Genotoxicity and mutagenicity induced by acute crack cocaine exposure in mice

Context: Crack cocaine is an illicit drug derived from cocaine, in which use and abuse have increased around the world, especially in developing countries. Objectives: The aim of this study was to evaluate genomic damage in multiple organs of mice following acute exposure to crack cocaine. For this purpose, single cell gel (comet) assay in peripheral blood, liver, kidney, and brain cells was performed and micronucleus test for bone narrow and liver cells was also made in this setting. Material and methods: A total of 20 C57BL/10 male mice were distributed into four groups, as follows: 0, 4.5, 9, and 18?mg/kg b.w. of crack cocaine dissolved to 1% dimethyl sulfoxide by intraperitoneal (i.p.) route. All animals were sacrificed 24?h after i.p. injection. Results: The results showed that crack cocaine induced DNA damage in peripheral blood, and brain cells for higher doses used as depicted by single cell gel (comet) assay data. Analysis of kidney cells showed no genetic damage for all groups tested. The number of micronucleated cells did not increase after crack cocaine exposure in bone narrow or liver cells. Conclusion: In summary, crack cocaine is a genotoxic agent in peripheral blood, liver, and brain cells but not mutagenic in multiple organs of mice.     

Outcomes related to variation in hospital pulmonary embolus observation stay utilization

Objectives: To characterize hospital variation in use of observation stays to manage pulmonary embolism (PE) and its association with subsequent outcomes.

Methods: We performed a cross-sectional study of hospitals reporting ≥75 PE encounters (emergency department, observation stay or inpatient admission) using Premier data from 11/2012-3/2015. We included hospital encounters for adults with a primary diagnosis of PE (415.1x), ≥1 diagnostic test claim for PE on day 0-2 and evidence of PE treatment. Hospitals were divided into tertiles (Ts) based on the proportion of all PE encounters managed as an observation stay. The association between observation stay utilization and the proportion of PE encounters resulting in in-hospital death or re-admission within the same or subsequent 2-months were compared across Ts using a generalized estimating equation adjusted for individual encounter disease severity.

Results: Observation PE management increased over the study period (1.9%-5.4%; Pearson’s r = 0.88, p < 0.001). Of all hospitals reporting ≥1 PE encounter, 255 had ≥75 encounters (representing a total of 38,172 PE encounters) and were included in the analysis. Individual hospital observation use for PE management varied from 0%-33.9%. Mean hospital rates of PE observation stay by T were T1 = 0.1%, T2 = 2.2% and T3 = 7.9%. Hospitals that used observation stays most frequently (T3) were more likely in the South or Mid-west (p < 0.001), to be a teaching hospital (p = 0.03) and less likely to serve an urban population (p = 0.02). Hospitals in T3 (n = 11,780 encounters) were not associated with a statistically significant increased risk of in-hospital death (2.3% vs. 2.1%-2.6%) or all-cause (4.7% vs. 5.1%-5.4%), venous thromboembolism-(1.4% vs. 1.8%-2.0%) or major bleeding (0.3% vs. 0.2-0.3%)-related re-admission in the same or subsequent 2-months compared to T1 (n = 12,940 encounters) and T2 (n = 13,452 encounters).

Conclusion: PE management via observation stays has increased over recent years. Hospitals more frequently utilizing observation stays may not experience increased negative outcomes, such as re-admission.     

Disparities in Access to Easy-to-Use Services for Children with Special Health Care Needs

Objectives Families, clinicians and policymakers desire improved delivery of health and related services for children with special health care needs (CSHCN). We analyzed factors associated with ease of use in obtaining such services. We also explored what were specific difficulties or delays in receiving services. By examining data from the National Survey of Children with Special Health Care Needs (NS-CSHCN 2009–2010) and using the revised criteria for “ease of use,” we were able to assess the percentage of parents who reported that their experiences seeking services for their children met those criteria. Methods We performed Chi square tests to examine associations between the independent variables and their relationship to the difficulties or delays assessed in the survey; including: eligibility, availability of services, waiting lists, cost, and access to information. We used logistic regression to determine the association of meeting the “ease of use” criteria with socio-demographic, complexity of need, and access variables. Results Overall, a third of families of CSHCN (35.3 %) encounter difficulties, delays, or frustrations in obtaining health and related services. The lack of access to health and community services in this study fell most heavily on children from racial/ethnic minority backgrounds, those in poverty, and those with complex emotional/behavioral or developmental needs and functional limitations. Conclusions for Practice CSHCN require services from a broad array of providers across multiple systems. Unfortunately, there are certain difficulties that hamper the accessibility of these systems. These findings underscore the need for both practice-level response and systems-level reform to ensure equitable distribution of health and community resources.     

Longitudinal associations between conflict monitoring and emergent academic skills: An event-related potentials study

Identifying the links between specific cognitive functions and emergent academic skills can help determine pathways to support both early academic performance and later academic achievement. Here, we investigated the longitudinal associations between a key aspect of cognitive control, conflict monitoring, and emergent academic skills from preschool through first grade, in a large sample of socioeconomically diverse children (N = 261). We recorded event-related potentials (ERPs) during a Go/No-Go task. The neural index of conflict monitoring, ΔN2, was defined as larger N2 mean amplitudes for No-Go versus Go trials. ΔN2 was observed over the right hemisphere across time points and showed developmental stability. Cross-lagged panel models revealed prospective links from ΔN2 to later math performance, but not reading performance. Specifically, larger ΔN2 at preschool predicted higher kindergarten math performance, and larger ΔN2 at kindergarten predicted higher first-grade math performance, above and beyond the behavioral performance in the Go/No-Go task. Early academic skills did not predict later ΔN2. These findings provided electrophysiological evidence for the contribution of conflict monitoring abilities to emergent math skills. In addition, our findings suggested that neural indices of cognitive control can provide additional information in predicting emergent math skills, above and beyond behavioral task performance.     

In Human Immunodeficiency Virus primary infection,early combined antiretroviral therapy reduced γδ T-cell activation but failed to restore their polyfunctionality

Primary and chronic human immunodeficiency virus (HIV) infection alters γδ T-cell features. However, there is no evidence about early combined antiretroviral therapy (cART) and γδ T-cell dynamics. In the present study, HIV-positive individuals were divided into those with early primary infection (EPI) and those with late primary infection (LPI). The analysis of γδ T cells was performed by flow cytometry before and after therapy. Polyfunctional profile was assessed after in vitro peripheral blood mononuclear cell (PBMC) exposure to specific antigens. The results show that primary infection induced an expansion of Vδ1 T cells in LPI. Before treatment, a massive activation of γδ T-cell subsets was observed in both groups of patients, that correlated with disease progression and was significantly reduced after cART introduction. Despite this, CD107A-expressing Vδ1 T cells in both groups were significantly fewer than in healthy donors, but were restored by therapy introduction. Polyfunctional analysis of Vδ1 T cells from HIV-positive individuals revealed a lower frequency of CD107A⁺ CCL-4⁺ Vδ1 T-cell subsets than healthy donors that persists after therapy. Functional profile of Vδ2 was similar to that in healthy donors before therapy but, at 6 months, a lower frequency of CD107A, interferon-γ- or tumor necrosis factor-α-producing Vδ2 T cells was observed in the EPI group. Finally, individuals with LPI showed a lower frequency of quadruple-functional Vδ2 T-cell subset. In conclusion, during primary HIV infection, the baseline Vδ1 T-cell activation is correlated with immune reconstitution potential. Moreover, an altered γδ polyfunctional profile occurred, persisting after cART. Further studies are needed to understand whether a longer treatment of primary infection may increase γδ T-cell functionality.     

Chromatin structure analysis of the mouse Xist locus

The Xist gene is expressed exclusively from the inactive X chromosome and plays a central role in regulating X chromosome inactivation. Here we describe experiments aimed at defining the extent of the active chromatin domain of the expressed Xist allele. By using an allele-specific general DNaseI sensitivity assay we show that there is preferential digestion of the expressed allele at sites within the transcribed locus but not in flanking sites located up to 70 kb 5'. A putative proximal boundary for the Xist domain is located within 10 kb upstream of promoter P1. Chromatin in the expressed domain was found to be acetylated at H4 in XX somatic cells but also in XY cells, where Xist is never expressed. A single clear exception to this was the Xist promoter, which is acetylated only in XX cells. These observations concur with the view that H4 acetylation may not be a general marker of active chromatin domains and further support data implicating local promoter acetylation as being of primary functional significance in vivo.     

Molecular epidemiologic evaluation of transmissibility and virulence of Mycobacterium tuberculosis.

Discovery of genotypic markers associated with increased transmissibility in Mycobacterium tuberculosis would represent an important step in advancing mycobacterial virulence studies. M. tuberculosis strains may be classified into one of three genotypes on the basis of the presence of specific nucleotide substitutions in codon 463 of the katG gene (katG-463) and codon 95 of the gyrA gene (gyrA-95). It has previously been reported that two of these three genotypes are associated with increased IS6110-based clustering, a potential proxy of virulence. We designed a case-control analysis of U.S.-born patients with tuberculosis in San Francisco, Calif., between 1991 and 1997 to investigate associations between katG-463 and gyrA-95 genotypes and epidemiologically determined measures of strain-specific infectivity and pathogenicity and IS6110-based clustering status. We used a new class of molecular probes called molecular beacons to genotype the isolates rapidly. Infectivity was defined as the propensity of isolates to cause tuberculin skin test conversions among named contacts, and pathogenicity was defined as their propensity to cause active disease among named contacts. The molecular beacon assay was a simple and reproducible method for the detection of known single nucleotide polymorphisms in large numbers of clinical M. tuberculosis isolates. The results showed that no genotype of the katG-463- and gyrA-95-based classification system was associated with increased infectivity and pathogenicity or with increased IS6110-based clustering in San Francisco during the study period. We speculate that molecular epidemiologic studies investigating clinically relevant outcomes may contribute to the knowledge of the significance of laboratory-derived virulence factors in the propagation of tuberculosis in human communities.     

Dynamic control of irregular bursting in an identified neuron of an oscillatory circuit.

In the oscillatory circuits known as central pattern generators (CPGs), most synaptic connections are inhibitory. We have assessed the effects of inhibitory synaptic input on the dynamic behavior of a component neuron of the pyloric CPG in the lobster stomatogastric ganglion. Experimental perturbations were applied to the single, lateral pyloric neuron (LP), and the resulting voltage time series were analyzed using an entropy measure obtained from power spectra. When isolated from phasic inhibitory input, LP generates irregular spiking-bursting activity. Each burst begins in a relatively stereotyped manner but then evolves with exponentially increasing variability. Periodic, depolarizing current pulses are poor regulators of this activity, whereas hyperpolarizing pulses exert a strong, frequency-dependent regularizing action. Rhythmic inhibitory inputs from presynaptic pacemaker neurons also regularize the bursting. These inputs 1) reset LP to a similar state at each cycle, 2) extend and further stabilize the initial, quasi-stable phase of its bursts, and 3) at sufficiently high frequencies terminate ongoing bursts before they become unstable. The dynamic time frame for stabilization overlaps the normal frequency range of oscillations of the pyloric CPG. Thus, in this oscillatory circuit, the interaction of rhythmic inhibitory input with intrinsic burst properties affects not only the phasing, but also the dynamic stability of neural activity.