Deletion of Neuronal GLT-1 in Mice Reveals Its Role in Synaptic Glutamate Homeostasis and Mitochondrial Function.

The glutamate transporter GLT-1 is highly expressed in astrocytes but also in neurons, primarily in axon terminals. We generated a conditional neuronal GLT-1 KO using synapsin 1-Cre (synGLT-1 KO) to elucidate the metabolic functions of GLT-1 expressed in neurons, here focusing on the cerebral cortex. Both synaptosomal uptake studies and electron microscopic immunocytochemistry demonstrated knockdown of GLT-1 in the cerebral cortex in the synGLT-1 KO mice. Aspartate content was significantly reduced in cerebral cortical extracts as well as synaptosomes from cerebral cortex of synGLT-1 KO compared with control littermates. 13C-Labeling of tricarboxylic acid cycle intermediates originating from metabolism of [U-13C]-glutamate was significantly reduced in synGLT-1 KO synaptosomes. The decreased aspartate content was due to diminished entry of glutamate into the tricarboxylic acid cycle. Pyruvate recycling, a pathway necessary for full glutamate oxidation, was also decreased. ATP production was significantly increased, despite unaltered oxygen consumption, in isolated mitochondria from the synGLT-1 KO. The density of mitochondria in axon terminals and perisynaptic astrocytes was increased in the synGLT-1 KO. Intramitochondrial cristae density of synGLT-1 KO mice was increased, suggesting increased mitochondrial efficiency, perhaps in compensation for reduced access to glutamate. SynGLT-1 KO synaptosomes exhibited an elevated oxygen consumption rate when stimulated with veratridine, despite a lower baseline oxygen consumption rate in the presence of glucose. GLT-1 expressed in neurons appears to be required to provide glutamate to synaptic mitochondria and is linked to neuronal energy metabolism and mitochondrial function.SIGNIFICANCE STATEMENT All synaptic transmitters need to be cleared from the extracellular space after release, and transporters are used to clear glutamate released from excitatory synapses. GLT-1 is the major glutamate transporter, and most GLT-1 is expressed in astrocytes. Only 5%-10% is expressed in neurons, primarily in axon terminals. The function of GLT-1 in axon terminals remains unknown. Here, we used a conditional KO approach to investigate the significance of the expression of GLT-1 in neurons. We found multiple abnormalities of mitochondrial function, suggesting impairment of glutamate utilization by synaptic mitochondria in the neuronal GLT-1 KO. These data suggest that GLT-1 expressed in axon terminals may be important in maintaining energy metabolism and biosynthetic activities mediated by presynaptic mitochondria.

Conditional Knockout of GLT-1 in Neurons Leads to Alterations in Aspartate Homeostasis and Synaptic Mitochondrial Metabolism in Striatum and Hippocampus.

Expression of the glutamate transporter GLT-1 in neurons has been shown to be important for synaptic mitochondrial function in the cerebral cortex. Here we determined whether neuronal GLT-1 plays a similar role in the hippocampus and striatum, using conditional GLT-1 knockout mice in which GLT-1 was inactivated in neurons by expression of synapsin-Cre (synGLT-1 KO). Ex vivo 13C-labelling using [1,2-13C]acetate, representing astrocytic metabolism, yielded increased [4,5-13C]glutamate levels, suggesting increased astrocyte-neuron glutamine transfer, in the striatum but not in the hippocampus of the synGLT-1 KO. Moreover, aspartate concentrations were reduced - 38% compared to controls in the hippocampus and the striatum of the synGLT-1 KO. Mitochondria isolated from the hippocampus of synGLT-1 KO mice exhibited a lower oxygen consumption rate in the presence of oligomycin A, indicative of a decreased proton leak across the mitochondrial membrane, whereas the ATP production rate was unchanged. Electron microscopy revealed reduced mitochondrial inter-cristae distance within excitatory synaptic terminals in the hippocampus and striatum of the synGLT-1 KO. Finally, dilution of 13C-labelling originating from [U-13C]glucose, caused by metabolism of unlabelled glutamate, was reduced in hippocampal synGLT-1 KO synaptosomes, suggesting that neuronal GLT-1 provides glutamate for synaptic tricarboxylic acid cycle metabolism. Collectively, these data demonstrate an important role of neuronal expression of GLT-1 in synaptic mitochondrial metabolism in the forebrain.

Griffithsin Retains Anti-HIV-1 Potency with Changes in gp120 Glycosylation and Complements Broadly Neutralizing Antibodies PGT121 and PGT126.

Griffithsin (Grft) is an antiviral lectin that has been shown to potently inhibit HIV-1 by binding high-mannose N-linked glycosylation sites on HIV-1 gp120. A key factor for Grft potency is glycosylation at N295 of gp120, which is directly adjacent to N332, a target glycan for an entire class of broadly neutralizing antibodies (bNAbs). Here, we unify previous work on the importance of other glycans to Grft potency against HIV-1 and Grft's role in mediating the conformational change of gp120 by mutating nearly every glycosylation site in gp120. In addition to a significant loss of Grft activity by the removal of glycosylation at N295, glycan absence at N332 or N448 was found to have moderate effects on Grft potency. Interestingly, in the absence of N295, Grft effectiveness could be improved by a mutation that results in the glycan at N448 shifting to N446, indicating that the importance of individual glycans may be related to their effect on glycosylation density. Grft's ability to alter the structure of gp120, exposing the CD4 binding site, correlated with the presence of glycosylation at N295 only in clade B strains, not clade C strains. We further demonstrate that Grft can rescue the activity of the bNAbs PGT121 and PGT126 in the event of a loss or a shift of glycosylation at N332, where the bNAbs suffer a drastic loss of potency. Despite targeting the same region, Grft in combination with PGT121 and PGT126 produced additive effects. This indicates that Grft could be an important combinational therapeutic.

Conditional deletion of the glutamate transporter GLT-1 reveals that astrocytic GLT-1 protects against fatal epilepsy while neuronal GLT-1 contributes significantly to glutamate uptake into synaptosomes.

GLT-1 (EAAT2; slc1a2) is the major glutamate transporter in the brain, and is predominantly expressed in astrocytes, but at lower levels also in excitatory terminals. We generated a conditional GLT-1 knock-out mouse to uncover cell-type-specific functional roles of GLT-1. Inactivation of the GLT-1 gene was achieved in either neurons or astrocytes by expression of synapsin-Cre or inducible human GFAP-CreERT2. Elimination of GLT-1 from astrocytes resulted in loss of ∼80% of GLT-1 protein and of glutamate uptake activity that could be solubilized and reconstituted in liposomes. This loss was accompanied by excess mortality, lower body weight, and seizures suggesting that astrocytic GLT-1 is of major importance. However, there was only a small (15%) reduction that did not reach significance of glutamate uptake into crude forebrain synaptosomes. In contrast, when GLT-1 was deleted in neurons, both the GLT-1 protein and glutamate uptake activity that could be solubilized and reconstituted in liposomes were virtually unaffected. These mice showed normal survival, weight gain, and no seizures. However, the synaptosomal glutamate uptake capacity (Vmax) was reduced significantly (40%). In conclusion, astrocytic GLT-1 performs critical functions required for normal weight gain, resistance to epilepsy, and survival. However, the contribution of astrocytic GLT-1 to glutamate uptake into synaptosomes is less than expected, and the contribution of neuronal GLT-1 to synaptosomal glutamate uptake is greater than expected based on their relative protein expression. These results have important implications for the interpretation of the many previous studies assessing glutamate uptake capacity by measuring synaptosomal uptake.

Distinct expression and function of carotenoid metabolic genes and homoeologs in developing wheat grains.

BACKGROUND: ß-carotene, the most active provitamin A molecule produced by plants, plays important roles in human nutrition and health. ß-carotene does not usually accumulate in the endosperm (i.e. flour) of mature wheat grains, which is a major food source of calories for humans. Therefore, enriching ß-carotene accumulation in wheat grain endosperm will enable a sustainable dietary supplementation of provitamin A. Several metabolic genes affecting ß-carotene accumulation have already been isolated from wheat, including phytoene synthase 1 (PSY1), lycopene ε-cyclase (LCYe) and carotenoid ß-ring hydroxylase1/2 (HYD1/2). RESULTS: In this work, we cloned and biochemically characterized two carotenoid cleavage dioxygenases (CCDs), CCD1 and CCD4, from wheat. While CCD1 homoeologs cleaved ß-apo-8'-carotenal, ß-carotene, lutein and zeaxanthin into apocarotenoid products, CCD4 homoeologs were inactive towards these substrates in in vitro assays. When analyzed by real-time qPCR, PSY1, LCYe, HYD1/2 and CCD1/4 homoeologs showed distinct expression patterns in vegetative tissues and sections of developing tetraploid and hexaploid wheat grains, suggesting that carotenoid metabolic genes and homoeologs are differentially regulated at the transcriptional level in wheat. CONCLUSIONS: The CCD1/4 enzyme activity and the spatial-temporal gene expression data provide critical insights into the specific carotenoid metabolic gene homoeologs that control ß-carotene accumulation in wheat grain endosperm, thus establishing the knowledge base for generation of wheat varieties with enhanced ß-carotene in the endosperm through breeding and genome editing approaches.

Role of the major glutamate transporter GLT1 in nucleus accumbens core versus shell in cue-induced cocaine-seeking behavior.

Relapse to cocaine-seeking behavior requires an increase in nucleus accumbens (NAc) core glutamate transmission. Decreased expression of glutamate type I transporter (GLT1), which is responsible for >90% of glutamate clearance, occurs in the core of rats withdrawn from cocaine self-administration, while treatment with ceftriaxone, a ß-lactam antibiotic previously shown to increase GLT1 expression and function in rodents, upregulates GLT1 and attenuates cue-induced cocaine reinstatement. Here, we tested the effects of increasing GLT1 expression on cue-induced cocaine seeking in rats exposed to either limited (2 h/d) or extended (6 h/d) cocaine access followed by short (2 d) or long (45 d) withdrawal periods. Treatment with ceftriaxone (200 mg/kg, i.p.) upregulated core GLT1 expression and attenuated cue-induced cocaine-seeking behavior only in rats exposed to long withdrawal periods, with a greater effect in the extended-access condition. Pearson's correlation revealed GLT1 expression in core to be inversely correlated with cue-induced cocaine-seeking behavior. To localize the effects of GLT1 upregulation within NAc, we tested the hypothesis that blockade of GLT1 in NAc core, but not shell, would reverse the ceftriaxone-mediated effect. Rats withdrawn from cocaine self-administration were treated with the same dose of ceftriaxone followed by intracore or intrashell infusions of one of two GLT1 blockers, dihydrokainic acid (500 µM) or DL-threo-ß-benzyloxyaspartate (250 µM), or saline. Our results reveal that the ceftriaxone-mediated attenuation of cue-induced cocaine reinstatement is reversed by GLT1 blockade in core, but not shell, and further implicate core GLT1 as a potential therapeutic target for cocaine relapse.

Development of entrustable professional activities for emergency medicine medical education fellowships: A modified Delphi study.

Background: It is essential that medical education (MedEd) fellows achieve desired outcomes prior to graduation. Despite the increase in postgraduate MedEd fellowships in emergency medicine (EM), there is no consistently applied competency framework. We sought to develop entrustable professional activities (EPAs) for EM MedEd fellows. Methods: From 2021 to 2022, we used a modified Delphi method to achieve consensus for EPAs. EM education experts generated an initial list of 173 EPAs after literature review. In each Delphi round, panelists were asked to make a binary choice of whether to include the EPA. We determined an inclusion threshold of 70% agreement a priori. After the first round, given the large number of EPAs meeting inclusion threshold, panelists were instructed to vote whether each EPA should be included in the "20 most important" EPAs for a MedEd fellowship. Modifications were made between rounds based on expert feedback. We calculated descriptive statistics. Results: Seventeen experts completed four Delphi rounds each with 100% response. After Round 1, 87 EPAs were eliminated and two were combined. Following Round 2, 46 EPAs were eliminated, seven were combined, and three were included in the final list. After the third round, one EPA was eliminated and 13 were included. After the fourth round, 11 EPAs were eliminated. The final list consisted of 16 EPAs in domains of career development, education theory and methods, research and scholarship, and educational program administration. Conclusions: We developed a list of 16 EPAs for EM MedEd fellowships, the first step in implementing competency-based MedEd.

The Antiviral Activity of the Lectin Griffithsin against SARS-CoV-2 Is Enhanced by the Presence of Structural Proteins.

Although COVID-19 transmission has been reduced by the advent of vaccinations and a variety of rapid monitoring techniques, the SARS-CoV-2 virus itself has shown a remarkable ability to mutate and persist. With this long track record of immune escape, researchers are still exploring prophylactic treatments to curtail future SARS-CoV-2 variants. Specifically, much focus has been placed on the antiviral lectin Griffithsin in preventing spike protein-mediated infection via the hACE2 receptor (direct infection). However, an oft-overlooked aspect of SARS-CoV-2 infection is viral capture by attachment receptors such as DC-SIGN, which is thought to facilitate the initial stages of COVID-19 infection in the lung tissue (called trans-infection). In addition, while immune escape is dictated by mutations in the spike protein, coronaviral virions also incorporate M, N, and E structural proteins within the particle. In this paper, we explored how several structural facets of both the SARS-CoV-2 virion and the antiviral lectin Griffithsin can affect and attenuate the infectivity of SARS-CoV-2 pseudovirus. We found that Griffithsin was a better inhibitor of hACE2-mediated direct infection when the coronaviral M protein is present compared to when it is absent (possibly providing an explanation regarding why Griffithsin shows better inhibition against authentic SARS-CoV-2 as opposed to pseudotyped viruses, which generally do not contain M) and that Griffithsin was not an effective inhibitor of DC-SIGN-mediated trans-infection. Furthermore, we found that DC-SIGN appeared to mediate trans-infection exclusively via binding to the SARS-CoV-2 spike protein, with no significant effect observed when other viral proteins (M, N, and/or E) were present. These results provide etiological data that may help to direct the development of novel antiviral treatments, either by leveraging Griffithsin binding to the M protein as a novel strategy to prevent SARS-CoV-2 infection or by narrowing efforts to inhibit trans-infection to focus on DC-SIGN binding to SARS-CoV-2 spike protein.

Further Characterization of Multi-Organ DEARE and Protection by 16,16 Dimethyl Prostaglandin E2 in a Mouse Model of the Hematopoietic Acute Radiation Syndrome.

Survivors of acute radiation exposure suffer from the delayed effects of acute radiation exposure (DEARE), a chronic condition affecting multiple organs, including lung, kidney, heart, gastrointestinal tract, eyes, and brain, and often causing cancer. While effective medical countermeasures (MCM) for the hematopoietic-acute radiation syndrome (H-ARS) have been identified and approved by the FDA, development of MCM for DEARE has not yet been successful. We previously documented residual bone marrow damage (RBMD) and progressive renal and cardiovascular DEARE in murine survivors of H-ARS, and significant survival efficacy of 16,16-dimethyl prostaglandin E2 (dmPGE2) given as a radioprotectant or radiomitigator for H-ARS. We now describe additional DEARE (physiological and neural function, progressive fur graying, ocular inflammation, and malignancy) developing after sub-threshold doses in our H-ARS model, and detailed analysis of the effects of dmPGE2 administered before (PGE-pre) or after (PGE-post) lethal total-body irradiation (TBI) on these DEARE. Administration of PGE-pre normalized the twofold reduction of white blood cells (WBC) and lymphocytes seen in vehicle-treated survivors (Veh), and increased the number of bone marrow (BM) cells, splenocytes, thymocytes, and phenotypically defined hematopoietic progenitor cells (HPC) and hematopoietic stem cells (HSC) to levels equivalent to those in non-irradiated age-matched controls. PGE-pre significantly protected HPC colony formation ex vivo by >twofold, long term-HSC in vivo engraftment potential up to ninefold, and significantly blunted TBI-induced myeloid skewing. Secondary transplantation documented continued production of LT-HSC with normal lineage differentiation. PGE-pre reduced development of DEARE cardiovascular pathologies and renal damage; prevented coronary artery rarefication, blunted progressive loss of coronary artery endothelia, reduced inflammation and coronary early senescence, and blunted radiation-induced increase in blood urea nitrogen (BUN). Ocular monocytes were significantly lower in PGE-pre mice, as was TBI-induced fur graying. Increased body weight and decreased frailty in male mice, and reduced incidence of thymic lymphoma were documented in PGE-pre mice. In assays measuring behavioral and cognitive functions, PGE-pre reduced anxiety in females, significantly blunted shock flinch response, and increased exploratory behavior in males. No effect of TBI was observed on memory in any group. PGE-post, despite significantly increasing 30-day survival in H-ARS and WBC and hematopoietic recovery, was not effective in reducing TBI-induced RBMD or any other DEARE. In summary, dmPGE2 administered as an H-ARS MCM before lethal TBI significantly increased 30-day survival and ameliorated RBMD and multi-organ and cognitive/behavioral DEARE to at least 12 months after TBI, whereas given after TBI, dmPGE2 enhances survival from H-ARS but has little impact on RBMD or other DEARE.

Microglial knockdown does not affect acute withdrawal but delays analgesic tolerance from oxycodone in male and female C57BL/6J mice.

Opioid Use Disorder (OUD) affects approximately 8%-12% of the population. In dependent individuals, abrupt cessation of opioid taking results in adverse withdrawal symptoms that reinforce drug taking behavior. Considerable unmet clinical need exists for new pharmacotherapies to treat opioid withdrawal as well as improve long-term abstinence. The neuroimmune system has received much scientific attention in recent years as a potential therapeutic target to combat various neurodegenerative and psychiatric disorders including addiction. However, the specific contribution of microglia has not been investigated in oxycodone dependence. Chronic daily treatment with the CSF1R inhibitor Pexidartinib (PLX3397) was administered to knockdown microglia expression and evaluate consequences on analgesia and on naloxone induced withdrawal from oxycodone. In vivo results indicated that an approximately 40% reduction in brain IBA1 staining was achieved in the PLX treatment group, which was associated with a delay in the development of analgesic tolerance to oxycodone and maintained antinociceptive efficacy. Acute withdrawal behavioral symptoms, brain astrocyte expression, and levels of many neuroinflammatory markers were not affected by PLX treatment. KC/GRO (also known as CXCL1) was significantly enhanced in the somatosensory cortex in oxycodone-treated mice receiving PLX. Microglial knock-down did not affect the expression of naloxoneinduced opioid withdrawal but affected antinociceptive responsivity. The consequences of increased KC/GRO expression within the somatosensory cortex due to microglial reduction during opioid dependence are unclear but may be important for neural pathways mediating opioid-induced analgesia.

Glutamate homeostasis and dopamine signaling: Implications for psychostimulant addiction behavior.

Cocaine, amphetamine, and methamphetamine abuse disorders are serious worldwide health problems. To date, there are no FDA-approved medications for the treatment of these disorders. Elucidation of the biochemical underpinnings contributing to psychostimulant addiction is critical for the development of effective therapies. Excitatory signaling and glutamate homeostasis are well known pathophysiological substrates underlying addiction-related behaviors spanning multiple types of psychostimulants. To alleviate relapse behavior to psychostimulants, considerable interest has focused on GLT-1, the major glutamate transporter in the brain. While many brain regions are implicated in addiction behavior, this review focuses on two regions well known for their role in mediating the effects of cocaine and amphetamines, namely the nucleus accumbens (NAc) and the ventral tegmental area (VTA). In addition, because many investigators have utilized Cre-driver lines to selectively control gene expression in defined cell populations relevant for psychostimulant addiction, we discuss potential off-target effects of Cre-recombinase that should be considered in the design and interpretation of such experiments.

Huntington's disease pattern of transcriptional dysregulation in the absence of mutant huntingtin is produced by knockout of neuronal GLT-1.

GLT-1 is the major glutamate transporter in the brain, and is expressed in astrocytes and in axon terminals in the hippocampus, cortex, and striatum. Neuronal GLT-1 accounts for only 5-10% of total brain GLT-1 protein, and its function is uncertain. In HD, synaptic dysfunction of the corticostriate synapse is well-established. Transcriptional dysregulation is a key feature of HD. We hypothesized that deletion of neuronal GLT-1, because it is expressed in axon terminals in the striatum, might produce a synaptopathy similar to that present in HD. If true, then some of the gene expression changes observed in HD might also be observed in the neuronal GLT-1 knockout. In situ hybridization using 33P labeled oligonucleotide probes was carried out to assess localization and expression of a panel of genes known to be altered in expression in HD. We found changes in the expression of cannabinoid receptors 1 and 2, preproenkaphalin, and PDE10A in the striatum of mice in which the GLT-1 gene was inactivated in neurons by expression of synapsin-Cre, compared to wild-type littermates. These changes in expression were observed at 12 weeks of age but not at 6 weeks of age. No changes in DARPP-32, PDE1B, NGFIA, or ß-actin expression were observed. In addition, we found widespread alteration in expression of the dynamin 1 gene. The changes in expression in the neuronal GLT-1 knockout of genes thought to exemplify HD transcriptional dysregulation suggest an overlap in the synaptopathy caused by neuronal GLT-1 deletion and HD. These data further suggest that specific changes in expression of cannabinoid receptors, preproenkephalin, and PDE10A, considered to be the hallmark of HD transcriptional dysregulation, may be produced by an abnormality of glutamate homeostasis under the regulation of neuronal GLT-1, or a synaptic disturbance caused by that abnormality, independently of mutation in huntingtin.

Behavioral phenotyping and dopamine dynamics in mice with conditional deletion of the glutamate transporter GLT-1 in neurons: resistance to the acute locomotor effects of amphetamine.

RATIONALE: GLT-1 is the major glutamate transporter in the brain and is expressed predominantly in astrocytes but is also present in excitatory axon terminals. To understand the functional significance of GLT-1 expressed in neurons, we generated a conditional GLT-1 knockout mouse and inactivated GLT-1 in neurons using Cre-recombinase expressed under the synapsin 1 promoter, (synGLT-1 KO). OBJECTIVES: Abnormalities of glutamate homeostasis have been shown to affect hippocampal-related behaviors including learning and memory as well as responses to drugs of abuse. Here, we asked whether deletion of GLT-1 specifically from neurons would affect behaviors that assessed locomotor activity, cognitive function, sensorimotor gating, social interaction, as well as amphetamine-stimulated locomotor activity. METHODS/RESULTS: We found that the neuronal GLT-1 KO mice performed similarly to littermate controls in the behavioral tests we studied. Although performance in open field testing was normal, the acute locomotor response to amphetamine was significantly blunted in the synGLT-1 KO (40% of control). We found no change in amphetamine-stimulated extracellular dopamine in the medial shell of the nucleus accumbens, no change in electrically stimulated or amphetamine-induced dopamine release, and no change in dopamine tissue content. CONCLUSIONS: These results support the view that GLT-1 expression in neurons is required for amphetamine-induced behavioral activation, and suggest that this phenotype is not produced through a change in dopamine uptake or release. Although GLT-1 is highly expressed in neurons in the CA3 region of the hippocampus, the tests used in this study were not able to detect a behavioral phenotype referable to hippocampal dysfunction.

Provider support of spontaneous pushing during the second stage of labor.

OBJECTIVE: To describe the association between provider communication and actual maternal pushing behavior in second-stage labor and to test differences in length of second stage and total maternal pushing time by maternal pushing behavior. DESIGN: Descriptive. SETTING: Midwest hospital birth unit. PARTICIPANTS: Twenty primigravidas who gave birth vaginally. INTERVENTION: Type of provider communication (supportive of spontaneous or directed pushing). MAIN OUTCOME MEASURE: Maternal pushing behavior (spontaneous or directed) documented by videotape review. RESULTS: The percentage of provider communication supporting spontaneous pushing versus directed pushing and the percentage of actual spontaneous versus directed maternal pushing behavior were associated (Pearson r = .80, p = .001, for spontaneous and r = .89, p = .001, for directed). Neither duration of second stage (t = .06, p = .95) nor time spent pushing (t = .15, p = .89) differed by spontaneous versus directed pushing style. CONCLUSION: The proportion of spontaneous pushing by the birthing woman was positively and significantly associated with the proportion of caregiver communication supporting and encouraging spontaneous pushing. Importantly, spontaneous pushing did not significantly lengthen the duration of second-stage labor or total time spent pushing.

Identification of emotionally ambiguous interpersonal stimuli among dysphoric and nondysphoric individuals.

This study examined whether dysphoria influences the identification of non-ambiguous and ambiguous facial expressions of emotion. Dysphoric and non-dysphoric college students viewed a series of human faces expressing sadness, happiness, anger, and fear that were morphed with each other to varying degrees. Dysphoric and non-dysphoric individuals identified prototypical emotional expressions similarly. However, when viewing ambiguous faces, dysphoric individuals were more likely to identify sadness when mixed with happiness than non-dysphoric individuals. A similar but less robust pattern was observed for facial expressions that combined fear and happiness. No group differences in emotion identification were observed for faces that combined sadness and anger or fear and anger. Dysphoria appears to enhance the identification of negative emotion in others when positive emotion is also present. This tendency may contribute to some of the interpersonal difficulties often experienced by dysphoric individuals.

Subtyping women with bulimia nervosa along dietary and negative affect dimensions: further evidence of reliability and validity.

Studies have found that individuals with bulimia nervosa can be classified into dietary and dietary-negative affect subtypes and that the latter exhibit greater eating pathology, psychiatric comorbidity, and functional impairment; a more protracted clinical course; and a worse treatment response. In this report, the authors describe 2 prospective studies that found that young women with threshold (n = 48) and subthreshold (n = 83) bulimic pathology can be classified into dietary and dietary-negative affect subtypes; that two subtyping approaches produced similar results (mean kappa = .94); that the subtyping distinction showed 4-week test-retest reliability (kappa = .61); and that the dietary-negative affect subtype showed greater eating pathology, emotional distress, functional impairment, treatment seeking, and lower likelihood of recovery over 6-month and 3-year follow-ups than the dietary subtype. The dieting-negative affect subtyping distinction evidenced greater test-retest reliability and concurrent and predictive validity than did the purging-nonpurging subtyping distinction. The additional evidence for the reliability and validity of this subtyping scheme, particularly the prognostic utility, suggests it is worth additional inquiry.