Obesity Impairs Lymphatic Fluid Transport and Dendritic Cell Migration to Lymph Nodes

Introduction

Obesity is a major cause of morbidity and mortality resulting in pathologic changes in virtually every organ system. Although the cardiovascular system has been a focus of intense study, the effects of obesity on the lymphatic system remain essentially unknown. The purpose of this study was to identify the pathologic consequences of diet induced obesity (DIO) on the lymphatic system.

Methods

Adult male wild-type or RAG C57B6-6J mice were fed a high fat (60%) or normal chow diet for 8–10 weeks followed by analysis of lymphatic transport capacity. In addition, we assessed migration of dendritic cells (DCs) to local lymph nodes, lymph node architecture, and lymph node cellular make up.

Results

High fat diet resulted in obesity in both wild-type and RAG mice and significantly impaired lymphatic fluid transport and lymph node uptake; interestingly, obese wild-type but not obese RAG mice had significantly impaired migration of DCs to the peripheral lymph nodes. Obesity also resulted in significant changes in the macro and microscopic anatomy of lymph nodes as reflected by a marked decrease in size of inguinal lymph nodes (3.4-fold), decreased number of lymph node lymphatics (1.6-fold), loss of follicular pattern of B cells, and dysregulation of CCL21 expression gradients. Finally, obesity resulted in a significant decrease in the number of lymph node T cells and increased number of B cells and macrophages.

Conclusions

Obesity has significant negative effects on lymphatic transport, DC cell migration, and lymph node architecture. Loss of T and B cell inflammatory reactions does not protect from impaired lymphatic fluid transport but preserves DC migration capacity. Future studies are needed to determine how the interplay between diet, obesity, and the lymphatic system modulate systemic complications of obesity.     

Combining Surveillance Systems: Effective Merging of U.S. Veteran and Military Health Data

Background

The U.S. Department of Veterans Affairs (VA) and Department of Defense (DoD) had more than 18 million healthcare beneficiaries in 2011. Both Departments conduct individual surveillance for disease events and health threats.

Methods

We performed joint and separate analyses of VA and DoD outpatient visit data from October 2006 through September 2010 to demonstrate geographic and demographic coverage, timeliness of influenza epidemic awareness, and impact on spatial cluster detection achieved from a joint VA and DoD biosurveillance platform.

Results

Although VA coverage is greater, DoD visit volume is comparable or greater. Detection of outbreaks was better in DoD data for 58% and 75% of geographic areas surveyed for seasonal and pandemic influenza, respectively, and better in VA data for 34% and 15%. The VA system tended to alert earlier with a typical H3N2 seasonal influenza affecting older patients, and the DoD performed better during the H1N1 pandemic which affected younger patients more than normal influenza seasons. Retrospective analysis of known outbreaks demonstrated clustering evidence found in separate DoD and VA runs, which persisted with combined data sets.

Conclusion

The analyses demonstrate two complementary surveillance systems with evident benefits for the national health picture. Relative timeliness of reporting could be improved in 92% of geographic areas with access to both systems, and more information provided in areas where only one type of facility exists. Combining DoD and VA data enhances geographic cluster detection capability without loss of sensitivity to events isolated in either population and has a manageable effect on customary alert rates.     

Discovery of a Mammalian Splice Variant of Myostatin That Stimulates Myogenesis

Myostatin plays a fundamental role in regulating the size of skeletal muscles. To date, only a single myostatin gene and no splice variants have been identified in mammals. Here we describe the splicing of a cryptic intron that removes the coding sequence for the receptor binding moiety of sheep myostatin. The deduced polypeptide sequence of the myostatin splice variant (MSV) contains a 256 amino acid N-terminal domain, which is common to myostatin, and a unique C-terminus of 65 amino acids. Western immunoblotting demonstrated that MSV mRNA is translated into protein, which is present in skeletal muscles. To determine the biological role of MSV, we developed an MSV over-expressing C₂C₁₂ myoblast line and showed that it proliferated faster than that of the control line in association with an increased abundance of the CDK2/Cyclin E complex in the nucleus. Recombinant protein made for the novel C-terminus of MSV also stimulated myoblast proliferation and bound to myostatin with high affinity as determined by surface plasmon resonance assay. Therefore, we postulated that MSV functions as a binding protein and antagonist of myostatin. Consistent with our postulate, myostatin protein was co-immunoprecipitated from skeletal muscle extracts with an MSV-specific antibody. MSV over-expression in C₂C₁₂ myoblasts blocked myostatin-induced Smad2/3-dependent signaling, thereby confirming that MSV antagonizes the canonical myostatin pathway. Furthermore, MSV over-expression increased the abundance of MyoD, Myogenin and MRF4 proteins (P<0.05), which indicates that MSV stimulates myogenesis through the induction of myogenic regulatory factors. To help elucidate a possible role in vivo, we observed that MSV protein was more abundant during early post-natal muscle development, while myostatin remained unchanged, which suggests that MSV may promote the growth of skeletal muscles. We conclude that MSV represents a unique example of intra-genic regulation in which a splice variant directly antagonizes the biological activity of the canonical gene product.     

Replication in hydroxyurea: it's a matter of time

Hydroxyurea (HU) is a DNA replication inhibitor that negatively affects both the elongation and initiation phases of replication and triggers the "intra-S phase checkpoint." Previous work with budding yeast has shown that, during a short exposure to HU, MEC1/RAD53 prevent initiation at some late S phase origins. In this study, we have performed microarray experiments to follow the fate of all origins over an extended exposure to HU. We show that the genome-wide progression of DNA synthesis, including origin activation, follows the same pattern in the presence of HU as in its absence, although the time frames are very different. We find no evidence for a specific effect that excludes initiation from late origins. Rather, HU causes S phase to proceed in slow motion; all temporal classes of origins are affected, but the order in which they become active is maintained. We propose a revised model for the checkpoint response to HU that accounts for the continued but slowed pace of the temporal program of origin activation.     

Calcium release by ryanodine receptors mediates hydrogen peroxide-induced activation of ERK and CREB phosphorylation in N2a cells and hippocampal neurons

Hydrogen peroxide, which stimulates ERK phosphorylation and synaptic plasticity in hippocampal neurons, has also been shown to stimulate calcium release in muscle cells by promoting ryanodine receptor redox modification (S-glutathionylation). We report here that exposure of N2a cells or rat hippocampal neurons in culture to 200 microM H2O2 elicited calcium signals, increased ryanodine receptor S-glutathionylation, and enhanced both ERK and CREB phosphorylation. In mouse hippocampal slices, H2O2 (1 microM) also stimulated ERK and CREB phosphorylation. Preincubation with ryanodine (50 microM) largely prevented the effects of H2O2 on calcium signals and ERK/CREB phosphorylation. In N2a cells, the ERK kinase inhibitor U0126 suppressed ERK phosphorylation and abolished the stimulation of CREB phosphorylation produced by H2O2, suggesting that H2O2 enhanced CREB phosphorylation via ERK activation. In N2a cells in calcium-free media, 200 microM H2O2 stimulated ERK and CREB phosphorylation, while preincubation with thapsigargin prevented these enhancements. These combined results strongly suggest that H2O2 promotes ryanodine receptors redox modification; the resulting calcium release signals, by enhancing ERK activity, would increase CREB phosphorylation. We propose that ryanodine receptor stimulation by activity-generated redox species produces calcium release signals that may contribute significantly to hippocampal synaptic plasticity, including plasticity that requires long-lasting ERK-dependent CREB phosphorylation.     

Parental intention to have daughters receive the human papillomavirus vaccine

Background

Concerns have been raised that parents may be reluctant to have their daughters receive the human papillomavirus (HPV) vaccine, because of a belief that doing so might be interpreted as condoning earlier and more frequent sexual activity. We determined intentions regarding vaccination among Canadian parents and factors that predicted parental intention to have their daughters vaccinated against HPV.

Methods

Parents of children 8–18 years of age, recruited from across Canada, were asked to respond to questions in the context of a grade 6, publicly funded, school-based HPV vaccine program. We performed backward logistic regression analysis to identify factors predictive of parents'' intention to have their daughters vaccinated against HPV.

Results

Of the 1350 respondents with female children, more than 70% (73.8%; 95% confidence interval [CI] 71.5%– 76.1%) intended to have their daughters undergo vaccination against HPV. In multivariable modelling, parents who had positive attitudes toward vaccines (odds ratio [OR] 9.9, 95% CI 4.7–21.1), those who were influenced by subjective norms (OR 9.2, 95% CI 6.6–12.9), those who felt that the vaccine had limited influence on sexual behaviour (OR 3.2, 95% CI 2.2–4.6) and those who thought someone they knew was likely to get cervical cancer (OR 1.5, 95% CI 1.1–2.1) were more likely to intend that their daughters receive the HPV vaccine. Parents who were older (v. younger) (OR 0.6, 95% CI 0.4–0.8) and those who resided in British Columbia or Yukon Territory (v. Atlantic Canada) (OR 0.5, 95% CI 0.3–0.9) were less likely to intend that their daughters receive the HPV vaccine.

Interpretation

Most of the parents surveyed intended that their daughters would receive vaccination against HPV. Overall attitudes toward vaccines in general and toward the HPV vaccine in particular constituted the most significant predictor of parental intention with regard to vaccination.The vaccine against the human papillomavirus (HPV) represents a major step toward the prevention of cervical cancer.^1,2 HPV is a sexually acquired virus, and mathematical modelling and economic analyses have demonstrated that the vaccine''s maximum benefit in terms of preventing cervical cancer is achieved when vaccination programs target female and possibly male adolescents before their sexual debut, likely before the age of 12 years.³ The clinical efficacy and safety of the currently available HPV vaccine have been established,⁴ but concerns have been raised that parents may be reluctant to have their children undergo vaccination at this age, because of a belief that doing so might be interpreted to mean that they are condoning or even promoting earlier and more frequent sexual activity. Since parental attitudes play a crucial role in vaccination uptake and can provide direction for messaging and education in support of vaccination uptake,⁵ we sought to determine parental intentions to have daughters vaccinated against HPV and the factors that predict those intentions.     

c9,t11-Conjugated linoleic acid ameliorates steatosis by modulating mitochondrial uncoupling and Nrf2 pathway

Oxidative stress, hepatic steatosis, and mitochondrial dysfunction are key pathophysiological features of nonalcoholic fatty liver disease. A conjugated linoleic acid (CLA) mixture of cis9,trans11 (9,11-CLA) and trans10,cis12 (10,12-CLA) isomers enhanced the antioxidant/detoxifying mechanism via the activation of nuclear factor E2-related factor-2 (Nrf2) and improved mitochondrial function, but less is known about the actions of specific isomers. The differential ability of individual CLA isomers to modulate these pathways was explored in Wistar rats fed for 4 weeks with a lard-based high-fat diet (L) or with control diet (CD), and, within each dietary treatment, two subgroups were daily administered with 9,11-CLA or 10,12-CLA (30 mg/day). The 9,11-CLA, but not 10,12-CLA, supplementation to CD rats improves the GSH/GSSG ratio in the liver, mitochondrial functions, and Nrf2 activity. Histological examination reveals a reduction of steatosis in L-fed rats supplemented with both CLA isomers, but 9,11-CLA downregulated plasma concentrations of proinflammatory markers, mitochondrial dysfunction, and oxidative stress markers in liver more efficiently than in 10,12-CLA treatment. The present study demonstrates the higher protective effect of 9,11-CLA against diet-induced pro-oxidant and proinflammatory signs and suggests that these effects are determined, at least in part, by its ability to activate the Nrf2 pathway and to improve the mitochondrial functioning and biogenesis.     

Molecular diversity of bacterial communities from subseafloor rock samples in a deep-water production basin in Brazil

The deep subseafloor rock in oil reservoirs represents a unique environment in which a high oilcontamination and very low biomass can be observed. Sampling this environment has been a challenge owing to the techniques used for drilling and coring. In this study, the facilities developed by the Brazilian oil company PETROBRAS for accessing deep subsurface oil reservoirs were used to obtain rock samples at 2,822-2,828 m below the ocean floor surface from a virgin field located in the Atlantic Ocean, Rio de Janeiro. To address the bacterial diversity of these rock samples, PCR amplicons were obtained using the DNA from four core sections and universal primers for 16S rRNA and for APS reductase (aps) genes. Clone libraries were generated from these PCR fragments and 87 clones were sequenced. The phylogenetic analyses of the 16S rDNA clone libraries showed a wide distribution of types in the domain bacteria in the four core samples, and the majority of the clones were identified as belonging to Betaproteobacteria. The sulfate-reducing bacteria community could only be amplified by PCR in one sample, and all clones were identified as belonging to Gammaproteobacteria. For the first time, the bacterial community was assessed in such deep subsurface environment.