Lack of authentic atrial fibrillation in commonly used murine atrial fibrillation models.

The mouse is a useful preclinical species for evaluating disease etiology due to the availability of a wide variety of genetically modified strains and the ability to perform disease-modifying manipulations. In order to establish an atrial filtration (AF) model in our laboratory, we profiled several commonly used murine AF models. We initially evaluated a pharmacological model of acute carbachol (CCh) treatment plus atrial burst pacing in C57BL/6 mice. In an effort to observe micro-reentrant circuits indicative of authentic AF, we employed optical mapping imaging in isolated mouse hearts. While CCh reduced atrial refractoriness and increased atrial tachyarrhythmia vulnerability, the left atrial (LA) excitation patterns were rather regular without reentrant circuits or wavelets. Therefore, the atrial tachyarrhythmia resembled high frequency atrial flutter, not typical AF per se. We next examined both a chronic angiotensin II (Ang II) infusion model and the surgical model of transverse aortic constriction (TAC), which have both been reported to induce atrial and ventricular structural changes that serve as a substrates for micro-reentrant AF. Although we observed some extent of atrial remodeling such as fibrosis or enlarged LA diameter, burst pacing-induced atrial tachyarrhythmia vulnerability did not differ from control mice in either model. This again suggested that an AF-like pathophysiology is difficult to demonstrate in the mouse. To continue searching for a valid murine AF model, we studied mice with a cardiac-specific deficiency (KO) in liver kinase B1 (Cardiac-LKB1), which has been reported to exhibit spontaneous AF. Indeed, the electrocardiograms (ECG) of conscious Cardiac-LKB1 KO mice exhibited no P waves and had irregular RR intervals, which are characteristics of AF. Histological evaluation of Cardiac-LKB1 KO mice revealed dilated and fibrotic atria, again consistent with AF. However, atrial electrograms and optical mapping revealed that electrical activity was limited to the sino-atrial node area with no electrical conduction into the atrial myocardium beyond. Thus, Cardiac-LKB1 KO mice have severe atrial myopathy or atrial standstill, but not AF. In summary, the atrial tachyarrhythmias we observed in the four murine models were distinct from typical human AF, which often exhibits micro- or macro-reentrant atrial circuits. Our results suggest that the four murine AF models we examined may not reflect human AF well, and raise a cautionary note for use of those murine models to study AF.

Imidazo[1,5-a]quinoxalines as irreversible BTK inhibitors for the treatment of rheumatoid arthritis.

Imidazo[1,5-a]quinoxalines were synthesized that function as irreversible Bruton's tyrosine kinase (BTK) inhibitors. The syntheses and SAR of this series of compounds are presented as well as the X-ray crystal structure of the lead compound 36 in complex with a gate-keeper variant of ITK enzyme. The lead compound showed good in vivo efficacy in preclinical RA models.

Selective functional inhibition of JAK-3 is sufficient for efficacy in collagen-induced arthritis in mice.

OBJECTIVE: All gamma-chain cytokines signal through JAK-3 and JAK-1 acting in tandem. We undertook this study to determine whether the JAK-3 selective inhibitor WYE-151650 would be sufficient to disrupt cytokine signaling and to ameliorate autoimmune disease pathology without inhibiting other pathways mediated by JAK-1, JAK-2, and Tyk-2. METHODS: JAK-3 kinase selective compounds were characterized by kinase assay and JAK-3-dependent (interleukin-2 [IL-2]) and -independent (IL-6, granulocyte-macrophage colony-stimulating factor [GM-CSF]) cell-based assays measuring proliferation or STAT phosphorylation. In vivo, off-target signaling was measured by IL-22- and erythropoietin (EPO)-mediated models, while on-target signaling was measured by IL-2-mediated signaling. Efficacy of JAK-3 inhibitors was determined using delayed-type hypersensitivity (DTH) and collagen-induced arthritis (CIA) models in mice. RESULTS: In vitro, WYE-151650 potently suppressed IL-2-induced STAT-5 phosphorylation and cell proliferation, while exhibiting 10-29-fold less activity against JAK-3-independent IL-6- or GM-CSF-induced STAT phosphorylation. Ex vivo, WYE-151650 suppressed IL-2-induced STAT phosphorylation, but not IL-6-induced STAT phosphorylation, as measured in whole blood. In vivo, WYE-151650 inhibited JAK-3-mediated IL-2-induced interferon-gamma production and decreased the natural killer cell population in mice, while not affecting IL-22-induced serum amyloid A production or EPO-induced reticulocytosis. WYE-151650 was efficacious in mouse DTH and CIA models. CONCLUSION: In vitro, ex vivo, and in vivo assays demonstrate that WYE-151650 is efficacious in mouse CIA despite JAK-3 selectivity. These data question the need to broadly inhibit JAK-1-, JAK-2-, or Tyk-2-dependent cytokine pathways for efficacy.

A meta-analysis of voucher-based reinforcement therapy for substance use disorders.

AIMS: To systematically investigate the effectiveness of voucher-based reinforcement therapy for the treatment of substance use disorders. METHODS: Effect sizes and 95% confidence intervals were calculated for studies published between January 1991 and March 2004 that utilized voucher-based reinforcement therapy (VBRT) or related monetary-based incentives to treat substance use disorders (SUDs). FINDINGS: Thirty studies involved interventions targeting abstinence from drug use using experimental designs where effects on treatment outcome could be attributed to the VBRT intervention. The estimated average effect size (r) for those studies was 0.32 (95% CI 0.26-0.38). Analyses of variables thought to moderate VBRT effect sizes revealed that more immediate voucher delivery and greater monetary value of the voucher were associated with larger effect sizes. Additional studies were identified wherein VBRT was used to target clinic attendance (n = 6) or medication compliance (n = 4). VBRT studies targeting attendance produced average effect sizes of 0.15 (95% CI 0.02-0.28), while those that targeted medication compliance produced an average effect of 0.32 (95% CI 0.15-0.47). No significant moderators were identified for these 10 studies. CONCLUSIONS: Overall, VBRT generated significantly better outcomes than did control treatments. These results further support the efficacy of VBRT, quantify the magnitude of its effects, identify significant moderators and suggest potential directions for future research.

Influence of the duration of abstinence on the relative reinforcing effects of cigarette smoking.

RATIONALE: Sustaining smoking abstinence during the initial weeks of a cessation effort is highly correlated with long-term smoking abstinence. However, experimental research is needed to establish a direct causal relationship between achieving early abstinence and lowered relapse risk. OBJECTIVE: In the present study, we tested whether a period of sustained abstinence directly decreases the relative reinforcing effects of cigarette smoking. METHODS: Participants were 63 adult smokers who were randomized into one of three conditions: 14-day (14C), 7-day (7C), and 1-day (1C) contingent payment for smoking abstinence. Smoking status was assessed three times per day for 14 consecutive days using breath carbon monoxide monitoring and an abstinence criterion of < or = 4 ppm. In the 14C condition, monetary payment was contingent on abstinence for all 14 days; in the 7C condition, payment was noncontingent for days 1-7 and contingent for days 8-14; in the 1C condition, payment was noncontingent for days 1-13 and contingent for day 14. On day 14, all participants completed a 3-h preference session under controlled laboratory conditions wherein they could make a maximum of 20 exclusive choices between options to smoke (two puffs/choice) or earn money (0.25 dollars/choice). Preference was deemed an index of the relative reinforcing effects of smoking and money. RESULTS: A significantly lower proportion of participants in the 14C condition ever chose the smoking option (19%) compared to those in the 7C (57%) or 1C (62%) conditions. CONCLUSIONS: These results provide experimental evidence that sustained abstinence can decrease the relative reinforcing effects of smoking, an effect that may be related to the commonly observed decrease in relapse risk among those who are able to sustain smoking abstinence during the initial weeks of a cessation effort.

Environmental enrichment for the captive spectacled bear (Tremarctos ornatus).

As part a series of investigations of environmental enrichment methods for zoo animals, two spectacled bears (Tremarctos ornatus) were observed for 40 h, documenting use of cage space and behaviors, using a detailed ethogram. Baseline data showed concentration of activity into limited areas of the enclosure and expression of a relatively restricted subset of the species' behavioral repertoire. Introduction of a climbing structure resulted in increased behavioral diversity, both in the use of the enclosure's physical space and the behaviors displayed in various parts of the enclosure.

PI3K-δ and PI3K-γ inhibition by IPI-145 abrogates immune responses and suppresses activity in autoimmune and inflammatory disease models.

Phosphoinositide-3 kinase (PI3K)-δ and PI3K-γ are preferentially expressed in immune cells, and inhibitors targeting these isoforms are hypothesized to have anti-inflammatory activity by affecting the adaptive and innate immune response. We report on a potent oral PI3K-δ and PI3K-γ inhibitor (IPI-145) and characterize this compound in biochemical, cellular, and in vivo assays. These studies demonstrate that IPI-145 exerts profound effects on adaptive and innate immunity by inhibiting B and T cell proliferation, blocking neutrophil migration, and inhibiting basophil activation. We explored the therapeutic value of combined PI3K-δ and PI3K-γ blockade, and IPI-145 showed potent activity in collagen-induced arthritis, ovalbumin-induced asthma, and systemic lupus erythematosus rodent models. These findings support the hypothesis that inhibition of immune function can be achieved through PI3K-δ and PI3K-γ blockade, potentially leading to significant therapeutic effects in multiple inflammatory, autoimmune, and hematologic diseases.

Clinical implications of reinforcement as a determinant of substance use disorders.

Extensive scientific evidence indicates that reinforcement plays an important role in the genesis, maintenance, and recovery from substance use disorders. In this chapter, we review recent clinical research from laboratory, clinic, and naturalistic settings examining the role of reinforcement in substance use disorders. Well-controlled human laboratory studies are reviewed characterizing orderly interactions between the reinforcing effects of drugs and environmental context that have important implications for understanding risk factors for substance use disorders and for the development of efficacious interventions. Recent treatment-outcome studies on voucher-based contingency management and community reinforcement therapy are reviewed demonstrating how reinforcement and related principles can be used to improve outcomes across a wide range of different substance use disorders and populations. Overall, the chapter characterizes a vigorous area of clinical research that has much to contribute to a scientific analysis of substance use disorders.

An experimental test of the influence of prior cigarette smoking abstinence on future abstinence.

Significant positive associations between early and later abstinence are often reported in clinical trials on smoking cessation, but those relationships do not permit causal inferences. The present study was conducted to examine experimentally whether prior smoking abstinence histories can directly facilitate later abstinence, using a contingency management procedure to manipulate prior abstinence. A total of 40 adult cigarette smokers who were not trying to quit were randomly assigned to one of two conditions: Contingent ALL (C-ALL), who earned monetary incentives contingent on smoking abstinence during three 5 day experimental periods; or Contingent LAST (C-LAST), who earned incentives independent of abstinence during the first two periods (i.e., noncontingent payments) and contingent on abstinence during the final period. The contingency management procedure was effective in establishing different abstinence histories in the two conditions during the first two periods. Comparison of abstinence levels between the C-ALL and C-LAST conditions during the third period showed significantly greater abstinence in the C-ALL condition, although nicotine withdrawal and other subject ratings generally did not differ significantly between the two conditions. These results provide experimental evidence that prior abstinence histories can directly influence subsequent efforts to abstain from smoking.

A pilot study on voucher-based incentives to promote abstinence from cigarette smoking during pregnancy and postpartum.

We report results from a pilot study examining the use of vouchers redeemable for retail items as incentives for smoking cessation during pregnancy and postpartum. Of 100 study-eligible women who were still smoking upon entering prenatal care, 58 were recruited from university-based and community obstetric practices to participate in a smoking cessation study. Participants were assigned to either contingent or noncontingent voucher conditions. Vouchers were available during pregnancy and for 12 weeks postpartum. In the contingent condition, vouchers were earned for biochemically verified smoking abstinence. In the noncontingent condition, vouchers were earned independent of smoking status. Abstinence monitoring and associated voucher delivery was conducted daily during the initial 5 days of the cessation effort, gradually decreased to every other week antepartum, increased to once weekly during the initial 4 weeks postpartum, and then decreased again to every other week for the remaining 8 weeks of the postpartum intervention period. Contingent vouchers increased 7-day point-prevalence abstinence at the end-of-pregnancy (37% vs. 9%) and 12-week postpartum (33% vs. 0%) assessments. That effect was sustained through the 24-week postpartum assessment (27% vs. 0%), which was 12 weeks after discontinuation of the voucher program. Total mean voucher earnings across antepartum and postpartum were 397 US dollars (SD=414 US dollars) and 313 US dollars (SD=142 dollars) in the contingent and noncontingent conditions, respectively. The magnitude of these treatment effects exceed levels typically observed with pregnant and recently postpartum smokers, and the maintenance of effects through 24 weeks postpartum extends the duration beyond those reported previously.