamate, GABA, and circadian rhythm signaling. Using time-of-death (TOD) analyses, where the TOD of each subject is used as a time-point across a 24- hour cycle, we were able to map circadian-related changes associated with OUD in synaptic proteomes related to vesicle-mediated transport and membrane trafficking in the NAc and platelet derived growth factor receptor beta signaling in DLPFC. Collectively, our findings lend further support for molecular rhythm disruptions in synaptic signaling in the human brain as a key factor in opioid addiction.

Childhood trauma relates to worse memory functioning in bipolar disorder

BACKGROUND

Childhood trauma is commonly experienced by individuals diagnosed with bipolar disorder (BP). In BP, childhood trauma is related to a more severe clinical course, but its association with cognition remains unclear.

METHODS

This study evaluated 405 adult participants diagnosed with BP and 136 controls. Participants completed the Childhood Trauma Questionnaire and a comprehensive neuropsychological battery. High versus low childhood trauma was defined with one standard deviation above the control participant's mean Childhood Trauma Questionnaire score. Neuropsychological data was transformed into eight cognitive factors, including four executive functioning, auditory and visual memory, fine motor, and emotion processing. Multivariate analysis of covariance evaluated group differences in cognition, while adjusting for covariates.

RESULTS

There were significant differences among the three groups, F(16, 968) = 4.05, p < .001, Wilks' Λ = 0.88, partial η² = 0.06. Comparing the high and low trauma BP groups, high trauma was related to lower auditory and visual memory factor scores (p < .05). As compared to controls, the BP high trauma group had lower scores on six of eight factors (all p < .01), while the BP low trauma group had lower scores on four of eight factors (all p < .01).

LIMITATIONS

Analyses of factor score do not address which aspect of the memory process is affected and biomarkers may help guide interventions addressing underlying biological process.

CONCLUSIONS

Adults diagnosed with BP with higher childhood trauma have worse memory functioning, beyond the lower childhood trauma BP group, highlighting the importance of understanding the long-term cognitive outcomes of childhood trauma.

Interpersonal Trauma and Depression Severity Among Individuals With Bipolar Disorder: Findings From the Prechter Longitudinal Study of Bipolar Disorder

Background: Experiences of interpersonal trauma, both in childhood and in adulthood, can affect the trajectory of bipolar disorder (BD). However, the degree to which childhood and/or adult trauma impacts the longitudinal trajectory of depression severity among individuals with BD actively receiving treatment remains unclear.

Methods: The effects of childhood trauma (Childhood Trauma Questionnaire) and adult trauma (Life Events Checklist) on depression severity (Hamilton Depression Rating Scale) were investigated in a treatment-receiving subsample with BD (DSM-IV) of the Prechter Longitudinal Study of Bipolar Disorder (2005-present). A mixed-effects linear regression model was used to assess the trajectory of depression severity over 4 years.

Results: Depression severity was evaluated in 360 participants, of whom 267 (74.8%) reported a history of interpersonal trauma. A history of childhood trauma alone (n = 110) and childhood and adult trauma combined (n = 108)-but not adult trauma alone (n = 49) -were associated with greater depression severity at the 2-year and 6-year follow-up assessments. However, the trajectory of depression severity (ie, change over time) was similar between participants with a history of childhood trauma, those with a history of adult trauma, and those with no history of interpersonal trauma. Interestingly, participants with a history of both types of trauma showed more improvement in depression severity (ie, from year 2 to year 4: β = 1.67, P = .019).

Conclusions: Despite actively receiving treatment for BD, participants with a history of interpersonal trauma-particularly childhood trauma-presented with more severe depressive symptoms at several follow-up assessments. Hence, interpersonal trauma may represent an essential treatment target.

Heightened inflammation in bipolar disorder occurs independent of symptom severity and is explained by body mass index

Inflammation is hypothesized to be a key component of bipolar disorder (BP) development and progression. However, findings linking BP prevalence and symptomology to immune functioning have been mixed, with some work suggesting that obesity may play an important role in BP-relevant inflammation. Here we investigate differences in biomarkers of inflammation [C-reactive protein (CRP), interleukin (IL)-1β, IL-6, IL-8, IL-10] between healthy controls (HC) and individuals with BP or other mental illness (MI). Adults with BP, MI, or HC (n = 545, 70% BP, 21% HC, 9% MI) self-reported depressive and manic symptoms close to a blood draw and physical exam that included measurement of height and weight. A composite score was calculated from the four cytokines measured in plasma; follow-up analyses explored a pro-inflammatory composite and IL-10, individually. BP individuals had elevated cytokine concentrations compared to HC (B = 0.197, [0.062, 0.333], t (542) = 2.855, p = .004); this difference was also evident for the pro-inflammatory composite and for IL-10. Cytokine concentrations were not associated with BP mood states. Body mass index (BMI), an indicator of obesity, was significantly higher in BP compared to HC (B = 3.780, [2.118, 5.443], t (479) = 4.457, p < .001) and differences in cytokines between the two groups was no longer significant after controlling for BMI. No differences in CRP were evident between BP and HC. These results suggest that cytokine concentrations are elevated in BP and this difference from HC is associated with obesity. Interventions targeting immune modulators in BP must carefully consider the complex relationships within the BP-inflammation-obesity triangle.

Childhood trauma and depressive symptoms in bipolar disorder: A network analysis

BACKGROUND

Childhood trauma is related to an increased number of depressive episodes and more severe depressive symptoms in bipolar disorder. The evaluation of the networks of depressive symptoms-or the patterns of relationships between individual symptoms-among people with bipolar disorder with and without a history of childhood trauma may assist in further clarifying this complex relationship.

METHODS

Data from over 500 participants from the Heinz C. Prechter Longitudinal Study of Bipolar Disorder were used to construct a series of regularised Gaussian Graphical Models. The networks of individual depressive symptoms-self-reported (Patient Health Questionnaire-9; n = 543) and clinician-rated (Hamilton Depression Rating Scale-17; n = 529)-among participants with bipolar disorder with and without a history of childhood trauma (Childhood Trauma Questionnaire) were characterised and compared.

RESULTS

Across the sets of networks, depressed mood consistently emerged as a central symptom (as indicated by strength centrality and expected influence); regardless of participants' history of childhood trauma. Additionally, feelings of worthlessness emerged as a key symptom in the network of self-reported depressive symptoms among participants with-but not without-a history of childhood trauma.

CONCLUSION

The present analyses-although exploratory-provide nuanced insights into the impact of childhood trauma on the presentation of depressive symptoms in bipolar disorder, which have the potential to aid detection and inform targeted intervention development.

Predictors of functional impairment in bipolar disorder: Results from 13 cohorts from seven countries by the global bipolar cohort collaborative

OBJECTIVES

Persistent functional impairment is common in bipolar disorder (BD) and is influenced by a number of demographic, clinical, and cognitive features. The goal of this project was to estimate and compare the influence of key factors on community function in multiple cohorts of well-characterized samples of individuals with BD.

METHODS

Thirteen cohorts from 7 countries included n = 5882 individuals with BD across multiple sites. The statistical approach consisted of a systematic uniform application of analyses across sites. Each site performed a logistic regression analysis with empirically derived "higher versus lower function" as the dependent variable and selected clinical and demographic variables as predictors.

RESULTS

We found high rates of functional impairment, ranging from 41 to 75%. Lower community functioning was associated with depressive symptoms in 10 of 12 of the cohorts that included this variable in the analysis. Lower levels of education, a greater number of prior mood episodes, the presence of a comorbid substance use disorder, and a greater total number of psychotropic medications were also associated with low functioning.

CONCLUSIONS

The bipolar clinical research community is poised to work together to characterize the multi-dimensional contributors to impairment and address the barriers that impede patients' complete recovery. We must also identify the core features which enable many to thrive and live successfully with BD. A large-scale, worldwide, prospective longitudinal study focused squarely on BD and its heterogeneous presentations will serve as a platform for discovery and promote major advances toward optimizing outcomes for every individual with this illness.

Personality traits as mediators of the relationship between childhood trauma and depression severity in bipolar disorder: A structural equation model

BACKGROUND

Childhood trauma is negatively associated with depression severity in bipolar disorder; however, the underlying mechanisms remain unclear. We investigated whether personality traits (neuroticism, extraversion, openness, agreeableness, conscientiousness) mediate the relationship between childhood trauma and the severity of bipolar depression.

METHODS

Data from 209 individuals with bipolar disorder recruited for the Prechter Longitudinal Study of Bipolar Disorder were analysed. Using structural equation modelling, we examined the direct and indirect associations between childhood trauma (Childhood Trauma Questionnaire) and depression severity (Hamilton Depression Rating Scale) - with the personality traits (NEO Personality Inventory-Revised) as mediators.

RESULTS

The direct effect of childhood trauma on depression severity (standardised β = 0.32, 95% bootstrap confidence interval [CI] = 0.20-0.45, p < 0.001) and the indirect effect via neuroticism (standardised β = 0.03, 95% bootstrap CI [0.002, 0.07], p = 0.039) were significant; supporting a partial mediation model. The indirect effect accounted for 9% of the total effect of childhood trauma on depression severity (standardised β = 0.09, 95% bootstrap CI [0.002, 0.19], p = 0.046). The final model had a good fit with the data (comparative fit index = 0.96; root mean square error of approximation = 0.05, 90% CI = [0.02, 0.07]).

CONCLUSION

Personality traits may be relevant psychological mediators that link childhood trauma to a more severe clinical presentation of bipolar depression. Consequently, a person's personality structure may be a crucial operative factor to incorporate in therapeutic plans when treating individuals with bipolar disorder who report a history of childhood trauma.

Attachment insecurity partially mediates the relationship between childhood trauma and depression severity in bipolar disorder

BACKGROUND

Childhood trauma is associated with greater depression severity among individuals with bipolar disorder. However, the mechanisms that explain the link between childhood trauma and depression severity in bipolar disorder remain poorly understood. The mediational role of attachment insecurity in childhood and adulthood was assessed in the current study.

METHODS

Participants with bipolar disorder (N = 143) completed measures of childhood trauma (Childhood Trauma Questionnaire), attachment insecurity (Experiences in Close Relationships Scale) and depression severity (Hamilton Depression Rating Scale) as part of the Prechter Longitudinal Study of Bipolar Disorder. A sequential mediation model was tested using path analysis: the direct and indirect effects of childhood trauma on depression severity with attachment insecurity (attachment anxiety and avoidance) in childhood (mother and father) and adulthood (partner) as mediators were estimated.

RESULTS

The final path model demonstrated an excellent fit to the data (comparative fit index = 0.996; root mean square error of approximation = 0.021 [90% confidence interval = 0.000-0.073]). Supporting the hypothesised sequential mediation model, maternal attachment anxiety in childhood and romantic attachment avoidance in adulthood partially mediated the relationship between childhood trauma and depression severity; this effect accounted for 12% of the total effect of childhood trauma on depression severity.

CONCLUSION

Attachment insecurity in childhood and adulthood form part of the complex mechanism informing why people with bipolar disorder who have a history of childhood trauma experience greater depression severity. Addressing attachment insecurity represents a valuable psychotherapeutic treatment target for bipolar disorder.

Lithium use associated with symptom severity in comorbid bipolar disorder I and migraine

INTRODUCTION

Bipolar disorder (BD) and migraine headaches are frequently comorbid. The common etiological features are unknown, however cortical hyperexcitability (EEG) of migraines, and the report of hyperexcitability in pluripotent stem cell-derived neurons from lithium responsive BD subjects offers a physiological hypothesis of excitable neurons linking these disorders. However, clinical studies suggest that a history of migraine is associated with higher rates of relapse in those with BD taking lithium. Lithium use and history of migraine in this prospective longitudinal study of BD find that lithium use is associated with a greater symptom severity in BD.

METHODS

Data on longitudinal outcome from 538 patients with BD I were categorized according to treatment with lithium and comorbidity with migraine. Clinical outcome measures on depression, mania, and quality of life over the most recent 2-year period compared the BD and BD/migraine cohort according to lithium treatment status.

RESULTS

A history of migraines was associated with worse clinical outcomes of depression (p = .002), mania (p = .005), and mental and physical quality of life (p = .004 and p = .005, respectively), independent of lithium use. The BD/migraine cohort treated with lithium was associated with worse symptoms of mania, whereas those without migraine and lithium use were associated with milder manic symptoms (p = .026).

CONCLUSIONS

Herein, we replicate the relatively worse outcome in BD with comorbid migraine. We find evidence to suggest that lithium use is associated with more severe symptoms of mania among those with BD and a history of migraine and conclude that lithium is contraindicated in BD comorbid with migraine.

The Life Goals Self-Management Mobile App for Bipolar Disorder: Consumer Feasibility, Usability, and Acceptability Study

Background

Life Goals is an evidence-based self-management intervention that assists individuals with bipolar disorder (BD) by aligning BD symptom coping strategies with their personal goals. The intervention can be availed via in-person and telephonic sessions, and it has been recently developed as an individualized, customizable mobile app.

Objective

We examined the feasibility, usability, and acceptability of the Life Goals self-management app among individuals diagnosed with BD who used the app for up to 6 months.

Methods

A total of 28 individuals with BD used the Life Goals app on their personal smartphone for 6 months. They completed key clinical outcome measurements of functioning, disability, and psychiatric symptoms at baseline, 3 months, and 6 months, in addition to a poststudy survey about usability and satisfaction.

Results

Participants used the app for a median of 25 times (IQR 13-65.75), and for a longer time during the first 3 months of the study. The modules on depression and anxiety were the most frequently used, accounting for 35% and 22% of total usage, respectively. Overall, the study participants found the app useful (15/25, 60%) and easy to use (18/25, 72%), and they reported that the screen displayed the material adequately (22/25, 88%). However, less than half of the participants found the app helpful in managing their health (10/25, 40%) or in making progress on their wellness goals (9/25, 36%). Clinical outcomes showed a trend for improvements in mental and physical health and mania-related well-being.

Conclusions

The Life Goals app showed feasibility of use among individuals with BD. Higher user engagement was observed in the initial 3 months with users interested more frequently in the mood modules than other wellness modules. Participants reported acceptability with the ease of app use and satisfaction with the app user interface, but the app showed low success in encouraging self-management within this small sample. The Life Goals app is a mobile health technology that can provide individuals with serious mental illness with more flexible access to evidence-based treatments.

Late chronotype predicts more depressive symptoms in bipolar disorder over a 5 year follow-up period

BACKGROUND

There is increasing evidence that bipolar disorder is influenced by circadian timing, including the timing of sleep and waking activities. Previous studies in bipolar disorder have shown that people with later timed daily activities, also known as late chronotypes, are at higher risk for subsequent mood episodes over the following 12-18 months. However, these studies were limited to euthymic patients and smaller sample sizes. The aim of the current study was to further examine baseline chronotype as a potentially important predictor of mood-related outcomes in a larger sample of individuals with bipolar disorder and over the longest follow up period to date, of 5 years. Participants included 318 adults diagnosed with bipolar I and II (19-86 years) who were enrolled in the Prechter Longitudinal Study of Bipolar Disorder.

RESULTS

Participants with a late chronotype were found to be more likely to have mild to more severe depressive symptoms (PHQ-9 ≥ 5) as captured with PHQ-9 assessments every 2 months over the 5 year follow up period. This higher risk for depressive symptoms remained even after adjusting for age, sex and mood at baseline. Additionally, late chronotypes reported fewer hypomania/mania episodes during the 5 year follow up, as derived from clinical interviews every two years.

CONCLUSIONS

These results highlight the potential clinical usefulness of a single self-report question, in identifying patients at risk for a more depressive mood course. The results also suggest that circadian phase advancing treatments, that can shift circadian timing earlier, should be explored as a means to reduce depressive symptoms in late chronotypes with bipolar disorder.

Dynamics of data-driven microstates in bipolar disorder

Many of the existing models of mood in bipolar disorder can largely be divided into two camps, tracking mood as either a discrete or continuous variable. Both groups rely upon certain assumptions, with most considering only aggregate scores on clinical instruments. In this study, we propose a novel framework that combines elements from both discrete and continuous mood models, using a machine learning pipeline to detect subtle patterns across individuals. Latent factors are constructed from assessments at the item level, then clustered into groups referred to as microstates. Transitions between microstates are captured via a discrete-time Markov chain, allowing for characterization of mood's dynamic nature. Key findings include a factor mapping heavily onto irritability and aggression, as well as a hierarchical pattern of microstates within depression and mania. Validity of these results is confirmed by reproduction in an unseen data set from a separate subject cohort.

Induction of the Immunoproteasome Subunit Lmp7 Links Proteostasis and Immunity in α-Synuclein Aggregation Disorders

Accumulation of aggregated α-synuclein into Lewy bodies is thought to contribute to the onset and progression of dopaminergic neuron degeneration in Parkinson's disease (PD) and related disorders. Although protein aggregation is associated with perturbation of proteostasis, how α-synuclein aggregation affects the brain proteome and signaling remains uncertain. In a mouse model of α-synuclein aggregation, 6% of 6215 proteins and 1.6% of 8183 phosphopeptides changed in abundance, indicating conservation of proteostasis and phosphorylation signaling. The proteomic analysis confirmed changes in abundance of proteins that regulate dopamine synthesis and transport, synaptic activity and integrity, and unearthed changes in mRNA binding, processing and protein translation. Phosphorylation signaling changes centered on axonal and synaptic cytoskeletal organization and structural integrity. Proteostatic responses included a significant increase in the levels of Lmp7, a component of the immunoproteasome. Increased Lmp7 levels and activity were also quantified in postmortem human brains with PD and dementia with Lewy bodies. Functionally, the immunoproteasome degrades α-synuclein aggregates and generates potentially antigenic peptides. Expression and activity of the immunoproteasome may represent testable targets to induce adaptive responses that maintain proteome integrity and modulate immune responses in protein aggregation disorders.

Abstract LB-008: KRAS engages AGO2 to enhance cellular transformation

Oncogenic mutations in RAS provide a compelling yet intractable therapeutic target. Approximately 30% of all cancers harbor activating mutations in the RAS family of small GTPase proteins, making it one of the most common oncogenic aberrations in humans. Normal RAS proteins (H, K or N-RAS) localize to the inner cell membrane and transduce extracellular growth signals by cycling between an “active” GTP-bound state and “inactive” GDP-bound state. Our understanding of RAS biology is primarily from RAS protein-effector interactions that activate a variety of effectors at the plasma membrane like RAF/PI3K/RalGDS. Yet, targeting mutant RAS proteins or its effectors / pathways remains a challenging endeavor for treating RAS driven cancers.

For a comprehensive identification of RAS interactors, we recently performed co-immunoprecipitation (Co-IP) Mass Spectrometric analysis of RAS immunoprecipitates from multiple cancer cell lines with differing KRAS mutation status. In all the cell lines studies, we uncovered an interaction between RAS and the core component of the RNA silencing machinery, Argonaute 2 (AGO2). Endogenously expressed RAS and AGO2 co-sediment and co-localize in intracellular membrane bound endoplasmic reticulum. AGO2 binds the Switch II region in KRAS, irrespective of GDP/GTP bound to RAS. Both endogenous and overexpressed mutant forms of KRAS, attenuate AGO2 related gene silencing function. Using NIH3T3 AGO2-/- cells, we demonstrate that the RAS-AGO2 interaction is required for maximal mutant KRAS expression and cellular transformation. Overall, our studies suggest that through its interaction with AGO2, RAS function extends well beyond its canonical role in intracellular signaling. We will present detailed characterization of the RAS-AGO2 interaction and its functional aspects that we have discovered so far.

Citation Format: Sunita Shankar, Sethuramasundaram Pitchiaya, Rohit Malik, Vishal Kothari, Yasuyuki Hosono, Anastasia K. Yocum, Harika Gundlapalli, Yasmine White, Ari Firestone, Xuhong Cao, Saravana M. Dhanasekaran, Jeanne Stuckey, Gideon Bollag, Kevin Shannon, Nils Walter, Chandan Kumar-Sinha, Arul M. Chinnaiyan. KRAS engages AGO2 to enhance cellular transformation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-008.

Utility of RNA-seq and GPMDB protein observation frequency for improving the sensitivity of protein identification by tandem MS

Tandem mass spectrometry (MS/MS) followed by database search is the method of choice for protein identification in proteomic studies. Database searching methods employ spectral matching algorithms and statistical models to identify and quantify proteins in a sample. In general, these methods do not utilize any information other than spectral data for protein identification. However, considering the wealth of external data available for many biological systems, analysis methods can incorporate such information to improve the sensitivity of protein identification. In this study, we present a method to utilize Global Proteome Machine Database identification frequencies and RNA-seq transcript abundances to adjust the confidence scores of protein identifications. The method described is particularly useful for samples with low-to-moderate proteome coverage (i.e., <2000–3000 proteins), where we observe up to an 8% improvement in the number of proteins identified at a 1% false discovery rate.

Characterization of KRAS rearrangements in metastatic prostate cancer

Using an integrative genomics approach called amplification breakpoint ranking and assembly analysis, we nominated KRAS as a gene fusion with the ubiquitin-conjugating enzyme UBE2L3 in the DU145 cell line, originally derived from prostate cancer metastasis to the brain. Interestingly, analysis of tissues revealed that 2 of 62 metastatic prostate cancers harbored aberrations at the KRAS locus. In DU145 cells, UBE2L3-KRAS produces a fusion protein, a specific knockdown of which attenuates cell invasion and xenograft growth. Ectopic expression of the UBE2L3-KRAS fusion protein exhibits transforming activity in NIH 3T3 fibroblasts and RWPE prostate epithelial cells in vitro and in vivo. In NIH 3T3 cells, UBE2L3-KRAS attenuates MEK/ERK signaling, commonly engaged by oncogenic mutant KRAS, and instead signals via AKT and p38 mitogen-activated protein kinase (MAPK) pathways. This is the first report of a gene fusion involving the Ras family, suggesting that this aberration may drive metastatic progression in a rare subset of prostate cancers.

SIGNIFICANCE

This is the first description of an oncogenic gene fusion of KRAS, one of the most studied proto-oncogenes. KRAS rearrangement may represent the driving mutation in a rare subset of metastatic prostate cancers, emphasizing the importance of RAS-RAF-MAPK signaling in this disease.

Mechanistic rationale for inhibition of poly(ADP-ribose) polymerase in ETS gene fusion-positive prostate cancer

Recurrent fusions of ETS genes are considered driving mutations in a diverse array of cancers, including Ewing's sarcoma, acute myeloid leukemia, and prostate cancer. We investigate the mechanisms by which ETS fusions mediate their effects, and find that the product of the predominant ETS gene fusion, TMPRSS2:ERG, interacts in a DNA-independent manner with the enzyme poly (ADP-ribose) polymerase 1 (PARP1) and the catalytic subunit of DNA protein kinase (DNA-PKcs). ETS gene-mediated transcription and cell invasion require PARP1 and DNA-PKcs expression and activity. Importantly, pharmacological inhibition of PARP1 inhibits ETS-positive, but not ETS-negative, prostate cancer xenograft growth. Finally, overexpression of the TMPRSS2:ERG fusion induces DNA damage, which is potentiated by PARP1 inhibition in a manner similar to that of BRCA1/2 deficiency.

Abstract 2803: The role of the sarcosine pathway in prostate cancer progression

Differential metabolomic alterations occur during prostate cancer progression. Exploring the metabolome of prostate cancer progression, may lead to the identification of critical biomarkers for cancer invasion and disease aggressiveness. Recently, we have identified sarcosine, an N-methyl derivative of the amino acid glycine, as a key metabolite increased most robustly in metastatic prostate cancer and detectable in the urine of men with organ-confined disease (Sreekumar et al., Nature, 2009). Here, we examined if the proximal regulatory enzymes of sarcosine, glycine-N-methyl transferase (GNMT), sarcosine dehydrogenase (SARDH) and pipecolic acid oxidase (PIPOX), play a functional role in prostate cancer progression. By tissue microarray analysis, we observed that GNMT protein levels are strongly associated with prostate cancer aggressiveness. Here, we demonstrate that stable knockdown of GNMT inhibits cell proliferation, induces apoptosis, attenuates cell invasion in Matrigel coated transwells, and blocks the anchorage-independent growth of the cancerous DU145 cells. Overexpression of GNMT in benign RWPE cells showed significantly increased cell invasion and increased sarcosine level. Importantly, knockdown of GNMT in DU145 cells also inhibited intravasation using chick chorioallantoic membrane (CAM) assay and tumor growth in xenograft assays. In contrast, we also showed that while the knockdown of sarcosine degrading enzymes, SARDH and PIPOX, induced invasion and increased sarcosine level in RWPE cells, the overexpression of these enzymes attenuated invasion and decreased sarcosine level. Further, overexpression of SARDH inhibited cell proliferation, blocked the anchorage-independent growth and also inhibited intravasation using CAM assay. Taken together, this study shows that the components of the sarcosine pathway may have potential as biomarkers of prostate cancer progression and serve as new avenues for therapeutic intervention.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2803. doi:10.1158/1538-7445.AM2011-2803

Abacus: a computational tool for extracting and pre-processing spectral count data for label-free quantitative proteomic analysis

We describe Abacus, a computational tool for extracting spectral counts from MS/MS data sets. The program aggregates data from multiple experiments, adjusts spectral counts to accurately account for peptides shared across multiple proteins, and performs common normalization steps. It can also output the spectral count data at the gene level, thus simplifying the integration and comparison between gene and protein expression data. Abacus is compatible with the widely used Trans-Proteomic Pipeline suite of tools and comes with a graphical user interface making it easy to interact with the program. The main aim of Abacus is to streamline the analysis of spectral count data by providing an automated, easy to use solution for extracting this information from proteomic data sets for subsequent, more sophisticated statistical analysis.

Alternative splice variants, a new class of protein cancer biomarker candidates: findings in pancreatic cancer and breast cancer with systems biology implications

Alternative splicing plays an important role in protein diversity without increasing genome size. Earlier thought to be uncommon, splicing appears to affect the majority of genes. Alternative splice variants have been detected at the mRNA level in many diseases. We have designed and demonstrated a discovery pipeline for alternative splice variant (ASV) proteins from tandem MS/MS datasets. We created a modified ECgene database with entries from exhaustive three-frame translation of Ensembl transcripts and gene models from ECgene, with periodic updates. The human database has 14 million entries; the mouse database, 10 million entries. We match MS/MS findings against these potential translation products to identify and quantify known and novel ASVs. In this review, we summarize findings and systems biology implications of biomarker candidates from a mouse model of human pancreatic ductal adenocarcinoma [28] and a mouse model of human Her2/neu-induced breast cancer [27]. The same approach is being applied to human tumors, plasma, and cell line studies of other cancers.

Comparison of MS(2)-only, MSA, and MS(2)/MS(3) methodologies for phosphopeptide identification

Current mass spectrometers provide a number of alternative methodologies for producing tandem mass spectra specifically for phosphopeptide analysis. In particular, generation of MS(3) spectra in a data-dependent manner upon detection of the neutral loss of a phosphoric acid in MS(2) spectra is a popular technique for circumventing the problem of poor phosphopeptide backbone fragmentation. The newer Multistage Activation method provides another option. Both these strategies require additional cycle time on the instrument and therefore reduce the number of spectra that can be measured in the same amount of time. Additional informatics is often required to make most efficient use of the additional information provided by these spectra as well. This work presents a comparison of several commonly used mass spectrometry methods for the study of phosphopeptide-enriched samples: an MS(2)-only method, a Multistage Activation method, and an MS(2)/MS(3) data-dependent neutral loss method. Several strategies for dealing effectively with the resulting MS(3) data in the latter approach are also presented and compared. The overall goal is to infer whether any one methodology performs significantly better than another for identifying phosphopeptides. On data presented here, the Multistage Activation methodology is demonstrated to perform optimally and does not result in significant loss of unique peptide identifications.

Current affairs in quantitative targeted proteomics: multiple reaction monitoring-mass spectrometry

Quantitative targeted proteomics has recently taken front stage in the proteomics community. Centered on multiple reaction monitoring-mass spectrometry (MRM-MS) methodologies, quantitative targeted proteomics is being used in the verification of global proteomics data, the discovery of lower abundance proteins, protein post-translational modifications, discrimination of select highly homologous protein isoforms and as the final step in biomarker discovery. An older methodology utilized with small molecule analysis, the proteomics community is making great technological strides to develop MRM-MS as the next method to address previously challenging issues in global proteomics experimentation, namely dynamic range, identification of post-translational modifications, sensitivity and selectivity of measurement which will undoubtedly further biomedical knowledge. This brief review will provide a general introduction of MRM-MS and highlight its novel application for targeted quantitative proteomic experimentations.

A spectral clustering approach to MS/MS identification of post-translational modifications

Unidentified tandem mass spectra typically represent 50-90% of the spectra acquired in proteomics studies. This manuscript describes a novel algorithm, "Bonanza", for clustering spectra without knowledge of peptide or protein identifications. Further analysis leverages existing peptide identifications to infer related, likely valid identifications. Significantly more spectra can be identified with this approach, including spectra with unexpected potential modifications or amino-acid substitutions.

Coupled global and targeted proteomics of human embryonic stem cells during induced differentiation

Elucidating the complex combinations of growth factors and signaling molecules that maintain pluripotency or, alternatively, promote the controlled differentiation of human embryonic stem cells (hESCs) has important implications for the fundamental understanding of human development, devising cell replacement therapies, and cancer cell biology. hESCs are commonly grown on irradiated mouse embryonic fibroblasts (MEFs) or in conditioned medium from MEFs. These culture conditions interfere with many experimental conclusions and limit the ability to perform conclusive proteomics studies. The current investigation avoided the use of MEFs or MEF-conditioned medium for hESC culture, allowing global proteomics analysis without these confounding conditions, and elucidated neural cell-specific signaling pathways involved in noggin-induced hESC differentiation. Based on these analyses, we propose the following early markers of hESC neural differentiation: collapsin response mediator proteins 2 and 4 and the nuclear autoantigenic sperm protein as a marker of pluripotent hESCs. We then developed a directed mass spectrometry assay using multiple reaction monitoring (MRM) to identify and quantify these markers and in addition the epidermal ectoderm marker cytokeratin-8. Analysis of global proteomics, quantitative RT-PCR, and MRM data led to testing the isoform interference hypothesis where redundant peptides dilute quantification measurements of homologous proteins. These results show that targeted MRM analysis on non-redundant peptides provides more exact quantification of homologous proteins. This study describes the facile transition from discovery proteomics to targeted MRM analysis and allowed us to identify and verify several potential biomarkers for hESCs during noggin-induced neural and BMP4-induced epidermal ectoderm differentiation.

Analysis of the zebrafish proteome during embryonic development

The model organism zebrafish (Danio rerio) is particularly amenable to studies deciphering regulatory genetic networks in vertebrate development, biology, and pharmacology. Unraveling the functional dynamics of such networks requires precise quantitation of protein expression during organismal growth, which is incrementally challenging with progressive complexity of the systems. In an approach toward such quantitative studies of dynamic network behavior, we applied mass spectrometric methodology and rigorous statistical analysis to create comprehensive, high quality profiles of proteins expressed at two stages of zebrafish development. Proteins of embryos 72 and 120 h postfertilization (hpf) were isolated and analyzed both by two-dimensional (2D) LC followed by ESI-MS/MS and by 2D PAGE followed by MALDI-TOF/TOF protein identification. We detected 1384 proteins from 327,906 peptide sequence identifications at 72 and 120 hpf with false identification rates of less than 1% using 2D LC-ESI-MS/MS. These included only approximately 30% of proteins that were identified by 2D PAGE-MALDI-TOF/TOF. Roughly 10% of all detected proteins were derived from hypothetical or predicted gene models or were entirely unannotated. Comparison of proteins expression by 2D DIGE revealed that proteins involved in energy production and transcription/translation were relatively more abundant at 72 hpf consistent with faster synthesis of cellular proteins during organismal growth at this time compared with 120 hpf. The data are accessible in a database that links protein identifications to existing resources including the Zebrafish Information Network database. This new resource should facilitate the selection of candidate proteins for targeted quantitation and refine systematic genetic network analysis in vertebrate development and biology.

Proteomics-based strategy to identify biomarkers and pharmacological targets in leukemias with t(4;11) translocations

Translocations and other aberrations involving the MLL (mixed lineage leukemia) gene result in aggressive forms of leukemias. Heterogeneity in partner genes, in chromosomal breakpoints, in MLL itself, and in the different partner genes results in heterogeneous fusion transcripts that can be alternatively spliced, which complicates deciphering a unifying mechanism of leukemogenesis. However, recent microarray studies completed with clinical leukemia specimens have uncovered several distinct mRNA signatures within MLL leukemia that differ from other types of leukemia. A global proteomics strategy using MV4-11 and RS4:11 cells in culture was employed to investigate possible protein signatures common to different MLL leukemias and to identify disease biomarkers and protein targets for pharmacological intervention. Initial proteomics screening experiments with two-dimensional differential in-gel electrophoresis revealed heat shock protein 90 alpha (HSP90alpha) as a potential target for pharmacological inhibition and nucleoside diphosphate kinase (nm23) as a biomarker for measuring treatment efficacy. Using a modified stable isotope labeling of amino acids in cell culture (SILAC) approach, coupled with two-dimensional liquid chromatography tandem mass spectrometry (2D-LC-MS/MS), changes in abundance for over 500 proteins were measured. In addition, decreased expression of the novel biomarker nm23 was observed during HSP90 inhibition with 17-allylamino-17-demethoxygeldanamycin (17-AAG) in the MV4-11 cell line. The present study validates the use of a global proteomics strategy to uncover novel biomarkers and pharmacological targets for leukemias with MLL translocations. Additionally, several proteins were found to be expressed in concordance with microarray studies of mRNA expression in specimens from patients showing the value in comparing mRNA transcript and proteomic profiles. This work represents one of the most comprehensive proteomics screens of MLL leukemias that have been conducted to date.

EBP, a program for protein identification using multiple tandem mass spectrometry datasets

MS/MS combined with database search methods can identify the proteins present in complex mixtures. High throughput methods that infer probable peptide sequences from enzymatically digested protein samples create a challenge in how best to aggregate the evidence for candidate proteins. Typically the results of multiple technical and/or biological replicate experiments must be combined to maximize sensitivity. We present a statistical method for estimating probabilities of protein expression that integrates peptide sequence identifications from multiple search algorithms and replicate experimental runs. The method was applied to create a repository of 797 non-homologous zebrafish (Danio rerio) proteins, at an empirically validated false identification rate under 1%, as a resource for the development of targeted quantitative proteomics assays. We have implemented this statistical method as an analytic module that can be integrated with an existing suite of open-source proteomics software.

Effect of Immunoaffinity Depletion of Human Serum during Proteomic Investigations

Controversy exists regarding the proper mining of the human serum proteome. Because of the analytical challenges of accurately measuring samples containing a very large dynamic range of protein concentrations, current practices have employed depletion of the highly abundant housekeeping serum proteins, such as albumin and immunoglobins. There is question as to the selectivity of depletion, namely, is there loss of other non abundant serum proteins along with albumin, haptoglobin and other commonly depleted proteins. In this study, human serum was analyzed with and without immunoaffinity depletion of the six most abundant proteins by multidimensional liquid chromatography tandem mass spectrometry. Two replicates of each experiment were conducted and compared against one another. In both depleted and nondepleted replicates there was a 73% and 72% overlap of identified peptides and a 64% and 78% overlap of identified proteins, respectively. Of 262 unique proteins identified in the four experiments, 82 were found in common to all four experiments, 142 unique to the depleted serum, and 38 unique to the nondepleted serum. Although serum depletion of highly abundant proteins significantly increased the number of proteins identified, both the degree of sample complexity and this depletion method resulted in a nonselective loss of other proteins.

Novel lipid hydroperoxide-derived hemoglobin histidine adducts as biomarkers of oxidative stress

Hemoglobin (Hb) adducts have long been used as dosimeters of exposure to xenobiotics and endogenously formed reactive metabolites. In this study, hemoglobin chains were separated from each other and their prosthetic heme groups and reacted with 4-oxo-2-nonenal, a major breakdown product of lipid hydroperoxides. The adducts were characterized by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-TOF/MS) analysis of the intact proteins and by a combination of liquid chromatography/electrospray ionization/tandem MS (MS/MS) and MALDI-TOF/MS/MS analysis of the tryptic peptides. Covalent modifications were found on both hemoglobin chains. The location was determined to be on H20 of the alpha-hemoglobin chain and on H(63) of the beta-hemoglobin chain. Molecular modeling revealed that these two residues were two most solvent accessible H residues present in intact Hb. The proposed reaction mechanism is based on that described for the reaction of 4-hydroxy-2-nonenal with proteins. Initial nucleophilic Michael addition is followed by hydration of the resulting aldehyde, cyclization, and two sequential dehydration reactions to give stable furan derivatives. This results in the addition of 136 Da from 4-oxo-2-nonenal to give adducts corresponding to (17)VGAH(.) AGEYGAEALER(31) from alpha-hemoglobin and (62)AH(.) GK(65) from beta-hemoglobin. These hemoglobin modifications can potentially serve as biomarkers of lipid hydroperoxide-mediated macromolecule damage and may reflect an indirect measurement of the potential for DNA damage in vivo.