Obesogenic Diet in Mice Leads to Inflammation and Oxidative Stress in the Mother in Association with Sex-Specific Changes in Fetal Development, Inflammatory Markers and Placental Transcriptome

BACKGROUND

Obesity during pregnancy is related to adverse maternal and neonatal outcomes. Factors involved in these outcomes may include increased maternal insulin resistance, inflammation, oxidative stress, and nutrient mishandling. The placenta is the primary determinant of fetal outcomes, and its function can be impacted by maternal obesity. The aim of this study on mice was to determine the effect of obesity on maternal lipid handling, inflammatory and redox state, and placental oxidative stress, inflammatory signaling, and gene expression relative to female and male fetal growth.

METHODS

Female mice were fed control or obesogenic high-fat/high-sugar diet (HFHS) from 9 weeks prior to, and during, pregnancy. On day 18.5 of pregnancy, maternal plasma, and liver, placenta, and fetal serum were collected to examine the immune and redox states. The placental labyrinth zone (Lz) was dissected for RNA-sequencing analysis of gene expression changes.

RESULTS

the HFHS diet induced, in the dams, hepatic steatosis, oxidative stress (reduced catalase, elevated protein oxidation) and the activation of pro-inflammatory pathways (p38-MAPK), along with imbalanced circulating cytokine concentrations (increased IL-6 and decreased IL-5 and IL-17A). HFHS fetuses were asymmetrically growth-restricted, showing sex-specific changes in circulating cytokines (GM-CSF, TNF-α, IL-6 and IFN-γ). The morphology of the placenta Lz was modified by an HFHS diet, in association with sex-specific alterations in the expression of genes and proteins implicated in oxidative stress, inflammation, and stress signaling. Placental gene expression changes were comparable to that seen in models of intrauterine inflammation and were related to a transcriptional network involving transcription factors, LYL1 and PLAG1.

CONCLUSION

This study shows that fetal growth restriction with maternal obesity is related to elevated oxidative stress, inflammatory pathways, and sex-specific placental changes. Our data are important, given the marked consequences and the rising rates of obesity worldwide.

Examining the effectiveness of Gateway-an out-of-court community-based intervention to reduce recidivism and improve the health and well-being of young adults committing low-level offences: study protocol for a randomised controlled trial

BACKGROUND

Young adult offenders represent a third of the UK prison population and are at risk of poor health outcomes including drug and alcohol misuse, self-harm and suicide. Court diversion interventions aim to reduce the negative consequences of formal criminal justice sanctions and focus resources on addressing the root causes of offending. Although diversions are widely used, evidence of their effectiveness has not yet been established. Hampshire Constabulary, working together with local charities, have developed the Gateway programme, an out-of-court intervention aimed at improving the life chances of young adults. Issued as a conditional caution, participants undertake a health and social care needs assessment, attend workshops encouraging analysis of own behaviour and its consequences and agree not to re-offend during the 16-week caution.

METHODS

This is a pragmatic, multi-site, parallel-group, superiority randomised controlled trial with a target sample size of 334. Participants are aged 18-24, reside in Hampshire and Isle of Wight and are being questioned for an eligible low-level offence. Police investigators offer potential participants a chance to receive the Gateway caution, and those interested are also invited to take part in the study. Police officers obtain Stage 1 consent and carry out an eligibility check, after which participants are randomised on a 1:1 basis either to receive Gateway or follow the usual process, such as court appearance or a different conditional caution. Researchers subsequently obtain Stage 2 consent and collect data at weeks 4 and 16, and 1 year post-randomisation. The primary outcome is the Warwick-Edinburgh Mental Well-being Scale (WEMWBS). Secondary outcomes include health status, alcohol and drug use, recidivism and resource use. The primary analysis will compare the WEMWBS score between the two groups at 12 months.

DISCUSSION

This pioneering trial aims to address the evidence gap surrounding diversion in 18-24-year-olds. The findings will inform law enforcement agencies, third sector organisations, policymakers and commissioners, as well as researchers working in related fields and with vulnerable target populations.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial Register ( ISRCTN 11888938 ).

Maternal temperature in emergency caesarean section (MATES): an observational multicentre study

BACKGROUND

Temperature regulation in women undergoing emergency caesarean section is a complex topic about which there is a paucity of evidence-based recommendations. The adverse effects of inadvertent peri-operative hypothermia are well described. Hyperthermia is also associated with adverse neonatal outcomes, an increased risk of obstetric intervention and increased treatment for suspected sepsis. We conducted a multi-centre observational cohort study to identify the prevalence of hypothermia and hyperthermia during emergency caesarean section. S: Participants undergoing emergency caesarean section were recruited across 14 sites in the UK. The primary end point was maternal temperature in the recovery room. Temperature was measured using a zero heat-flux temperature monitoring device.

RESULTS

Two hundred and sixty-five participants were recruited over a 12-month period. The prevalence of hypothermia (<36.0°C) was 10.7% and the prevalence of hyperthermia (>37.5°C) was 14.7% on admission to recovery. The prevalence of hypothermia, normothermia, and hyperthermia differed among type of anaesthesia: 71.4% of the hypothermic group had received a spinal anaesthetic whereas 76.9% of the hyperthermic group had received epidural top-up anaesthesia. There was a significant decrease in maternal temperature between the time of delivery and admission to the recovery room of 0.20°C (95% CI 0.15 to 0.25, P<0.001).

CONCLUSIONS

Both hypothermia and hyperthermia are prevalent findings in mothers who undergo emergency caesarean section. Therefore, accurate temperature measurement is essential to ensure that an appropriate intra-operative temperature management strategy is employed.

Temperature thresholds for germination in 20 short-range endemic plant species from a Greenstone Belt in southern Western Australia

The study of climate-driven effects on seed traits such as germination has gained momentum over the past decade as the impact of global warming becomes more apparent on the health and survival of plant diversity. Seed response to warming was evaluated in a suite of short-range endemic species from the biodiverse Greenstone Belt of southern Western Australia. The temperature dimensions for germination in 20 woody perennials were identified using small unreplicated samples over 6 weeks on a temperature gradient plate (constant and fluctuating temperatures between 5 and 40 °C). These data were subsequently modelled against current and forecast (2070) mean monthly minimum and maximum temperatures to illustrate seasonal changes to germination timing and final percentage germination. All but one species attained full germination in at least one cell on the gradient plate. Modelling of the data suggested only minimal changes to percentage germination despite a forecast rise in diurnal temperatures over the next 50 years. Nine species were predicted to experience declines of between <1% and 7%, whilst 11 species were predicted to increase their germination by <1% to 3%. Overall, the speed of germination is predicted to increase but the timing of germination for most species shifts seasonally (both advances and delays) as a result of changing diurnal temperatures. The capacity of this suite of species to cope with warmer temperatures during a critical early life stage shows a degree of adaptation to heterogeneous environments. Predicting the effects of global change on terrestrial plant communities is crucial to managing and conserving plant diversity.

Components of the Risk Instrument for Screening in the Community (RISC) that Correlate with Public Health Nurses' Perception of Risk

BACKGROUND

Functional decline and frailty are common in community-dwelling older adults, leading to an increased risk of adverse outcomes.

OBJECTIVE

To examine the factors that public health nurses perceive to cause risk of three adverse outcomes: institutionalisation, hospitalisation, and death, in older adults, using the Risk Instrument for Screening in the Community (RISC).

DESIGN

A quantitative, correlational, descriptive design was used.

SETTING AND PARTICIPANTS

A sample of 803 community-dwellers, aged over 65 years receiving regular follow-up by public health nurses. Procedure and Measurements: Public health nurses (n=15) scored the RISC and the Clinical Frailty Scale (CFS) on patients in their caseload. We examined and compared correlations between the severity of concern and ability of the caregiver network to manage these concerns with public health nurses' perception of risk of the three defined adverse outcomes.

RESULTS

In total, 782 RISC scores were available. Concern was higher for the medical state domain (686/782,88%) compared with the mental state (306/782,39%) and activities of daily living (595/782,76%) domains. Concern was rated as severe for only a small percentage of patients. Perceived risk of institutionalisation had the strongest correlation with concern over patients mental state,(r=0.53), while risk of hospitalisation,(r=0.53) and death,(r=0.40) correlated most strongly with concern over the medical state. Weaker correlations were found for the other domains and RISC scores. The CFS most strongly correlated with the ADL domain,(r=0.78).

CONCLUSION

Although the prevalence of concern was high, it was mostly rated as mild. Perceived risk of institutionalisation correlated most with concern over the ability of caregiver networks to manage patients' mental state, while risk of hospitalisation and death correlated with patients' medical state. The findings suggest the importance of including an assessment of the caregiver network when examining community-dwelling older adults. Validation of the RISC and public health nurses' ratings are now required.

Parental experiences of their infant's hospitalization for cardiac surgery

BACKGROUND

Parents are increasingly recognized as important partners in children's health care. Despite their involvement in care, parental experiences of their child's hospitalization have received little research attention. In this study we explored parents' perceptions of what they found difficult, what they would like to be different and what they found to be helpful during their infant's hospitalization and surgery for the treatment of congenital heart disease.

METHODS

Structured interviews were conducted with 154 parents (91 mothers, 63 fathers) whose infant underwent cardiac surgery (at <3 months of age) 1 month post discharge from hospital. Thematic and frequency analyses were performed.

RESULTS

Parents reported a range of difficulties from dealing with their baby's unfolding illness, surgery and recovery to the structural and systemic issues associated with the broader context of their experiences. In an effort to be near their baby, parents struggled to obtain the necessities for daily living at the hospital and negotiate transitions between their hospital and home lives throughout the admission. Domains parents identified for change included the availability of facilities and resources and the quantity and quality of information and emotional support. Parents reported relationships with hospital staff as the most common source of support during this challenging time.

CONCLUSIONS

Opportunities to improve parents' experiences when their infant is in hospital exist at an organizational level as well as at the clinical level. The significance of parents' relationship with hospital staff indicates the potential for each professional to impact on families' experiences on a daily basis. The range of challenges indicates the scope and need for allied health services.

Ex-vivo analysis of human natural killer T cells demonstrates heterogeneity between tissues and within established CD4(+) and CD4(-) subsets

Our understanding of human type 1 natural killer T (NKT) cells has been heavily dependent on studies of cells from peripheral blood. These have identified two functionally distinct subsets defined by expression of CD4, although it is widely believed that this underestimates the true number of subsets. Two recent studies supporting this view have provided more detail about diversity of the human NKT cells, but relied on analysis of NKT cells from human blood that had been expanded in vitro prior to analysis. In this study we extend those findings by assessing the heterogeneity of CD4(+) and CD4(-) human NKT cell subsets from peripheral blood, cord blood, thymus and spleen without prior expansion ex vivo, and identifying for the first time cytokines expressed by human NKT cells from spleen and thymus. Our comparative analysis reveals highly heterogeneous expression of surface antigens by CD4(+) and CD4(-) NKT cell subsets and identifies several antigens whose differential expression correlates with the cytokine response. Collectively, our findings reveal that the common classification of NKT cells into CD4(+) and CD4(-) subsets fails to reflect the diversity of this lineage, and that more studies are needed to establish the functional significance of the antigen expression patterns and tissue residency of human NKT cells.

The changing face of hepatitis in boys with haemophilia associated with increased prevalence of obesity

Hepatitis in children with haemophilia was historically most often associated with transfusion-transmitted infections. However, with the use of recombinant clotting factor concentrates, acquisition of such infections has now become rare. We studied the profile of hepatitis in North-American children with haemophilia in the modern era of safe blood products and excess childhood obesity. A total of 173 boys (<18 years) registered in the Pediatric Comprehensive Care Haemophilia Program were included in this retrospective study. Hospital records were reviewed for baseline data, serial height and weight measurements and serial alanine aminotransferase (ALT) levels. A body mass index (BMI) ranking was available for 170 boys, of whom 25 (14.7%, 95% CI 9.7-20.9%) were obese. The rate of obesity was higher in severe haemophilic boys. Compared with the general childhood population, the rate of obesity trended towards being higher in young haemophilic boys (2-5 years), but was similar in other age groups. A persistently high ALT (≥80 U L(-1) ) was documented in 5 boys and was associated with obesity. Three boys had clinical and imaging studies compatible with non-alcoholic fatty liver disease (NAFLD). Overweight and obesity are common among haemophilic boys, especially those who are younger and with severe disease. In this large group of haemophilic boys, chronic viral hepatitis was rare and NAFLD was a more common cause of liver disease. Overweight and obese haemophilic boys should be evaluated for NAFLD and interventional programmes should be designed to reduce the potential complications associated with obesity.

Acute humoral rejection in an ABO compatible combined liver-kidney transplant--the kidney is not always protected

Combined liver-kidney transplantation has become a common practice for the treatment of patients with concurrent end-stage renal disease and end-stage liver disease. Liver transplantation in the setting of multiorgan transplantation is thought to have a protective effect against humoral rejection even when a positive crossmatch is obtained prior to surgery. In most centers, a pre liver-kidney transplant crossmatch is rarely performed because of the known immunoprotective effect of the liver allograft. In this report, a case of acute humoral rejection in the kidney allograft after a combined liver-kidney transplant is described. Although humoral rejection was treated using plasmapheresis, intravenous immunoglobulin and rituximab, the kidney required 3 months to recover function and finally progressed to chronic allograft nephropathy. A heightened index of suspicion for acute humoral rejection of the renal allograft is necessary when performing combined liver-kidney transplants to highly sensitized patients due to previous organ transplants.

Viral fitness implications of variation within an immunodominant CD8+ T-cell epitope of HIV-1

Cytotoxic T-lymphocyte (CTL) epitopes within the HIV genome are subject to negative and positive selective pressures, the balance of which influences CTL escape at a given epitope. We investigated whether viral fitness requirements dictate conservation of the HLA-A2 restricted immunodominant epitope SLYNTVATL (SL9). Viral clones incorporating changes throughout the SL9 epitope region were compared to consensus SL9 virus in terms of replication kinetics and relative viral fitness. Constructs recapitulating in vivo SL9-CTL escape variants showed markedly little effect on replication and fitness, as did non-natural conservative mutations targeting immunologically relevant positions of the epitope. Although certain residues of the epitope were constrained by viral requirements, our research reveals that there are multiple SL9 variants that are well tolerated virologically but fail to arise in vivo. In light of this data, assumptions regarding the balance of immune and viral selective pressures on this immunodominant epitope sequence need to be reassessed.

Immune characterization of an individual with an exceptionally high natural killer T cell frequency and her immediate family

Natural killer T cells (NKT) are a regulatory subset of T lymphocytes whose frequency in peripheral blood is highly variable within the human population. Lower than normal NKT frequencies are associated with increased predisposition to a number of diseases, including type 1 diabetes and some forms of cancer, raising the possibility that an increased frequency may be protective. However, there is little or no understanding of how high NKT frequencies arise or, most importantly, whether the potential exists to boost and maintain NKT levels for therapeutic advantage. Here, we provide a detailed functional and phenotypic characterization of the NKT compartment of a human donor with NKT levels approximately 50 times greater than normal, including an analysis of NKT in her immediate family members. The study focuses upon the characteristics of this donor and her family, but demonstrates more broadly that the size and flexibility of the NKT niche is far greater than envisioned previously. This has important implications for understanding how the human NKT compartment is regulated, and supports the concept that the human NKT compartment might be expanded successfully for therapeutic benefit.

Use of modified U1 snRNAs to inhibit HIV-1 replication

Control of RNA processing plays a central role in regulating the replication of HIV-1, in particular the 3' polyadenylation of viral RNA. Based on the demonstration that polyadenylation of mRNAs can be disrupted by the targeted binding of modified U1 snRNA, we examined whether binding of U1 snRNAs to conserved 10 nt regions within the terminal exon of HIV-1 was able to inhibit viral structural protein expression. In this report, we demonstrate that U1 snRNAs complementary to 5 of the 15 regions targeted result in significant suppression of HIV-1 protein expression and viral replication coincident with loss of viral RNA. Suppression of viral gene expression is dependent upon appropriate assembly of a U1 snRNP particle as mutations of U1 snRNA that affect binding of U1 70K or Sm proteins significantly reduced efficacy. However, constructs lacking U1A binding sites retained significant anti-viral activity. This finding suggests a role for these mutants in situations where the wild-type constructs cause toxic effects. The conserved nature of the sequences targeted and the high efficacy of the constructs suggests that this strategy has significant potential as an HIV therapeutic.

Development of a foundation degree in health and social care

Health care in the UK is at present experiencing a shortfall of qualified health-care professionals. One initiative that has been proposed is to provide foundation degrees, which meet the needs of employers in a range of health and welfare settings and prepares students to support clients in maximizing their independence within a programme of care.

This article describes the development of the foundation degree in health and social care at the University of Central Lancashire, UK. A two-stage consultative exercise with practitioners was undertaken in the form of focus groups. These were multidisciplinary and grouped according to practice area. This form of consultation has enabled clinicians to feel valued for their skills and opinions and has ensured a curriculum that is relevant and current to the needs of practice.

Professional discourse and service cultures: an organisational typology developed from health and welfare services for people with learning disabilities

This study focuses upon the effect of social policy upon a particular area of service provision. It is influenced by the Foucauldian concept of governmentality and the proposition by Lewis et al. that social policy needs to be understood in local contexts. Only through understanding the partial and fragmented impact of policy can we gain a clear insight into the outcomes for users. The study is undertaken through an exploration of the micro politics of organisations providing health and welfare services for people with learning disabilities. It involves an approach to discourse analysis that focuses upon text developed from interviews with service providers, which is brought into contact with published literature in an iterative process. The interpretation of the text produces four themes: power, trust, citizenship and managerialism. The development of these themes and a further holistic interpretation of the text suggest an emerging organisational typology. A typology based upon different articulations of the themes noted that work to produce particular outcomes for service users.

Alterations in HIV-1 Rev transport in response to cell stress

Movement of HIV-1 Rev between the nucleus and cytoplasm is essential to its function. While normally nuclear, the protein can be induced to accumulate in the cytoplasm upon inhibition of RNA polymerase I/II. Nuclear accumulation of Rev in the presence of these inhibitors was found to be rescued upon addition of leptomycin B, an inhibitor of Rev nuclear export. This finding, in conjunction with kinetic data on nuclear import, indicates that the effect of the RNA polymerase inhibitors is due to an inversion of the rates of nuclear import versus export possibly achieved by increasing the rate of Rev nuclear export. We also examined whether changes in Rev localization could be due to a stress response. While neither ultraviolet radiation nor heat shock affected Rev subcellular localization, both oxidative and osmotic shocks induce changes in Rev localization comparable to that observed with the RNA polymerase inhibitors. The ability of certain serine/threonine kinase inhibitors, including CKI/II inhibitors, to cause cytoplasmic accumulation of Rev suggested that the alteration in Rev distribution could be due to changes in Rev or CRM1 phosphorylation. However, no change in extent of phosphorylation of either protein is observed upon treatment of cells with any of the agents tested, indicating involvement of another cellular factor.

The amino acid sequence of the PKR-eIF2alpha phosphorylation homology domain of hepatitis C virus envelope 2 protein and response to interferon-alpha

A region of the hepatitis C virus (HCV) envelope 2 protein, the protein kinase, PKR and early initiation factor 2alpha phosphorylation homology domain (PePHD), may be important in interferon (IFN)-alpha resistance. The PePHD was amplified by polymerase chain reaction and sequenced, and the amino acid sequence derived from pretreatment serum of 14 genotype 3-infected patients with a range of responses to IFN-alpha therapy. Only 1 patient had a PePHD variant. IFN-resistant PePHD variants present at low titers in pretreatment serum should be selected by therapy; therefore, the PePHD amino acid sequence was also obtained from serum collected during or after treatment in 5 patients with breakthrough or relapse of HCV RNA positivity. No difference was found between the pre- and posttreatment PePHD sequences. Thus, it appears that pretreatment sequencing of the PePHD would not enable clinicians to predict the treatment response. There was no evidence that IFN therapy exerts selection pressure in this region.

Both beta(2)- and beta(1)-adrenergic receptors mediate hastened relaxation and phosphorylation of phospholamban and troponin I in ventricular myocardium of Fallot infants, consistent with selective coupling of beta(2)-adrenergic receptors to G(s)-protein

BACKGROUND

In adult human heart, both beta(1)- and beta(2)-adrenergic receptors mediate hastening of relaxation; however, it is unknown whether this also occurs in infant heart. We compared the effects of stimulation of beta(1)- and beta(2)-adrenergic receptors on relaxation and phosphorylation of phospholamban and troponin I in ventricle obtained from infants with tetralogy of Fallot.

METHODS AND RESULTS

Myocardium dissected from the right ventricular outflow tract of 27 infants (age range 21/2 to 35 months) with tetralogy of Fallot was set up to contract 60 times per minute. Selective stimulation of beta(1)-adrenergic receptors with (-)-norepinephrine (NE) and beta(2)-adrenergic receptors with (-)-epinephrine (EPI) evoked phosphorylation of phospholamban (at serine-16 and threonine-17) and troponin I and caused concentration-dependent increases in contractile force (-log EC(50) [mol/L] NE 5.5+/-0.1, n=12; EPI 5.6+/-0.1, n=13 patients), hastening of the time to reach peak force (-log EC(50) [mol/L] NE 5.8+/-0.2; EPI 5.8+/-0.2) and 50% relaxation (-log EC(50) [mol/L] NE 5.7+/-0.2; EPI 5.8+/-0.1). Ventricular membranes from Fallot infants, labeled with (-)-[(125)I]-cyanopindolol, revealed a greater percentage of beta(1)- (71%) than beta(2)-adrenergic receptors (29%). Binding of (-)-epinephrine to beta(2)-receptors underwent greater GTP shifts than binding of (-)-norepinephrine to beta(1)-receptors.

CONCLUSIONS

Despite their low density, beta(2)-adrenergic receptors are nearly as effective as beta(1)-adrenergic receptors of infant Fallot ventricle in enhancing contraction, relaxation, and phosphorylation of phospholamban and troponin I, consistent with selective coupling to G(s)-protein.

Common pulmonary vein atresia: a diagnostic and therapeutic challenge

Following Doppler echocardiographic evaluation, a 16 hour-old infant underwent successful surgical repair of common pulmonary vein atresia. Investigations for prolonged postoperative ventilatory assistance, including cardiac catheterization and computerized tomography, led to a clinical diagnosis of associated pulmonary lymphangiectasia. Although this has caused continuing tachypnoea, at 16 months of age, he remains otherwise well but with an uncertain prognosis.

Regulated expression of HIV-1 Rev function in mammalian cell lines

In order to facilitate further investigation of Rev function, we have generated two systems for the inducible expression of Rev in mammalian cell lines (HeLa and U937) using either a tetracycline-regulated promoter or fusion of Rev to a modified form of the hormone binding domain of the estrogen receptor. In the case of the fusion of Rev to the modified hormone binding domain of the estrogen receptor, we demonstrated induction of Rev function in response to tamoxifen administration to levels comparable to that of the unmodified Rev protein. Subsequently, U937 lines were generated that retained the observed pattern of hormone-dependent function of the Rev fusion protein. In the case of the tetracycline-regulated system, cell lines (both HeLa and U937) were generated that displayed tight regulation of Rev. In the case of the HeLa cell lines, they were used for the subsequent generation of stable cell lines expressing either HIV-1 env or chloramphenicol acetyl transferase (CAT) in a Rev-dependent fashion. Using the latter cell lines, we demonstrate the ability to control Rev expression over a broad concentration range and find that, as soon as Rev expression is detectable, induction of Rev-dependent gene expression is also observed.

Control of human immunodeficiency virus type 1 RNA metabolism: role of splice sites and intron sequences in unspliced viral RNA subcellular distribution

In the course of examining the various factors which affect the metabolism of human immunodeficiency virus type 1 (HIV-1) RNA, we examined the role of intron sequences and splice sites in determining the subcellular distribution of the RNA. Using in situ hybridization, we demonstrated that in the absence of Rev, unspliced RNA generated with an HIV-1 env expression construct displayed discrete localization in the nucleus, coincident with the location of the gene and not associated with SC35-containing nuclear speckles. Expression of Rev resulted in a disperse signal for the unspliced RNA throughout both the nucleus and the cytoplasm. Subsequent fractionation of the nucleus revealed that the majority of unspliced viral RNA within the nucleus is associated with the nuclear matrix and that upon expression of Rev, a small proportion of the unspliced RNA is found within the nucleoplasm. Mutations which altered splice site utilization did not alter the sequestration of unspliced RNA into discrete nuclear regions. In contrast, a 2.2-kb deletion of intron sequence resulted in a shift from discrete regions within the nucleus to a disperse signal throughout the cell, indicating that intron sequences, and not just splice sites, are required for the observed nuclear sequestration of unspliced viral RNA.

Novel exonic elements that modulate splicing of the human fibronectin EDA exon

Three exons in the fibronectin primary transcript are alternatively spliced in a tissue- and developmental stage-specific manner. One of these exons, EDA, has been shown previously by others to contain two splicing regulatory elements between 155 and 180 nucleotides downstream of the 3'-splice site: an exon splicing enhancer and a negative element. By transient expression of a chimeric beta-globin/fibronectin EDA intron in COS-7 cells, we have identified two additional exonic splicing regulatory elements. RNA generated by a construct containing the first 120 nucleotides of the fibronectin EDA exon was spliced with an efficiency of approximately 50%. Deletion of most of the fibronectin EDA exon sequences resulted in a 20-fold increase in the amount of spliced RNA, indicative of an exon splicing silencer. Deletion and mutagenesis studies suggest that the fibronectin exon splicing silencer is associated with a conserved RNA secondary structure. In addition, sequences between nucleotides 93 and 118 of the EDA exon contain a non-purine-rich splicing enhancer as demonstrated by its ability to function in a heterologous context.

Cyclic-AMP modulates downstream events in CD40-mediated signal transduction, but inhibition of protein kinase A has no direct effect on CD40 signaling

The role of cAMP/protein kinase A (PKA) in CD40 signal transduction is controversial, with evidence both for and against its importance. In this study we have used a tetracycline-repressible expression system to reversibly express a dominant-negative form of the PKA regulatory subunit type I (PKA-R(G324D)) in a B lymphoma line, M12. Expression of PKA-R(G324D) in M12 lymphomas inhibits both cAMP-mediated growth inhibition and cAMP-mediated induction of B7-2. This inhibition is reversed by tetracycline treatment of the cells to turn off inhibitor expression. In contrast, the expression of the PKA-R(G324D) subunit has no effect on CD40-mediated growth inhibition in M12 cells, nor on CD40-mediated induction of B7-1, CD23, Fas, ICAM-1, or LFA-1. Thus, our data do not support a direct role for cAMP/PKA in CD40-mediated signal transduction. However, we do observe that cAMP can regulate CD40 signaling both positively and negatively. Cyclic-AMP synergizes with CD40-mediated B7-1 induction in M12 lymphomas, while inhibiting CD40-mediated CD23, Fas, and ICAM-1 induction.