Cryo-EM Structures and Regulation of Arabinofuranosyltransferase AftD from Mycobacteria.

Mycobacterium tuberculosis causes tuberculosis, a disease that kills over 1 million people each year. Its cell envelope is a common antibiotic target and has a unique structure due, in part, to two lipidated polysaccharides-arabinogalactan and lipoarabinomannan. Arabinofuranosyltransferase D (AftD) is an essential enzyme involved in assembling these glycolipids. We present the 2.9-Å resolution structure of M. abscessus AftD, determined by single-particle cryo-electron microscopy. AftD has a conserved GT-C glycosyltransferase fold and three carbohydrate-binding modules. Glycan array analysis shows that AftD binds complex arabinose glycans. Additionally, AftD is non-covalently complexed with an acyl carrier protein (ACP). 3.4- and 3.5-Å structures of a mutant with impaired ACP binding reveal a conformational change, suggesting that ACP may regulate AftD function. Mutagenesis experiments using a conditional knockout constructed in M. smegmatis confirm the essentiality of the putative active site and the ACP binding for AftD function.

How consumer digital signals are reshaping the customer journey.

Marketers are adopting increasingly sophisticated ways to engage with customers throughout their journeys. We extend prior perspectives on the customer journey by introducing the role of digital signals that consumers emit throughout their activities. We argue that the ability to detect and act on consumer digital signals is a source of competitive advantage for firms. Technology enables firms to collect, interpret, and act on these signals to better manage the customer journey. While some consumers' desire for privacy can restrict the opportunities technology provides marketers, other consumers' desire for personalization can encourage the use of technology to inform marketing efforts. We posit that this difference in consumers' willingness to emit observable signals may hinge on the strength of their relationship with the firm. We next discuss factors that may shift consumer preferences and consequently affect the technology-enabled opportunities available to firms. We conclude with a research agenda that focuses on consumers, firms, and regulators.

Gremlin-1 potentiates the dedifferentiation of VSMC in early stages of atherosclerosis.

Vascular smooth muscle cells (VSMC) are highly specialized, and exhibit a contractile phenotype when mature and fully differentiated, being responsible for vessel homeostasis and blood pressure control. In response to pro-atherogenic stimuli VSMC alter their state of differentiation, increase proliferation and migration, resulting in SMC phenotypes ranging from contractile to synthetic. This variability is observed in cell morphology and expression level of marker genes for differentiation status. There is growing evidence that bone morphogenetic protein (BMP) signaling is involved in vascular diseases, including atherosclerosis. Here, we evaluated in vitro the role of specific agonists/antagonists belonging to the BMP pathway on dedifferentiation of VSMC harvested during early stages of atherosclerosis. RESULTS: Comparing primary VSMC isolated from aortas of susceptible ApoE-/- animals fed 8 weeks of western diet with their littermate controls fed usual diet, we observed that recombinant BMP4 was able to reduce SM22-alpha and alpha actin gene expression indicating dedifferentiation was under way. Unexpectedly, treatment with recombinant Gremlin-1, a known BMP antagonist, also reduced 4-6.5 folds gene expression of SM22-alpha, alpha-actin and, calponin, exclusively in VSMC from ApoE-/- animals, independently on the diet consumed. CONCLUSION: Our data show that BMP4 is capable of modulating of SM22-alpha and alpha actin gene expression, indicative of cell dedifferentiation in VSMC. Additionally, we report for first time that Gremlin-1 acts independently of the BMP pathway and selectively on VSMC from susceptible animals, reducing the expression of all genes evaluated.

T Cell-Derived IL-10 Impairs Host Resistance to Mycobacterium tuberculosis Infection.

Tuberculosis (TB), caused by Mycobacterium tuberculosis infection, is a leading cause of mortality and morbidity, causing ∼1.5 million deaths annually. CD4+ T cells and several cytokines, such as the Th1 cytokine IFN-γ, are critical in the control of this infection. Conversely, the immunosuppressive cytokine IL-10 has been shown to dampen Th1 cell responses to M. tuberculosis infection impairing bacterial clearance. However, the critical cellular source of IL-10 during M. tuberculosis infection is still unknown. Using IL-10 reporter mice, we show in this article that during the first 14 d of M. tuberculosis infection, the predominant cells expressing IL-10 in the lung were Ly6C+ monocytes. However, after day 21 postinfection, IL-10-expressing T cells were also highly represented. Notably, mice deficient in T cell-derived IL-10, but not mice deficient in monocyte-derived IL-10, showed a significant reduction in lung bacterial loads during chronic M. tuberculosis infection compared with fully IL-10-competent mice, indicating a major role for T cell-derived IL-10 in TB susceptibility. IL-10-expressing cells were detected among both CD4+ and CD8+ T cells, expressed high levels of CD44 and Tbet, and were able to coproduce IFN-γ and IL-10 upon ex vivo stimulation. Furthermore, during M. tuberculosis infection, Il10 expression in CD4+ T cells was partially regulated by both IL-27 and type I IFN signaling. Together, our data reveal that, despite the multiple immune sources of IL-10 during M. tuberculosis infection, activated effector T cells are the major source accounting for IL-10-induced TB susceptibility.

Disruption of IL-21 signaling affects T cell-B cell interactions and abrogates protective humoral immunity to malaria.

Interleukin-21 signaling is important for germinal center B-cell responses, isotype switching and generation of memory B cells. However, a role for IL-21 in antibody-mediated protection against pathogens has not been demonstrated. Here we show that IL-21 is produced by T follicular helper cells and co-expressed with IFN-γ during an erythrocytic-stage malaria infection of Plasmodium chabaudi in mice. Mice deficient either in IL-21 or the IL-21 receptor fail to resolve the chronic phase of P. chabaudi infection and P. yoelii infection resulting in sustained high parasitemias, and are not immune to re-infection. This is associated with abrogated P. chabaudi-specific IgG responses, including memory B cells. Mixed bone marrow chimeric mice, with T cells carrying a targeted disruption of the Il21 gene, or B cells with a targeted disruption of the Il21r gene, demonstrate that IL-21 from T cells signaling through the IL-21 receptor on B cells is necessary to control chronic P. chabaudi infection. Our data uncover a mechanism by which CD4+ T cells and B cells control parasitemia during chronic erythrocytic-stage malaria through a single gene, Il21, and demonstrate the importance of this cytokine in the control of pathogens by humoral immune responses. These data are highly pertinent for designing malaria vaccines requiring long-lasting protective B-cell responses.

IL-27 promotes IL-10 production by effector Th1 CD4+ T cells: a critical mechanism for protection from severe immunopathology during malaria infection.

Infection with the malaria parasite, Plasmodium, is characterized by excessive inflammation. The establishment of a precise balance between the pro- and anti-inflammatory responses is critical to guarantee control of the parasite and survival of the host. IL-10, a key regulatory cytokine produced by many cells of the immune system, has been shown to protect mice against pathology during acute Plasmodium0 chabaudi chabaudi AS model of malaria. However, the critical cellular source of IL-10 is still unknown. In this article, we demonstrate that T cell-derived IL-10 is necessary for the control of pathology during acute malaria, as mice bearing specific deletion of Il10 in T cells fully reproduce the phenotype observed in Il10(-)(/)(-) mice, with significant weight loss, decline in temperature, and increased mortality. Furthermore, we show that IFN-γ(+) Th1 cells are the main producers of IL-10 throughout acute infection, expressing high levels of CD44 and ICOS, and low levels of CD127. Although Foxp3(+) regulatory CD4(+) T cells produce IL-10 during infection, highly activated IFN-γ(+) Th1 cells were shown to be the essential and sufficient source of IL-10 to guarantee protection against severe immune-mediated pathology. Finally, in this model of malaria, we demonstrate that the generation of protective IL10(+)IFN-γ(+) Th1 cells is dependent on IL-27 signaling and independent of IL-21.

Aging and HIV/AIDS: neurocognitive implications for older HIV-positive Latina/o adults.

In recent years, HIV/AIDS populations have become older and increasingly more ethnically diverse. Concurrently, the prevalence of HIV-related neurocognitive (NC) impairment remains high. This study examined the effects of age and ethnicity on NC function in HIV-positive adults. The sample (N = 126; 84 Latina/o and 42 Non-Hispanic White) completed a comprehensive NC battery. Global NC and domain average demographically-corrected t-scores were generated. There were no significant differences between Younger (<50 years) Latina/os and non-Hispanic Whites on Global NC function or NC domains (all p's >.10), with generally small effect sizes. Older Latina/os (≥50 years) were significantly more impaired than Older Non-Hispanic Whites on processing speed and learning, with trends in Global NC function and memory. Further, effect sizes fell within the medium to large range (Cohen's d's = .49-1.15). This study suggests that older Latina/os are at potentially greater risk for NC impairment, particularly in processing speed and learning, when compared to similarly-aged non-Hispanic whites.

Crystal structure of a junction between two Z-DNA helices.

The double helix of DNA, when composed of dinucleotide purine-pyrimidine repeats, can adopt a left-handed helical structure called Z-DNA. For reasons not entirely understood, such dinucleotide repeats in genomic sequences have been associated with genomic instability leading to cancer. Adoption of the left-handed conformation results in the formation of conformational junctions: A B-to-Z junction is formed at the boundaries of the helix, whereas a Z-to-Z junction is commonly formed in sequences where the dinucleotide repeat is interrupted by single base insertions or deletions that bring neighboring helices out of phase. B-Z junctions are shown to result in exposed nucleotides vulnerable to chemical or enzymatic modification. Here we describe the three-dimensional structure of a Z-Z junction stabilized by Zalpha, the Z-DNA binding domain of the RNA editing enzyme ADAR1. We show that the junction structure consists of a single base pair and leads to partial or full disruption of the helical stacking. The junction region allows intercalating agents to insert themselves into the left-handed helix, which is otherwise resistant to intercalation. However, unlike a B-Z junction, in this structure the bases are not fully extruded, and the stacking between the two left-handed helices is not continuous.

Advancing earlier transdiagnostic identification of mental health risk: A pragmatic approach at the transition to toddlerhood.

OBJECTIVES: In light of the youth mental health crisis, as 1 in 5 children have a mental disorder diagnosis by age 3, identification of transdiagnostic behavioral vulnerability prior to impairing psychopathology must occur at an earlier phase of the clinical sequence. Here, we lay the groundwork for a pragmatic irritability measure to identify at-risk infant-toddlers. METHODS: Data comprised N = 350 diverse infant-toddlers and their mothers assessed at ∼14 months old for irritability (Multidimensional Assessment Profiles- Temper Loss-Infant/Toddler (MAPS-TL-IT) and impairment (Early Childhood Irritability-Related Impairment Interview, E-CRI; and Family Life Impairment Scale (FLIS). Bimonthly follow-up surveys assessed impairment (FLIS) over the following year. RESULTS: Stepwise logistic regression indicated that 5 MAPS-TL-IT items were most informative for differentiating concurrent impairment on the FLIS: "frustrated about small things"; "hit, bite, or kick during tantrums"; "trouble cheering up when grumpy"; "grumpy during fun activities" and "tantrums in public". With this summed score, Receiver Operating Characteristics analysis differentiating concurrent impairment on the E-CRI indicated good classification accuracy for (Area under the curve = 0.755, p < 0.05), with a cutoff of 5 maximizing sensitivity (71.4%) and specificity (70.6%). Elevated irritability on this MAPS-TL-IT clinically optimized screener increased likelihood of persistently elevated FLIS impairment trajectories over the following year more than fourfold (OR = 4.37; Confidence intervals = 2.40-7.97, p < 0.001). CONCLUSIONS: Our findings represent the first step toward a pragmatic tool for screening for transdiagnostic mental health risk in toddlers, optimized for feasibility in clinical care. This has potential to strengthen resilience pathways via earlier identification of mental health risk and corollary prevention in toddlers.

Prevalence, stability, and predictive utility of the Multidimensional Assessment of Preschoolers Scales clinically optimized irritability score: Pragmatic early assessment of mental disorder risk.

OBJECTIVES: Characterizing the scope and import of early childhood irritability is essential for real-world actualization of this reliable indicator of transdiagnostic mental health risk. Thus, we utilize pragmatic assessment to establish prevalence, stability, and predictive utility of clinically significant early childhood irritability. METHODS: Data included two independent, diverse community samples of preschool age children (N = 1857; N = 1490), with a subset enriched for risk (N = 425) assessed longitudinally from early childhood through preadolescence (∼4-9 years old). A validated, brief (2-item) scale pragmatically assessed clinically significant irritability. In the longitudinal subsample, clinical interviews assessed internalizing/externalizing disorders. RESULTS: One in five preschool-age children had clinically significant irritability, which was independently replicated. Irritability was highly stable through preadolescence. Children with versus without clinically significant early childhood irritability had greater odds of early onset, persistent internalizing/externalizing disorders. The pragmatic assessment effectively screened out low-risk children and identified 2/3 of children with early-onset, persistent psychopathology. CONCLUSIONS: Clinically significant early childhood irritability prevalence is akin to the pediatric obesity epidemic and may warrant similar universal screening/intervention. Also, irritability's stability demonstrates the common guidance "they'll grow out of it" to be false. Finally, pragmatic irritability assessment has transdiagnostic predictive power and addresses a need for feasible measures to flag risk.

Neurocognitive, Sociocultural, and Psychological Factors Impacting Medication Beliefs Among HIV-Seropositive Latinx Adults.

Among Latinx people living with HIV (PLWH), neurocognitive (NC) function, culture, and mental health impact medication adherence. Similarly, health beliefs and attitudes play a role in health care barriers and health behaviors. Research has not examined the effect that compromised neurocognition, sociocultural factors, and mental health have on health beliefs and attitudes. This is especially relevant for Latinx PLWH who are disproportionately impacted by HIV, given that sociocultural factors may uniquely impact HIV-related NC and psychological sequelae. This study investigated the associations between neurocognition, sociocultural factors, mental health, health beliefs, and health attitudes among Latinx HIV-seropositive adults. Within a sample of 100 Latinx PLWH, better verbal learning and executive functioning abilities were associated with more positive attitudes about the benefits of medications and memory for medications. In terms of sociocultural factors, higher English language competence was related to better self-reported memory for medications, and overall, higher US acculturation was associated with more positive attitudes toward health professionals. Depressive symptomatology was negatively associated with attitudes toward medications and health professionals, as well as with self-reported memory for medications. These findings highlight the important interplay between NC, sociocultural, psychological factors, and health beliefs among Latinx PLWH. Adherence intervention strategies and suggestions for dispensing medical information are presented for clinicians and health care practitioners.

Migrating monocytes recruited to the spleen play an important role in control of blood stage malaria.

Host responses controlling blood-stage malaria include both innate and acquired immune effector mechanisms. During Plasmodium chabaudi infection in mice, a population of CD11b(high)Ly6C(+) monocytes are generated in bone marrow, most of which depend on the chemokine receptor CCR2 for migration from bone marrow to the spleen. In the absence of this receptor mice harbor higher parasitemias. Most importantly, splenic CD11b(high)Ly6C(+) cells from P chabaudi-infected wild-type mice significantly reduce acute-stage parasitemia in CCR2(-/-) mice. The CD11b(high)Ly6C(+) cells in this malaria infection display effector functions such as production of inducible nitric oxide synthase and reactive oxygen intermediates, and phagocytose P chabaudi parasites in vitro, and in a proportion of the cells, in vivo in the spleen, suggesting possible mechanisms of parasite killing. In contrast to monocyte-derived dendritic cells, CD11b(high)Ly6C(+) cells isolated from malaria-infected mice express low levels of major histocompatibility complex II and have limited ability to present the P chabaudi antigen, merozoite surface protein-1, to specific T-cell receptor transgenic CD4 T cells and fail to activate these T cells. We propose that these monocytes, which are rapidly produced in the bone marrow as part of the early defense mechanism against invading pathogens, are important for controlling blood-stage malaria parasites.

Poststeroid panniculitis in an adult.

Poststeroid panniculitis is a rare disorder usually reported in children after a sudden decrease or withdrawal of corticosteroid therapy. We report a case in an adult, a finding very rarely reported in English literature. The case report is about a 34-year-old man with multiple erythematous, firm and tender subcutaneous nodules on both thighs and legs after the withdrawal of long-term doses of dexamethasone prescribed before and after surgery for a frontoinsular anaplastic oligodendroglioma. Histopathologic study revealed mainly lobular and also septal panniculitis with fat necrosis and characteristic needle-shaped clefts in radial arrangement within fat cells and multinucleated giant cells. The lesions resolved in about 5 months, after weight loss and application of topical corticosteroids for 1 month, leaving only residual hyperpigmentation.

Gradual decline in malaria-specific memory T cell responses leads to failure to maintain long-term protective immunity to Plasmodium chabaudi AS despite persistence of B cell memory and circulating antibody.

The mechanisms responsible for the generation and maintenance of immunological memory to Plasmodium are poorly understood and the reasons why protective immunity in humans is so difficult to achieve and rapidly lost remain a matter for debate. A possible explanation for the difficulty in building up an efficient immune response against this parasite is the massive T cell apoptosis resulting from exposure to high-dose parasite Ag. To determine the immunological mechanisms required for long-term protection against P. chabaudi malaria and the consequences of high and low acute phase parasite loads for acquisition of protective immunity, we performed a detailed analysis of T and B cell compartments over a period of 200 days following untreated and drug-treated infections in female C57BL/6 mice. By comparing several immunological parameters with the capacity to control a secondary parasite challenge, we concluded that loss of full protective immunity is not determined by acute phase parasite load nor by serum levels of specific IgG2a and IgG1 Abs, but appears to be a consequence of the progressive decline in memory T cell response to parasites, which occurs similarly in untreated and drug-treated mice with time after infection. Furthermore, by analyzing adoptive transfer experiments, we confirmed the major role of CD4(+) T cells for guaranteeing long-term full protection against P. chabaudi malaria.

Survey of 138 Conjunctival Tumors in the Dominican Republic.

PURPOSE: To report the frequency of conjunctival tumors in the Dominican Republic. METHODS: Retrospective noninterventional case series. One hundred thirty-eight consecutive patients with a conjunctival mass evaluated at two tertiary referral centers from 2010 to 2018. Main outcome measures were frequency of tumors by diagnosis and distribution of tumors relative to patients' age and gender. RESULTS: The mean age at presentation was 41.2 years (median, 42 years; range 10 days - 91 years). There were 83 male patients (60%) and 55 female patients (40%). The three most common specific diagnoses were junctional, compound, and subepithelial naevi (47 [34%]), squamous cell carcinoma (SCC) (26 [19%]) and conjunctival squamous intraepithelial neoplasia (CIN) (17 [12%]). The mean age at detection was 36.5 years for non-malignant tumors and 56.3 years for malignant tumors (p < .001), with a mean difference of 19.8 years at time of diagnosis (95% CI, 10.7-28.8). Benign tumors were more common in children and young adults; malignant and premalignant tumors were more common in mid and older adults (p = .009). Malignant tumors were more common in males (73%) than in females (27%) (p = .04). CONCLUSION: In the Dominican Republic, conjunctival tumors are benign (63%), premalignant (13%) and malignant (24%). Malignant tumors are more common in older adults and men.

Neurocognitive intra-individual variability within HIV+ adults with and without current substance use.

OBJECTIVE: HIV infection and current substance use (SU) are linked to cognitive and functional deficits, yet findings on their combined effects are mixed. Neurocognitive intraindividual variability, measured as dispersion of scores across a neuropsychological battery, is associated with worse cognitive outcomes and functional deficits among HIV+ adults but has not been studied in the context of HIV+ adults with current SU. We hypothesized that, among HIV+ adults, current SU would be associated with greater dispersion, that greater dispersion would be associated with worse medication adherence, and that this relationship would be worse among substance users. METHOD: Forty HIV+ adults completed neuropsychological, psychiatric, SU, and medical evaluations and an electronic medication adherence measure. General linear models evaluated the main effect of SU status on neurocognitive dispersion, and models stratified by SU status evaluated the effect of dispersion on medication adherence, adjusting for relevant covariates. RESULTS: The SU+ group showed greater dispersion than did the SU- group, t(38) = 2.74, p = .049, d = 0.81, but this association did not survive multiple comparisons. Stratified analyses indicated a negative relationship between dispersion and medication adherence among the SU+ group but not in the SU- group; however, this effect was reduced after accounting for depressive symptoms. CONCLUSIONS: We found preliminary evidence that current SU is associated with greater neurocognitive dispersion among HIV+ adults. SU and neurocognitive dispersion may have a synergistic effect on medication adherence; however, this effect is largely accounted for by depressive symptoms. Future research should examine progression of dispersion in HIV and consequent neurocognitive and functional deficits in those with current SU. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Physical Activity, Exercise, and Physiotherapy in Parkinson's Disease: Defining the Concepts.

BACKGROUND: Exercise is gaining extreme relevancy as a new therapeutic intervention for Parkinson's disease (PD). However, the frequent misuse of the concepts exercise, physiotherapy, and physical activity limits the possibility of summarizing research findings. This review aims to clarify these concepts and summarize the evidence on exercise in PD. METHODS: We critically appraised physical activity-related concepts and conducted a systematic review of clinical trials evaluating exercise interventions in PD. Additionally, we discussed the implications for PD clinical practice and research. RESULTS: Exercise is a subset of physical activity, and a major component of physiotherapy for PD management, having as the main goal to improve physical fitness. The appraisal of the 83 identified clinical trials found high variability in exercise interventions. Multimodal exercise was the most studied, and 60 minutes, two times/week for 12 weeks, the most reported prescription parameters. CONCLUSION: The best available evidence recommends increasing physical activity levels in PD. Exercise and physiotherapy programs seem the most efficacious strategies to achieve this goal. As a result of the heterogeneity in the type and manner exercise is prescribed, it is not possible to propose strong recommendations for exercise in PD. We believe that, in addition to the clarification of concepts here presented, a collaborative and rigorous work of different areas of knowledge is needed.

Cryo-EM structure of arabinosyltransferase EmbB from Mycobacterium smegmatis.

Arabinosyltransferase B (EmbB) belongs to a family of membrane-bound glycosyltransferases that build the lipidated polysaccharides of the mycobacterial cell envelope, and are targets of anti-tuberculosis drug ethambutol. We present the 3.3 Å resolution single-particle cryo-electron microscopy structure of Mycobacterium smegmatis EmbB, providing insights on substrate binding and reaction mechanism. Mutations that confer ethambutol resistance map mostly around the putative active site, suggesting this to be the location of drug binding.