Application of glutamate weighted CEST in brain imaging of nicotine dependent participants in vivo at 7T.

INTRODUCTION: With nicotine dependence being a significant healthcare issue worldwide there is a growing interest in developing novel therapies and diagnostic aids to assist in treating nicotine addiction. Glutamate (Glu) plays an important role in cognitive function regulation in a wide range of conditions including traumatic brain injury, aging, and addiction. Chemical exchange saturation transfer (CEST) imaging via ultra-high field MRI can image the exchange of certain saturated labile protons with the surrounding bulk water pool, making the technique a novel tool to investigate glutamate in the context of addiction. The aim of this work was to apply glutamate weighted CEST (GluCEST) imaging to study the dorsal anterior cingulate cortex (dACC) in a small population of smokers and non-smokers to determine its effectiveness as a biomarker of nicotine use. METHODS: 2D GluCEST images were acquired on 20 healthy participants: 10 smokers (ages 29-50) and 10 non-smokers (ages 25-69), using a 7T MRI system. T1-weighted images were used to segment the GluCEST images into white and gray matter tissue and further into seven gray matter regions. Wilcoxon rank-sum tests were performed, comparing mean GluCEST contrast between smokers and non-smokers across brain regions. RESULTS: GluCEST levels were similar between smokers and non-smokers; however, there was a moderate negative age dependence (R2 = 0.531) in smokers within the cingulate gyrus. CONCLUSION: Feasibility of GluCEST imaging was demonstrated for in vivo investigation of smokers and non-smokers to assess glutamate contrast differences as a potential biomarker with a moderate negative age correlation in the cingulate gyrus suggesting reward network involvement.

Disclosure and Help-Seeking Experiences of Sexual and Gender Minority Victims of Intimate Partner Violence: A Mixed-Methods Study.

Sexual and gender minorities assigned female at birth (SGM-AFAB) experience high rates of intimate partner violence (IPV), with negative effects on health and well-being. Disclosure of and help-seeking for IPV can support the well-being of IPV survivors, yet are understudied among SGM-AFAB people. To better understand the IPV disclosure and help-seeking experiences in this population, we conducted semi-structured interviews with 41 SGM-AFAB young adults who experienced physical, sexual, or severe psychological IPV. Qualitative analyses explored to whom SGM-AFAB disclosed IPV, barriers to disclosure/help-seeking, the types of responses received, and perceived helpfulness of responses. Exploratory mixed methods analyses assessed frequency of code endorsement, demographic differences, and associations among codes. Three-quarters of participants disclosed IPV, though rates were lower for sexual and physical than psychological IPV and very few sought help from formal sources. The most common barriers to disclosure were not viewing the IPV as abuse and anticipation of negative responses, often due to stigma; other participants described inability to access formal help and concerns about SGM incompetence in those services. Most actual responses received were considered helpful, including emotional support, labeling the IPV as unhealthy, nonjudgmental listening, actions to stop the IPV, and practical support. Minimizing IPV or criticizing the victim was common unhelpful response; advice to end the relationship was considered helpful and unhelpful. Whereas 92% of friend responses were described as helpful, around half of family (56%) and therapist (62%) responses were helpful. Findings suggest that efforts to increase access to culturally affirmative services and educate SGM youth to recognize IPV in their relationships may help promote help-seeking and well-being among SGM-AFAB IPV survivors.

Demographic and Minority Stress Risk Factors for Obesity Among Sexual Minority Youth Assigned Female at Birth.

Purpose: Sexual minority youth (adolescents and young adults) assigned female at birth (SM-AFAB) are at disproportionate risk of developing obesity compared with heterosexual cisgender youth AFAB. Grounded in minority stress theory, this study aimed to identify potential risk factors for obesity among SM-AFAB youth to inform the development of prevention and intervention efforts for this high-risk population. Methods: Data were collected in 2017 from 367 SM-AFAB youth (ages 16-20 years). Multinominal logistic regression was used to assess cross-sectional associations of race/ethnicity, sexuality, gender identity, household income, and sexual minority (SM) stressors (internalized stigma, microaggressions, and victimization) with weight status (normal, overweight, and obese). Results: Roughly half (53.1%) of participants' body mass index were in the normal weight range, with 24.8% in the overweight range and 22.1% in the obese range. Rates of obesity in Black and Latinx participants were 3-4.5 times those of White participants. Bisexual, pansexual, and queer individuals were at greater risk for obesity than gay/lesbian participants; only bisexual participants were at higher risk for overweight. Participants with a household income <$20,000 and between $20,000 and $39,000 were at greater risk for obesity than participants with household income >$80,000. Microaggressions were positively associated with obesity. Conclusion: Findings highlight risk for obesity among SM-AFAB youth, particularly for those who identify as racial minority, as low income, as being attracted to more than one gender, and for those who experience high levels of anti-SM microaggressions. Targeted obesity prevention and treatment programs should consider the unique needs, challenges, and strengths of SM-AFAB youth.

Rural living environment predicts social anxiety in transgender and gender nonconforming individuals across Canada and the United States.

Transgender and gender nonconforming (TGNC) individuals frequently confront discrimination, rejection, and violence. Such experiences may put TGNC individuals at risk for minority stress and associated psychiatric symptoms. Protective factors like social support, pride in one's gender identity, or connectedness to similar others may make TGNC individuals less vulnerable to psychiatric symptoms, and the presence of risk and protective factors may vary depending on living environment. This study examined the relationship of living environment (urban vs. suburban vs. small-town/rural) to social anxiety (SA) in a sample of 902 TGNC individuals who participated in the Trans Health Survey. Analysis of variance revealed a significant difference in SA across living environments. Those living in small-town/rural environments reported significantly higher levels of SA compared to those living in urban environments. There was a trend-level difference in SA in suburban compared to urban environments. Linear regression analyses revealed that living environment significantly moderated the relationship between social support and SA. Higher social support was more protective against elevated SA in urban and suburban than in small-town/rural environments. This study is the first to demonstrate the experience of elevated SA among TGNC individuals living in rural environments. Implications and future directions for research are discussed.

A transgenic mouse model demonstrates a dominant negative effect of a point mutation in the RPS19 gene associated with Diamond-Blackfan anemia.

Diamond Blackfan anemia (DBA) is an inherited erythroblastopenia associated with mutations in at least 8 different ribosomal protein genes. Mutations in the gene encoding ribosomal protein S19 (RPS19) have been identified in approximately 25% of DBA families. Most of these mutations disrupt either the translation or stability of the RPS19 protein and are predicted to cause DBA by haploinsufficiency. However, approximately 30% of RPS19 mutations are missense mutations that do not alter the stability of the RPS19 protein and are hypothesized to act by a dominant negative mechanism. To formally test this hypothesis, we generated a transgenic mouse model expressing an RPS19 mutation in which an arginine residue is replaced with a tryptophan residue at codon 62 (RPS19R62W). Constitutive expression of RPS19R62W in developing mice was lethal. Conditional expression of RPS19R62W resulted in growth retardation, a mild anemia with reduced numbers of erythroid progenitors, and significant inhibition of terminal erythroid maturation, similar to DBA. RNA profiling demonstrated more than 700 dysregulated genes belonging to the same pathways that are disrupted in RNA profiles of DBA patient cells. We conclude that RPS19R62W is a dominant negative DBA mutation.

Functional analysis of a novel cis-acting regulatory region within the human ankyrin gene (ANK-1) promoter.

The characterization of atypical mutations in loci associated with diseases is a powerful tool to discover novel regulatory elements. We previously identified a dinucleotide deletion in the human ankyrin-1 gene (ANK-1) promoter that underlies ankyrin-deficient hereditary spherocytosis. The presence of the deletion was associated with a decrease in promoter function both in vitro and in vivo establishing it as a causative hereditary spherocytosis mutation. The dinucleotide deletion is located in the 5' untranslated region of the ANK-1 gene and disrupts the binding of TATA binding protein and TFIID, components of the preinitiation complex. We hypothesized that the nucleotides surrounding the mutation define an uncharacterized regulatory sequence. To test this hypothesis, we generated a library of more than 16,000 ANK-1 promoters with degenerate sequence around the mutation and cloned the functional promoter sequences after cell-free transcription. We identified the wild type and three additional sequences, from which we derived a consensus. The sequences were shown to be functional in cell-free transcription, transient-transfection, and transgenic mouse assays. One sequence increased ANK-1 promoter function 5-fold, while randomly chosen sequences decreased ANK-1 promoter function. Our results demonstrate a novel functional motif in the ANK-1 promoter.

High levels of human gamma-globin are expressed in adult mice carrying a transgene of the Brazilian type of hereditary persistence of fetal hemoglobin ((A)gamma -195).

Hereditary persistence of fetal hemoglobin (HPFH) is characterized by increased levels of Hb F during adult life. Nondeletional forms of HPFH are characterized by single base mutations in the (A)gamma and (G)gamma promoters, resulting in an increase of Hb F ranging from 3 to 20% in heterozygotes. Many point mutations in this region have been described, including the (A)gamma -195 (C>G) mutation that causes the Brazilian type of HPFH (HPFH-B). To better understand this mechanism, we have developed HPFH-B transgenic mice. mRNA levels of human gamma-globin of -195 transgenic mice were clearly higher when compared with control transgenic mice bearing a wild type sequence of the gamma promoter. Thus, our data indicate that the -195 mutation is the unique cause of elevation of Hb F in Brazilian HPFH. These results could provide us with an opportunity to study the modifying effects of the Hb F in the phenotype of sickle cell disease and beta-thalassemia (beta-thal).

Adducin forms a bridge between the erythrocyte membrane and its cytoskeleton and regulates membrane cohesion.

The erythrocyte membrane skeleton is the best understood cytoskeleton. Because its protein components have homologs in virtually all other cells, the membrane serves as a fundamental model of biologic membranes. Modern textbooks portray the membrane as a 2-dimensional spectrin-based membrane skeleton attached to a lipid bilayer through 2 linkages: band 3-ankyrin-beta-spectrin and glycophorin C-protein 4.1-beta-spectrin.(1-7) Although evidence supports an essential role for the first bridge in regulating membrane cohesion, rupture of the glycophorin C-protein 4.1 interaction has little effect on membrane stability.(8) We demonstrate the existence of a novel band 3-adducin-spectrin bridge that connects the spectrin/actin/protein 4.1 junctional complex to the bilayer. As rupture of this bridge leads to spontaneous membrane fragmentation, we conclude that the band 3-adducin-spectrin bridge is important to membrane stability. The required relocation of part of the band 3 population to the spectrin/actin junctional complex and its formation of a new bridge with adducin necessitates a significant revision of accepted models of the erythrocyte membrane.