Toxoplasma gondii resides in an intracellular compartment (parasitophorous vacuole) that excludes transmembrane molecules required for endosome - lysosome recruitment. Thus, the parasite survives by avoiding lysosomal degradation. However, autophagy can re-route the parasitophorous vacuole to the lysosomes and cause parasite killing. This raises the possibility that T. gondii may deploy a strategy to prevent autophagic targeting to maintain the non-fusogenic nature of the vacuole. We report that T. gondii activated EGFR in endothelial cells, retinal pigment epithelial cells and microglia. Blockade of EGFR or its downstream molecule, Akt, caused targeting of the parasite by LC3+ structures, vacuole-lysosomal fusion, lysosomal degradation and killing of the parasite that were dependent on the autophagy proteins Atg7 and Beclin 1. Disassembly of GPCR or inhibition of metalloproteinases did not prevent EGFR-Akt activation. T. gondii micronemal proteins (MICs) containing EGF domains (EGF-MICs; MIC3 and MIC6) appeared to promote EGFR activation. Parasites defective in EGF-MICs (MIC1 ko, deficient in MIC1 and secretion of MIC6; MIC3 ko, deficient in MIC3; and MIC1-3 ko, deficient in MIC1, MIC3 and secretion of MIC6) caused impaired EGFR-Akt activation and recombinant EGF-MICs (MIC3 and MIC6) caused EGFR-Akt activation. In cells treated with autophagy stimulators (CD154, rapamycin) EGFR signaling inhibited LC3 accumulation around the parasite. Moreover, increased LC3 accumulation and parasite killing were noted in CD154-activated cells infected with MIC1-3 ko parasites. Finally, recombinant MIC3 and MIC6 inhibited parasite killing triggered by CD154 particularly against MIC1-3 ko parasites. Thus, our findings identified EGFR activation as a strategy used by T. gondii to maintain the non-fusogenic nature of the parasitophorous vacuole and suggest that EGF-MICs have a novel role in affecting signaling in host cells to promote parasite survival.
Toxoplasma gondii resides in a parasitophorous vacuole that excludes transmembrane proteins required for recruitment of endosomes and lysosomes and thus, does not follow the path of classical lysosomal degradation. However, the non-fusogenic nature of the vacuole can be reverted when autophagy, a pathway to lysosomal degradation, is upregulated through the immune system or pharmacologically. Maintenance of the non-fusogenic nature of the vacuole is central to parasite survival. Thus, in addition to preventing degradation through a classical lysosomal pathway, T. gondii may also deploy strategies to prevent constitutive levels of autophagy from targeting the pathogen and causing its lysosomal degradation. We report that T. gondii accomplishes this task by causing EGFR activation in host cells. In cells that were not subjected to immune or pharmacologic upregulation of autophagy, blockade of EGFR resulted in parasite encasing by structures that expressed the autophagy protein LC3, vacuole-lysosomal fusion and autophagy protein-dependent killing of the parasite. Moreover, EGFR signaling also impaired targeting of the parasite by LC3+ structures in cells treated with stimulators of autophagy. Studies with T. gondii deficient in EGF domain containing-micronemal proteins (EGF-MICs) and recombinant EGF-MICs support the concept that these parasite adhesins contribute to EGFR activation.
The HIV-1 viral infectivity factor (Vif) neutralizes cell-encoded antiviral APOBEC3 proteins by recruiting a cellular ElonginB (EloB)/ElonginC (EloC)/Cullin5-containing ubiquitin ligase complex, resulting in APOBEC3 ubiquitination and proteolysis. The suppressors-of-cytokine-signalling-like domain (SOCS-box) of HIV-1 Vif is essential for E3 ligase engagement, and contains a BC box as well as an unusual proline-rich motif. Here, we report the NMR solution structure of the Vif SOCS–ElonginBC (EloBC) complex. In contrast to SOCS-boxes described in other proteins, the HIV-1 Vif SOCS-box contains only one α-helical domain followed by a β-sheet fold. The SOCS-box of Vif binds primarily to EloC by hydrophobic interactions. The functionally essential proline-rich motif mediates a direct but weak interaction with residues 101–104 of EloB, inducing a conformational change from an unstructured state to a structured state. The structure of the complex and biophysical studies provide detailed insight into the function of Vif's proline-rich motif and reveal novel dynamic information on the Vif–EloBC interaction.
HIV-1 viral infectivity factor; SOCS-box domain; ElonginBC; NMR; solution structure
Malaria within the Greater Mekong sub-region is extremely heterogeneous. While China and Thailand have been relatively successful in controlling malaria, Myanmar continues to see high prevalence. Coupled with the recent emergence of artemisinin-resistant malaria along the Thai-Myanmar border, this makes Myanmar an important focus of malaria within the overall region. However, accurate epidemiological data from Myanmar have been lacking, in part because of ongoing and emerging conflicts between the government and various ethnic groups. Here the results are reported from a risk analysis of malaria slide positivity in a conflict zone along the China-Myanmar border.
Surveys were conducted in 13 clinics and hospitals around Laiza City, Myanmar between April 2011 and October 2012. Demographic, occupational and educational information, as well as malaria infection history, were collected. Logistic models were used to assess risk factors for slide positivity.
Age patterns in Plasmodium vivax infections were younger than those with Plasmodium falciparum. Furthermore, males were more likely than females to have falciparum infections. Patients who reported having been infected with malaria during the previous year were much more likely to have a current vivax infection. During the second year of the study, falciparum infections among soldiers increased signficiantly.
These results fill some knowledge gaps with regard to risk factors associated with malaria slide positivity in this conflict region of north-eastern Myanmar. Since epidemiological studies in this region have been rare or non-existent, studies such as the current are crucial for understanding the dynamic nature of malaria in this extremely heterogeneous epidemiological landscape.
Plasmodium falciparum; Plasmodium vivax; The Greater Mekong Subregion; Myanmar; China; Border malaria
Global positioning systems (GPS) have emerged as a research tool to better understand environmental influences on physical activity. This study examined the feasibility of using GPS in terms of perceived acceptability, barriers, and ease of use in a racially/ethnically diverse sample of lower socioeconomic position (SEP).
Data were from two pilot studies involving a total of 170 African American, Hispanic, and White urban adults with a mean (standard deviation) age of 47.8 (±13.1) years. Participants wore a GPS for up to seven days. They answered questions about GPS acceptability, barriers (wear-related concerns), and ease of use, before and after wearing the GPS.
We found high ratings of GPS acceptability and ease of use and low levels of wear-related concerns, which were maintained after data collection. While most were comfortable with their movements being tracked, older participants (p<0.05) and African Americans (p<0.05) reported lower comfort levels. Participants who were younger, with higher education, and low incomes were more likely to indicate that the GPS made the study more interesting (p<0.05). Participants described technical and wear-related problems, but few concerns related to safety, loss, or appearance.
Use of GPS was feasible in this racially/ethnically diverse, lower SEP sample.
Global positioning system; Environment; Physical activity; Feasibility; Perceptions
High rates of physical inactivity compromise the health status of populations globally. Social networks have been shown to influence physical activity (PA), but little is known about how best to engineer social networks to sustain PA. To improve procedures for building networks that shape PA as a normative behavior, there is a need for more specific hypotheses about how social variables influence PA. There is also a need to integrate concepts from network science with ecological concepts that often guide the design of in-person and electronically-mediated interventions. Therefore, this paper: (1) proposes a conceptual model that integrates principles from network science and ecology across in-person and electronically-mediated intervention modes; and (2) illustrates the application of this model to the design and evaluation of a social network intervention for PA.
A conceptual model for engineering social networks was developed based on a scoping literature review of modifiable social influences on PA. The model guided the design of a cluster randomized controlled trial in which 308 sedentary adults were randomly assigned to three groups: WalkLink+: prompted and provided feedback on participants’ online and in-person social-network interactions to expand networks for PA, plus provided evidence-based online walking program and weekly walking tips; WalkLink: evidence-based online walking program and weekly tips only; Minimal Treatment Control: weekly tips only. The effects of these treatment conditions were assessed at baseline, post-program, and 6-month follow-up. The primary outcome was accelerometer-measured PA. Secondary outcomes included objectively-measured aerobic fitness, body mass index, waist circumference, blood pressure, and neighborhood walkability; and self-reported measures of the physical environment, social network environment, and social network interactions. The differential effects of the three treatment conditions on primary and secondary outcomes will be analyzed using general linear modeling (GLM), or generalized linear modeling if the assumptions for GLM cannot be met.
Results will contribute to greater understanding of how to conceptualize and implement social networks to support long-term PA. Establishing social networks for PA across multiple life settings could contribute to cultural norms that sustain active living.
Social networks; Social environment; Social support; Built environment; Walking; Exercise; Accelerometers; Social media; Internet; Sustainability
Appalachian counties have historically had elevated infant mortality rates. Changes in infant mortality disparities over time in Appalachia are not well-understood. This study explores spatial inequalities in white infant mortality rates over time in the 13 Appalachian states, comparing counties in Appalachia with non-Appalachian counties.
Data are analyzed for 1,100 counties in 13 Appalachian states that include 420 counties designated as Appalachian by the Appalachian Regional Commission. Area Resource File data for 1976-1980 and 1996-2000 provide county- and city-level infant mortality rates, poverty rates, rural-urban continuum codes, and numbers of physicians per 1,000 residents. Multiple regression analyses evaluate whether Appalachian counties are significantly associated with elevated white infant mortality in each time period, accounting for covariates.
White infant mortality rates decreased substantially in all sub-regions over the last 2 decades; however, disparities in infant mortality did not diminish in Appalachian counties compared to non-Appalachian counties. After accounting for poverty, rural/urban status, and health care resources, Appalachian counties were significantly associated with comparatively higher infant mortality during the late 1970s but not in the late 1990s. At the more recent time point, higher poverty rates, residence in more rural areas, and lower physician density were associated with greater infant mortality risk.
Appalachian counties continue to experience relatively elevated infant mortality rates. Poverty and rurality remain important dimensions of health service need in Appalachia.
Appalachia; disparity; infant mortality; rural
Lipopolysaccharide (LPS) in high doses inhibits placental multidrug resistance P-glycoprotein (P-gp - Abcb1a/b) and breast cancer resistance protein (BCRP - Abcg2). This potentially impairs fetal protection against harmful factors in the maternal circulation. However, it is unknown whether LPS exposure, at doses that mimic sub-lethal clinical infection, alters placental multidrug resistance. We hypothesized that sub-lethal (fetal) LPS exposure reduces placental P-gp activity. Acute LPS (n = 19;150 µg/kg; ip) or vehicle (n = 19) were given to C57BL/6 mice at E15.5 and E17.5. Placentas and fetal-units were collected 4 and 24 h following injection. Chronic LPS (n = 6; 5 µg/kg/day; ip) or vehicle (n = 5) were administered from E11.5–15.5 and tissues were collected 4 h after final treatment. P-gp activity was assessed by [3H]digoxin accumulation. Placental Abcb1a/b, Abcg2, interleukin-6 (Il-6), Tnf-α, Il-10 and toll-like receptor-4 (Tlr-4) mRNA were measured by qPCR. Maternal plasma IL-6 was determined. At E15.5, maternal IL-6 was elevated 4 h after single (p<0.001) and chronic (p<0.05) LPS, but levels had returned to baseline by 24 h. Placental Il-6 mRNA was also increased after acute and chronic LPS treatments (p<0.05), whereas Abcb1a/b and Abcg2 mRNA were unaffected. However, fetal [3H]digoxin accumulation was increased (p<0.05) 4 h after acute LPS, and maternal [3H]digoxin myocardial accumulation was increased (p<0.05) in mice exposed to chronic LPS treatments. There was a negative correlation between fetal [3H]digoxin accumulation and placental size (p<0.0001). Acute and chronic sub-lethal LPS exposure resulted in a robust inflammatory response in the maternal systemic circulation and placenta. Acute infection decreased placental P-gp activity in a time- and gestational age-dependent manner. Chronic LPS decreased P-gp activity in the maternal myocardium and there was a trend for fetuses with smaller placentas to accumulate more P-gp substrate than their larger counterparts. Collectively, we demonstrate that acute sub-lethal LPS exposure during pregnancy impairs fetal protection against potentially harmful xenobiotics in the maternal circulation.
The U.S. has experienced a resurgence of income inequality in the past decades. The evidence regarding the mortality implications of this phenomenon has been mixed. This study employs a rarely used method in mortality research, quantile regression (QR), to provide insight into the ongoing debate of whether income inequality is a determinant of mortality and to investigate the varying relationship between inequality and mortality throughout the mortality distribution. Analyzing a U.S. dataset where the five-year (1998–2002) average mortality rates were combined with other county-level covariates, we found that the association between inequality and mortality was not constant throughout the mortality distribution and the impact of inequality on mortality steadily increased until the 80th percentile. When accounting for all potential confounders, inequality was significantly and positively related to mortality; however, this inequality–mortality relationship did not hold across the mortality distribution. A series of Wald tests confirmed this varying inequality–mortality relationship, especially between the lower and upper tails. The large variation in the estimated coefficients of the Gini index suggested that inequality had the greatest influence on those counties with a mortality rate of roughly 9.95 deaths per 1000 population (80th percentile) compared to any other counties. Furthermore, our results suggest that the traditional analytic methods that focus on mean or median value of the dependent variable can be, at most, applied to a narrow 20 percent of observations. This study demonstrates the value of QR. Our findings provide some insight as to why the existing evidence for the inequality–mortality relationship is mixed and suggest that analytical issues may play a role in clarifying whether inequality is a robust determinant of population health.
Quantile regression; Income inequality; Mortality; County; USA
We report the solution structures of the VPg proteins from feline calicivirus (FCV) and murine norovirus (MNV), which have been determined by nuclear magnetic resonance spectroscopy. In both cases, the core of the protein adopts a compact helical structure flanked by flexible N and C termini. Remarkably, while the core of FCV VPg contains a well-defined three-helix bundle, the MNV VPg core has just the first two of these secondary structure elements. In both cases, the VPg cores are stabilized by networks of hydrophobic and salt bridge interactions. The Tyr residue in VPg that is nucleotidylated by the viral NS7 polymerase (Y24 in FCV, Y26 in MNV) occurs in a conserved position within the first helix of the core. Intriguingly, given its structure, VPg would appear to be unable to bind to the viral polymerase so as to place this Tyr in the active site without a major conformation change to VPg or the polymerase. However, mutations that destabilized the VPg core either had no effect on or reduced both the ability of the protein to be nucleotidylated and virus infectivity and did not reveal a clear structure-activity relationship. The precise role of the calicivirus VPg core in virus replication remains to be determined, but knowledge of its structure will facilitate future investigations.
The goals of this study are to explore whether health condition is an antecedent extraneous factor for the relationship between health care system distrust and self-rated health among the elderly, and to investigate if the associations among these variables are place-specific. We used logistic geographically weighted regression to analyze data on an elderly sample residents in the Philadelphia metropolitan area. We found that the health conditions of the elderly account for the association between high distrust and poor/fair self-rated health and that the distrust/self-rated health relationship varied spatially. This finding suggests that a place-centered perspective can inform distrust/self-rated health research.
self-rated health; health care system distrust; elderly; geographically weighted regression; Philadelphia metropolitan area
The Enteroaggregative Escherichia coli AAF/II pilus plays an important role in the attachment to and invasion of the host during the initial stages of colonization. Here, the major adhesive subunit of AAF/II has been crystallized at pH 3.4 and diffraction data have been collected to 2.1 Å resolution.
AafA is the major adhesive pilin subunit of the aggregative adherence fimbriae (AAF) from enteroaggregative Escherichia coli, which play an important role by attaching to the host cells during the initial phase of bacterial colonization and invasion. AafA has been crystallized at pH 3.4 and diffraction data have been collected to 2.1 Å resolution. Molecular replacement was unsuccessful and selenomethionine-substituted protein and heavy-atom derivatives are being prepared for phasing.
AafA; enteroaggregative Escherichia coli; pilin subunit; fimbriae
Background and Purpose
Retention of substances from systemic circulation in the brain and testes are limited due to high levels of P-glycoprotein (P-gp) in the luminal membranes of brain and testes capillary endothelial cells. From a clinical perspective, P-gp rapidly extrudes lipophilic therapeutic agents, which then fail to reach efficacious levels. Recent studies have demonstrated that acute administration of selective serotonin reuptake inhibitors (SSRI) can affect P-gp function, in vitro and in vivo. However, little is known concerning the time-course of these effects or the effects of different SSRI in vivo.
The P-gp substrate, tritiated digoxin ([3H] digoxin), was co-administered with fluoxetine or sertraline to determine if either compound increased drug accumulation within the brains and testes of mice due to inhibition of P-gp activity. We undertook parallel studies in endothelial cells derived from brain microvessels to determine the dose-response and time-course of effects.
In vitro, sertraline resulted in rapid and potent inhibition of P-gp function in brain endothelial cells, as determined by cellular calcein accumulation. In vivo, a biphasic effect was demonstrated. Brain accumulation of [3H] digoxin was increased 5 minutes after treatment with sertraline, but by 60 minutes after sertraline treatment, brain accumulation of digoxin was reduced compared to control. By 240 minutes after sertraline treatment brain digoxin accumulation was elevated compared to control. A similar pattern of results was obtained in the testes. There was no significant effect of fluoxetine on P-gp function, in vitro or in vivo.
Conclusions and Implications
Acute sertraline administration can modulate P-gp activity in the blood-brain barrier and blood-testes barrier. This clearly has implications for the ability of therapeutic agents that are P-gp substrates, to enter the brain when co-administered with SSRI.
We use a geographically weighted regression (GWR) approach to examine how the relationships between a set of predictors and prenatal care vary across the continental US. At its most fundamental, GWR is an exploratory technique that can facilitate the identification of areas with low prenatal care utilization and help better understand which predictors are associated with prenatal care at specific locations. Our work complements existing prenatal care research in providing an ecological, place-sensitive analysis. We found that the percent of the population who was uninsured was positively associated with the percent of women receiving late or no prenatal care in the global model. The GWR map not only confirmed, but also demonstrated the spatial varying association. Additionally, we found that the number of Ob-Gyn doctors per 100,000 females of childbearing age in a county was associated with the percentage of women receiving late or no prenatal care, and that a higher value of female disadvantage is associated with higher percentages of late or no prenatal care. GWR offers a more nuanced examination of prenatal care and provides empirical evidence in support of locally tailored health policy formation and program implementation, which may improve program effectiveness.
Geographically weighted regression; Spatial non-stationarity; Local modeling; Prenatal care
The adhesin fimbriae-associated protein 1 (Fap1) is a surface protein of Streptococcus parasanguinis FW213 and plays a major role in the formation of dental plaque in humans. Here, the adhesive domain Fap1-NRα, which is activated by acidic pH, has been crystallized at pH 5.0 and diffraction data have been collected to 3.0 Å resolution.
The adhesin fimbriae-associated protein 1 (Fap1) is a surface protein of Streptococcus parasanguinis FW213 and plays a major role in the formation of dental plaque in humans. Increased adherence is highly correlated to a reduction in pH and acid activation has been mapped to a subdomain: Fap1-NRα. Here, Fap1-NRα has been crystallized at pH 5.0 and diffraction data have been collected to 3.0 Å resolution. The crystals belonged to space group P41212 or P43212, with unit-cell parameters a = b = 122.0, c = 117.8 Å. It was not possible to conclusively determine the number of molecules in the asymmetric unit and heavy-atom derivatives are now being prepared.
fimbriae-associated protein 1; Streptococcus parasanguinis FW213; adhesive domain; dental plaque
The fimbriae-associated protein 1 (Fap1) is a major adhesin of Streptococcus parasanguinis, a primary colonizer of the oral cavity that plays an important role in the formation of dental plaque. Fap1 is an extracellular adhesive surface fibre belonging to the serine-rich repeat protein (SRRP) family, which plays a central role in the pathogenesis of streptococci and staphylococci. The N-terminal adhesive region of Fap1 (Fap1-NR) is composed of two domains (Fap1-NRα and Fap1-NRβ) and is projected away from the bacterial surface via the extensive serine-rich repeat region, for adhesion to the salivary pellicle. The adhesive properties of Fap1 are modulated through a pH switch in which a reduction in pH results in a rearrangement between the Fap1-NRα and Fap1-NRβ domains, which assists in the survival of S. parasanguinis in acidic environments. We have solved the structure of Fap1-NRα at pH 5.0 to 3.0 Ǻ resolution and reveal how subtle rearrangements of the 3-helix bundle combined with a change in electrostatic potential mediates ‘opening’ and activation of the adhesive region. Further, we show that pH-dependent changes are critical for biofilm formation and present an atomic model for the inter-Fap1-NR interactions which have been assigned an important role in the biofilm formation.
Americans’ distrust in the health care system has increased in the past decades; however, little research has explored the impact of distrust on self-rated health and even less is known about whether neighborhood social environment plays a role in understanding the relationship between distrust and self-rated health. This study fills these gaps by investigating both the direct and moderating associations of neighborhood social environment with self-rated health. Our analysis is based on the 2008 Philadelphia Health Management Corporation’s household survey and neighborhood-level data. Findings from multilevel logistic regression show that after controlling for individual- and neighborhood-level covariates, distrust is directly and adversely related to self-rated health, and that neighborhood social affluence and stability are directly and negatively associated with the odds of reporting poor/fair health. Neighborhood disadvantage and crime rates are not directly related to self-rated health, but increase the odds of having poor/fair health via distrust. Overall, our results suggest that macro-level actions can alter individual’s perception of residential environment and lead to improved health. To improve the public health in an urban setting, rebuilding confidence in the health care system is integral, and the policies that help establish safe and cohesive neighborhoods may reduce the adverse effect of distrust on self-rated health.
Health care system distrust; Self-rated health; Neighborhood social environment; Multilevel modeling; Philadelphia
This study examined relationships among individual demographics, environmental features (e.g., fast food outlet density, park land use) of residential neighborhoods and activity spaces, and obesity-related behaviors (diet, physical activity). Participants’ movement was tracked for seven days using global positioning systems (GPS). Two activity space measures (one standard deviation ellipse, daily path area) were derived from the GPS data. Activity spaces were generally larger than residential neighborhoods; environmental features of residential neighborhoods and activity spaces were weakly associated; and some activity space environmental features were related to dietary behaviors. Activity spaces may provide new insights into environmental influences on obesity-related behaviors.
Global positioning system; Activity space; Neighborhood; Diet; Physical activity; Environment
Placental P-glycoprotein (P-gp) acts to protect the developing fetus from exogenous compounds. This protection declines with advancing gestation leaving the fetus and fetal brain vulnerable to these compounds and potential teratogens in maternal circulation. This vulnerability may be more pronounced in pregnancies complicated by infection, which is common during pregnancy. Pro-inflammatory cytokines (released during infection) have been shown to be potent inhibitors of P-gp, but nothing is known regarding their effects at the developing blood-brain barrier (BBB). We hypothesized that P-gp function and expression in endothelial cells of the developing BBB will be inhibited by pro-inflammatory cytokines. We have derived brain endothelial cell (BEC) cultures from various stages of development of the guinea pig: gestational day (GD) 50, 65 (term ∼68 days) and postnatal day (PND) 14. Once these cultures reached confluence, BECs were treated with various doses (100–104 pg/mL) of pro-inflammatory cytokines: interleukin-1β (IL-1β), interleukin-6 (IL-6) or tumor necrosis factor- α (TNF-α). P-gp function or abcb1 mRNA (encodes P-gp) expression was assessed following treatment. Incubation of GD50 BECs with IL-1β, IL-6 or TNF-α resulted in no change in P-gp function. GD65 BECs displayed a dose-dependent decrease in function with all cytokines tested; maximal effects at 42%, 65% and 34% with IL-1β, IL-6 and TNF-α treatment, respectively (P<0.01). Inhibition of P-gp function by IL-1β, IL-6 and TNF-α was even greater in PND14 BECs; maximal effects at 36% (P<0.01), 84% (P<0.05) and 55% (P<0.01), respectively. Cytokine-induced reductions in P-gp function were associated with decreased abcb1 mRNA expression. These data suggest that BBB P-gp function is increasingly responsive to the inhibitory effects of pro-inflammatory cytokines, with increasing developmental age. Thus, women who experience infection and take prescription medication during pregnancy may expose the developing fetal brain to greater amounts of exogenous compounds – many of which are considered potentially teratogenic.
This study investigates whether health care system distrust is a barrier to breast and cervical cancer screening and whether different dimensions of distrust – values and competence – have different impacts on cancer screening.
We utilize data on 5,268 women 18 and older living in Philadelphia and analyze their use of screening services via logistic and multinomial logistic regression.
High levels of health care system distrust are associated with lower utilization of breast and cervical cancer screening services. The associations differ by dimensions of distrust. Specifically, high competence distrust is associated with a reduced likelihood of having Pap smear tests, and women with high values distrust are less likely to have breast examinations within the recommended time period. Independent of other covariates, individual health care resources and health status are associated with utilization of cancer screening.
Health care system distrust is a barrier to breast and cervical cancer screening even after controlling for demographic and socioeconomic determinants. Rebuilding confidence in the health care system may improve personal and public health by increasing the utilization of preventive health services.
Approximately 10% of pregnant women are at risk of preterm delivery and receive synthetic glucocorticoids (sGC) to promote fetal lung development. Studies have indicated that prenatal sGC therapy modifies hypothalamic-pituitary-adrenal (HPA) function in first-generation (F1) offspring. The objective of this study was to determine whether differences in HPA function and behavior are evident in the subsequent (F2) generation. Pregnant guinea pigs (F0) received betamethasone (BETA; 1 mg/kg) or saline on gestational d 40/41, 50/51, and 60/61. F1 females were mated with control males to create F2 offspring. HPA function was assessed in juvenile and adult F2 offspring. Locomotor activity was assessed in juvenile offspring. Analysis of HPA-related gene expression was undertaken in adult hippocampi, hypothalami, and pituitaries. Locomotor activity was reduced in F2 BETA males (P < 0.05). F2 BETA offspring displayed blunted cortisol response to swim stress (P < 0.05). After dexamethasone challenge, F2 BETA males and females displayed increased and decreased negative feedback, respectively. F2 BETA females had reduced pituitary levels of proopiomelanocortin (and adrenocorticotropic hormone), and corticotropin-releasing hormone receptor mRNA and protein (P < 0.05). F2 BETA males displayed increased hippocampal glucocorticoid receptor (P < 0.001), whereas in BETA females, hippocampal glucocorticoid receptor and mineralocorticoid receptor mRNA were decreased (P < 0.05). In conclusion, prenatal BETA treatment affects HPA function and behavior in F2 offspring. In F2 BETA females, pituitary function appears to be primarily affected, whereas hippocampal glucocorticoid feedback systems appear altered in both F2 BETA males and females. These data have clinical implication given the widespread use of repeat course glucocorticoid therapy in the management of preterm labour.
Prenatal synthetic glucocorticoids (sGC) are administered to pregnant women at risk of delivering preterm, approximately 10% of all pregnancies. Animal studies have demonstrated that offspring exposed to elevated glucocorticoids, either by administration of sGC or as a result of maternal stress, are at increased risk of developing behavioral, endocrine, and metabolic abnormalities. DNA methylation is a covalent modification of DNA that plays a critical role in long-lasting programming of gene expression. Here we tested the hypothesis that prenatal sGC treatment has both acute and long-term effects on DNA methylation states in the fetus and offspring and that these effects extend into a subsequent generation. Pregnant guinea pigs were treated with sGC in late gestation, and methylation analysis by luminometric methylation assay was undertaken in organs from fetuses and offspring across two generations. Expression of genes that modify the epigenetic state were measured by quantitative real-time PCR. Results indicate that there are organ-specific developmental trajectories of methylation in the fetus and newborn. Furthermore, these trajectories are substantially modified by intrauterine exposure to sGC. These sGC-induced changes in DNA methylation remain into adulthood and are evident in the next generation. Furthermore, prenatal sGC exposure alters the expression of several genes encoding proteins that modulate the epigenetic state. Several of these changes are long lasting and are also present in the next generation. These data support the hypothesis that prenatal sGC exposure leads to broad changes in critical components of the epigenetic machinery and that these effects can pass to the next generation.
A link exists between stress during pregnancy and altered hypothalamic–pituitary–adrenal (HPA) activity and behaviour in children. In the guinea pig, male offspring born to mothers that were exposed to stress during pregnancy demonstrated increased anxiety, basal cortisol levels and decreased testosterone concentrations. Testosterone is known to inhibit HPA function and anxiety behaviours. Therefore, we hypothesized that restoring plasma testosterone would ameliorate the differences observed in HPA function and behaviour. Pregnant guinea pigs were exposed to a stressor during the period of rapid fetal brain growth (prenatal stress, PS) or left undisturbed (control, C). Behaviour in an open-field and prepulse inhibition (PPI) of the acoustic startle reflex (ASR) was assessed in juvenile offspring. In adulthood, male offspring were divided into four groups: Control + sham gonadectomy (GDX), control + GDX + testosterone replacement, PS + sham GDX and PS + GDX + testosterone. Male offspring were retested in the open-field and PPI. Basal HPA activity was also assessed. As juveniles, PS males exhibited significantly lower ASR (P < 0.05) and elevated PPI. In adulthood, PS male offspring exhibited significantly decreased PPI (P < 0.02) and this was reversed by administration of testosterone. We also found that adult PS offspring exhibited significantly less activity in the open-field (P < 0.05) and administration of testosterone increased ambulatory activity in PS animals. Basal plasma adrenocorticotrophin hormone (ACTH) levels were significantly greater in PS animals and there was a trend towards reversal by administration of testosterone in PS males. In conclusion, prenatal stress results in male guinea pig offspring that exhibit age-dependent differences in ambulatory activity, sensorimotor gating and HPA activity. In adulthood, the behavioural changes are reversed by replacement of plasma testosterone.
The discovery that small size at birth and during infancy are associated with a higher risk of diabetes and related metabolic disease in later life has pointed to the importance of developmental factors in these conditions. The birth size associations are thought to reflect exposure to adverse environmental factors during early development but the mechanisms involved are still not fully understood. Animal and human work has pointed to the importance of changes in the set-point of a number of key hormonal systems controlling growth and development. These include the IGF-1/GH axis, gonadal hormones and, in particular, the systems mediating the classical stress response. Several studies show that small size at birth is linked with increased activity of the hypothalamic-pituitary-adrenal axis and sympathoadrenal system in adult life. More recent human studies have shown associations between specific adverse experiences during pregnancy, such as famine or the consumption of adverse diets, and enhanced stress responses many decades later. The mediators of these neuroendocrine responses are biologically potent and are likely to have a direct influence on the risk of metabolic disease. These neuroendocrine changes may also have an evolutionary basis being part of broader process, termed phenotypic plasticity, by which adverse environmental cues experienced during development modify the structure and physiology of the adult towards a phenotype adapted for adversity. The changes are clearly advantageous if they lead to a phenotype which is well-adapted for the adult environment, but may lead to disease if there is subsequent overnutrition or other unexpected environmental conditions.
Neuroendocrine fetal programming; Metabolic disease; Diabetes; Hypothalamic-pituitary-adrenal axis; Stress responses; Birth weight