Promoting Smoke-Free Homes: A Novel Behavioral Intervention Using Real-Time Audio-Visual Feedback on Airborne Particle Levels

Interventions are needed to protect the health of children who live with smokers. We pilot-tested a real-time intervention for promoting behavior change in homes that reduces second hand tobacco smoke (SHS) levels. The intervention uses a monitor and feedback system to provide immediate auditory and visual signals triggered at defined thresholds of fine particle concentration. Dynamic graphs of real-time particle levels are also shown on a computer screen. We experimentally evaluated the system, field-tested it in homes with smokers, and conducted focus groups to obtain general opinions. Laboratory tests of the monitor demonstrated SHS sensitivity, stability, precision equivalent to at least 1 µg/m³, and low noise. A linear relationship (R² = 0.98) was observed between the monitor and average SHS mass concentrations up to 150 µg/m³. Focus groups and interviews with intervention participants showed in-home use to be acceptable and feasible. The intervention was evaluated in 3 homes with combined baseline and intervention periods lasting 9 to 15 full days. Two families modified their behavior by opening windows or doors, smoking outdoors, or smoking less. We observed evidence of lower SHS levels in these homes. The remaining household voiced reluctance to changing their smoking activity and did not exhibit lower SHS levels in main smoking areas or clear behavior change; however, family members expressed receptivity to smoking outdoors. This study established the feasibility of the real-time intervention, laying the groundwork for controlled trials with larger sample sizes. Visual and auditory cues may prompt family members to take immediate action to reduce SHS levels. Dynamic graphs of SHS levels may help families make decisions about specific mitigation approaches.     

Production of multimeric forms of CD4 through a sugar-based cross-linking strategy

We have developed a three-step cross-linking procedure that is specifically targeted at the carbohydrate on a protein and applied it to CD4 as a model system for studying the role of multivalent interactions in function. In the first step CD4 was oxidized with periodate, creating aldehydes that served as targets for the subsequent chemistry. Next the aldehydes were modified with cystamine, converting the reactive group into a thiol. Finally cross-linking through the thiol moiety was generated with the homobifunctional cross-linker bismaleimidohexane. With this procedure, approximately 60% of the CD4 was converted into higher molecular weight complexes that were soluble and retained function as assessed by glycoprotein gp120 binding activity. CD4 dimers and tetramers by mass were 4 and 15 times as active as CD4 monomer in blocking virus infection with HTLV-IIIB in an in vitro cellular assay. The cross-linking chemistry provides an efficient method for producing homomultimers of a glycoprotein.     

Plasma FA composition in familial LCAT deficiency indicates SOAT2-derived cholesteryl ester formation in humans

Mutations in the LCAT gene cause familial LCAT deficiency (Online Mendelian Inheritance in Man ID: #245900), a very rare metabolic disorder. LCAT is the only enzyme able to esterify cholesterol in plasma, whereas sterol O-acyltransferases 1 and 2 are the enzymes esterifying cellular cholesterol in cells. Despite the complete lack of LCAT activity, patients with familial LCAT deficiency exhibit circulating cholesteryl esters (CEs) in apoB-containing lipoproteins. To analyze the origin of these CEs, we investigated 24 carriers of LCAT deficiency in this observational study. We found that CE plasma levels were significantly reduced and highly variable among carriers of two mutant LCAT alleles (22.5 [4.0–37.8] mg/dl) and slightly reduced in heterozygotes (218 [153–234] mg/dl). FA distribution in CE (CEFA) was evaluated in whole plasma and VLDL in a subgroup of the enrolled subjects. We found enrichment of C16:0, C18:0, and C18:1 species and a depletion in C18:2 and C20:4 species in the plasma of carriers of two mutant LCAT alleles. No changes were observed in heterozygotes. Furthermore, plasma triglyceride-FA distribution was remarkably similar between carriers of LCAT deficiency and controls. CEFA distribution in VLDL essentially recapitulated that of plasma, being mainly enriched in C16:0 and C18:1, while depleted in C18:2 and C20:4. Finally, after fat loading, chylomicrons of carriers of two mutant LCAT alleles showed CEs containing mainly saturated FAs. This study of CEFA composition in a large cohort of carriers of LCAT deficiency shows that in the absence of LCAT-derived CEs, CEs present in apoB-containing lipoproteins are derived from hepatic and intestinal sterol O-acyltransferase 2.     

The value of decreasing the duration of the infectious period of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection

Finding medications or vaccines that may decrease the infectious period of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could potentially reduce transmission in the broader population. We developed a computational model of the U.S. simulating the spread of SARS-CoV-2 and the potential clinical and economic impact of reducing the infectious period duration. Simulation experiments found that reducing the average infectious period duration could avert a median of 442,852 [treating 25% of symptomatic cases, reducing by 0.5 days, reproductive number (R₀) 3.5, and starting treatment when 15% of the population has been exposed] to 44.4 million SARS-CoV-2 cases (treating 75% of all infected cases, reducing by 3.5 days, R₀ 2.0). With R₀ 2.5, reducing the average infectious period duration by 0.5 days for 25% of symptomatic cases averted 1.4 million cases and 99,398 hospitalizations; increasing to 75% of symptomatic cases averted 2.8 million cases. At $500/person, treating 25% of symptomatic cases saved $209.5 billion (societal perspective). Further reducing the average infectious period duration by 3.5 days averted 7.4 million cases (treating 25% of symptomatic cases). Expanding treatment to 75% of all infected cases, including asymptomatic infections (R₀ 2.5), averted 35.9 million cases and 4 million hospitalizations, saving $48.8 billion (societal perspective and starting treatment after 5% of the population has been exposed). Our study quantifies the potential effects of reducing the SARS-CoV-2 infectious period duration.     

Transforming growth factor beta induces the production of interleukin 6 by human peripheral blood mononuclear cells

Previous studies have indicated that the cytokine transforming growth factor beta 1 (TGF beta 1) has immunosuppressive properties and can inhibit the production of tumor necrosis factor (TNF) and Interleukin 1 (IL 1) by human peripheral blood mononuclear cells. In this study, we have examined the effects of TGF beta 1 on the production of Interleukin 6 (IL 6) by human peripheral blood mononuclear cells. Treatment with only TGF beta 1 leads to the induction of IL 6, and this was both dose- and time-dependent. The effect of TGF beta 1 was evident at the level of IL 6 mRNA, suggesting TGF beta 1-induced de novo synthesis of IL 6. Induction of IL 6 by TGF beta 1 was specific, as other cytokines made by mononuclear cells (TNF and IL 1) were not induced by TGF beta 1. Furthermore, when a panel of stimuli were compared for their ability to induce IL 1, TNF and IL 6 in the presence or absence of TGF beta 1, IL 6 levels were augmented in the presence of TGF beta 1, while the induction of IL 1 and TNF was inhibited significantly. These results indicate that TGF beta 1 has complex effects on the production of cytokines by peripheral blood mononuclear cells and that TGF beta 1 is not inhibitory for all cytokine production. The ability of TGF beta 1 to induce IL 6 suggests that IL 6 may mediate some of the effects of TGF beta 1.     

Activation of AMPK by Bitter Melon Triterpenoids Involves CaMKKβ

We recently showed that bitter melon-derived triterpenoids (BMTs) activate AMPK and increase GLUT4 translocation to the plasma membrane in vitro, and improve glucose disposal in insulin resistant models in vivo. Here we interrogated the mechanism by which these novel compounds activate AMPK, a leading anti-diabetic drug target. BMTs did not activate AMPK directly in an allosteric manner as AMP or the Abbott compound (A-769662) does, nor did they activate AMPK by inhibiting cellular respiration like many commonly used anti-diabetic medications. BMTs increased AMPK activity in both L6 myotubes and LKB1-deficient HeLa cells by 20–35%. Incubation with the CaMKKβ inhibitor, STO-609, completely attenuated this effect suggesting a key role for CaMKKβ in this activation. Incubation of L6 myotubes with the calcium chelator EGTA-AM did not alter this activation suggesting that the BMT-dependent activation was Ca²⁺-independent. We therefore propose that CaMKKβ is a key upstream kinase for BMT-induced activation of AMPK.     

The XcpR protein of Pseudomonas aeruginosa dimerizes via its N-terminus

Extracellular protein secretion by the main terminal branch of the general secretory pathway in Pseudomonas aeruginosa requires a secretion machinery comprising the products of at least 12 genes. One of the components of this machinery, the XcpR protein, belongs to a large family of related proteins distinguished by the presence of a highly conserved nucleotide binding domain (Walker box A). The XcpR protein is essential for the process of extracellular secretion and amino acid substitutions within the Walker A sequence result in inactive XcpR. The same mutations exert a dominant negative effect on protein secretion when expressed in wild-type bacteria. Transdominance of XcpR mutants suggests that this protein is involved in interactions with other components of the secretion machinery or that it functions as a multimer. In this study, the amino-terminal portion of the cI repressor protein of phage λ was used as a reporter of dimerization in Escherichia coli following fusion to full-length as well as a truncated form of XcpR. The cI–XcpR hybrid proteins were able to dimerize, as demonstrated by the immunity of bacteria expressing them to killing by λ phage. The full-length XcpR as well as several deletion mutants of XcpR were able to disrupt the dimerization of the chimeric cI–XcpR protein. The disruption of cI–XcpR dimers using the deletion mutants of XcpR, combined with the analysis of their dominant negative effects on protein secretion, was used to map the minimal dimerization domain of XcpR, which is located within an 85 amino acid region in its N-terminal domain. Taken together, the data presented in this paper suggest that the XcpR protein dimerizes via its N-terminus and that this dimerization is essential for extracellular protein secretion.