bluuebunny/crossref_metadata_2025 huggingface dataset:
HIV testing in colposcopy and termination of pregnancy services: a missed opportunity?
Authors: Briggs Aparna , Partridge David G , Bates Sylvia
Published: August 2011

Introduction

The 2008 National HIV testing guidelines produced jointly by the British Association of Sexual Health and HIV, British HIV Association and British Infection Society recommend HIV testing for patients attending termination of pregnancy (TOP) services and patients diagnosed with cervical intraepithelial neoplasia (CIN) Grade 2 or above. The aim is to reduce the time between acquisition and diagnosis of HIV by encouraging testing in settings where patients present with indicator diseases. Benefits of earlier HIV diagnosis include improved survival, prevention of onward transmission, and optimisation of maternal health when planning pregnancy. There is evidence that HIV reduces the effectiveness of standard treatment for CIN 2/3 and cervical cancer. The experience of antenatal screening indicates that the majority of women accept HIV screening if it is offered as part of a package of care.

Methods

This retrospective case notes review of 60 HIV-positive women, diagnosed between 1 January 2006 and 31 July 2009, collected data on age, ethnicity, length of time in the UK, timing of HIV diagnosis and possible timing of acquisition relative to attendance at colposcopy or TOP services, CD4 count and symptoms at diagnosis and cervical cytology history.

Results

The authors found that three (5%) women were diagnosed with CIN Grade 2 or above prior to HIV diagnosis; HIV testing at the time of TOP may have resulted in earlier diagnosis for three (5%) women. There was at least one missed opportunity for earlier diagnosis in five (8%) cases.

Conclusions

The authors suggest further work should be undertaken to establish HIV prevalence in TOP and colposcopy services and that HIV testing should become standard practice in the management of CIN 2/3 and cervical cancer.
STOKER'S THEOREM FOR ORTHOGONAL POLYHEDRA
Authors: BIEDL THERESE , GENÇ BURKAY
Published: August 2011

Stoker's theorem states that in a convex polyhedron, the dihedral angles and edge lengths determine the facial angles if the graph is fixed. In this paper, we study under what conditions Stoker's theorem holds for orthogonal polyhedra, obtaining uniqueness and a linear-time algorithm in some cases, and NP-hardness in others.
SIMPLIPOLY: CURVATURE-BASED POLYGONAL CURVE SIMPLIFICATION
Authors: CHUON CHANSOPHEA , GUHA SUMANTA , JANECEK PAUL , SONG NGUYEN DUC CONG
Published: August 2011

A curvature-based algorithm to simplify a polygonal curve is described, together with its implementation. The so-called SimpliPoly algorithm uses Bézier curves to approximate pieces of the input curve, and assign curvature estimates to vertices of the input polyline from curvature values computed for the Bézier approximations. The authors' implementation of SimpliPoly is interactive and available freely on-line. Additionally, a third-party implementation of SimpliPoly as a plug-in for the GNU Blender 3D modeling software is available. Empirical comparisons indicate that SimpliPoly performs as well as the widely-used Douglas-Peucker algorithm in most situations, and significantly better, because it is curvature-driven, in applications where it is necessary to preserve local features.
POPULATION DYNAMICS ON COMPLEX FOOD WEBS
Authors: PALAMARA GIAN MARCO , ZLATIĆ VINKO , SCALA ANTONIO , CALDARELLI GUIDO
Published: August 2011

In this work we analyze the topological and dynamical properties of a simple model of complex food webs, namely the niche model. In order to underline competition among species, we introduce "prey" and "predators" weighted overlap graphs derived from the niche model and compare synthetic food webs with real data. Doing so, we find new tests for the goodness of synthetic food web models and indicate a possible direction of improvement for existing ones. We then exploit the weighted overlap graphs to define a competition kernel for Lotka–Volterra population dynamics and find that for such a model the stability of food webs decreases with its ecological complexity.
MODELING SETTLEMENT PATTERNS IN REAL TERRITORIES
Authors: CARVALHO JOAQUIM , LOPES RUI L. , TOJO JOÃO
Published: August 2011

This paper, describes an agent based model of the spreading of a population over a territory. The models aims at reproducing a distribution of settlements with statistical and spatial characteristics similar to a historically produced pattern. The model operates on a representation of a real territory, taking into account hydrography and relief. The two main goals are to obtain a rank size distribution of the size of settlements which corresponds to a power law (also known as the Zipf Law of settlements) and to place the settlements in the territory in patterns that are close to the real ones, in zones where settlements were the result of a long historical process. The goal of the project was to demonstrate that a set of relatively simple rules could produce a complex pattern, similar to the result of a long and complex historical process. Therefore, it is an assumed reductionist approach.

Our conclusions show that a simple territorial logic, taking into account the quality of land, accessibility, population growth and migration preferences could reproduce Zipf distributions and interesting patterns of agent flow among the settlements created. However, achieving spatial patterns closer to the historical record needs an extra dimension involving field of sight. The best results were achieved by creating an artifical population which chooses to create settlements in places where a wide field of view exists of quality territory.
On the origin of rhythmic calcium transients in the ICC-MP of the mouse small intestine
Authors: Lowie Bobbi-Jo , Wang Xuan-Yu , White Elizabeth J. , Huizinga Jan D.
Published: August 2011

Interstitial cells of Cajal associated with the myenteric plexus (ICC-MP) are pacemaker cells of the small intestine, producing the characteristic omnipresent electrical slow waves, which orchestrate peristaltic motor activity and are associated with rhythmic intracellular calcium oscillations. Our objective was to elucidate the origins of the calcium transients. We hypothesized that calcium oscillations in the ICC-MP are primarily regulated by the sarcoplasmic reticulum (SR) calcium release system. With the use of calcium imaging, study of the effect of T-type calcium channel blocker mibefradil revealed that T-type channels did not play a major role in generating the calcium transients. 2-Aminoethoxydiphenyl borate, an inositol 1,4,5 trisphosphate receptor (IP3R) inhibitor, and U73122, a phospholipase C inhibitor, both drastically decreased the frequency of calcium oscillations, suggesting a major role of IP3and IP3-induced calcium release from the SR. Immunohistochemistry proved the expression of IP3R type I (IP3R-I), but not type II (IP3R-II) and type III (IP3R-III) in ICC-MP, indicating the involvement of the IP3R-I subtype in calcium release from the SR. Cyclopiazonic acid, a SR/endoplasmic reticulum calcium ATPase pump inhibitor, strongly reduced or abolished calcium oscillations. The Na-Ca exchanger (NCX) in reverse mode is likely involved in refilling the SR because the NCX inhibitor KB-R7943 markedly reduced the frequency of calcium oscillations. Immunohistochemistry revealed 100% colocalization of NCX and c-Kit in ICC-MP. Testing a mitochondrial NCX inhibitor, we were unable to show an essential role for mitochondria in regulating calcium oscillations in the ICC-MP. In summary, ongoing IP3synthesis and IP3-induced calcium release from the SR, via the IP3R-I, are the major drivers of the calcium transients associated with ICC pacemaker activity. This suggests that a biochemical clock intrinsic to ICC determines the pacemaker frequency, which is likely directly linked to kinetics of the IP3-activated SR calcium channel and IP3metabolism.
Intestinal epithelial-specific PTEN inactivation results in tumor formation
Authors: Byun Do-Sun , Ahmed Naseem , Nasser Shannon , Shin Joongho , Al-Obaidi Sheren , Goel Sanjay , Corner Georgia A. , Wilson Andrew J. , Flanagan Dustin J. , Williams David S. , Augenlicht Leonard H. , Vincan Elizabeth , Mariadason John M.
Published: August 2011

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a negative regulator of phosphatidylinositol 3-kinase (PI3K) signaling that is frequently inactivated in colorectal cancer through mutation, loss of heterozygosity, or epigenetic mechanisms. The aim of this study was to determine the effect of intestinal-specific PTEN inactivation on intestinal epithelial homeostasis and tumorigenesis. PTEN was deleted specifically in the intestinal epithelium, by crossing PTEN Lox/ Lox mice with villin Cre mice. PTEN was robustly expressed in the intestinal epithelium and maximally in the differentiated cell compartment. Targeted inactivation of PTEN in the intestinal epithelium of PTEN Lox/ Lox/villin Cre mice was confirmed by genotyping, immunohistochemistry, and qPCR. While intestinal-specific PTEN deletion did not have a major effect on cell fate determination or proliferation in the small intestine, it did increase phosphorylated (p) protein kinase B (AKT) expression in the intestinal epithelium, and 19% of animals developed small intestinal adenomas and adenocarcinomas at 12 mo of age. These tumors demonstrated pAKT and nuclear β-catenin staining, indicating simultaneous activation of the PI3K/AKT and Wnt signaling pathways. These findings demonstrate that, while PTEN inactivation alone has a minimal effect on intestinal homeostasis, it can facilitate tumor promotion upon deregulation of β-catenin/TCF signaling, further establishing PTEN as a bona fide tumor suppressor gene in intestinal cancer.
Cardiovascular regulation by skeletal muscle reflexes in health and disease
Authors: Murphy Megan N. , Mizuno Masaki , Mitchell Jere H. , Smith Scott A.
Published: August 2011

Heart rate and blood pressure are elevated at the onset and throughout the duration of dynamic or static exercise. These neurally mediated cardiovascular adjustments to physical activity are regulated, in part, by a peripheral reflex originating in contracting skeletal muscle termed the exercise pressor reflex. Mechanically sensitive and metabolically sensitive receptors activating the exercise pressor reflex are located on the unencapsulated nerve terminals of group III and group IV afferent sensory neurons, respectively. Mechanoreceptors are stimulated by the physical distortion of their receptive fields during muscle contraction and can be sensitized by the production of metabolites generated by working skeletal myocytes. The chemical by-products of muscle contraction also stimulate metaboreceptors. Once activated, group III and IV sensory impulses are transmitted to cardiovascular control centers within the brain stem where they are integrated and processed. Activation of the reflex results in an increase in efferent sympathetic nerve activity and a withdrawal of parasympathetic nerve activity. These actions result in the precise alterations in cardiovascular hemodynamics requisite to meet the metabolic demands of working skeletal muscle. Coordinated activity by this reflex is altered after the development of cardiovascular disease, generating exaggerated increases in sympathetic nerve activity, blood pressure, heart rate, and vascular resistance. The basic components and operational characteristics of the reflex, the techniques used in human and animals to study the reflex, and the emerging evidence describing the dysfunction of the reflex with the advent of cardiovascular disease are highlighted in this review.
Persistent pulmonary hypertension results in reduced tetralinoleoyl-cardiolipin and mitochondrial complex II + III during the development of right ventricular hypertrophy in the neonatal pig heart
Authors: Saini-Chohan Harjot K. , Dakshinamurti Shyamala , Taylor William A. , Shen Garry X. , Murphy Robert , Sparagna Genevieve C. , Hatch Grant M.
Published: August 2011

Persistent pulmonary hypertension of the newborn (PPHN) results in right ventricular (RV) hypertrophy followed by right heart failure and an associated mitochondrial dysfunction. The phospholipid cardiolipin plays a key role in maintaining mitochondrial respiratory and cardiac function via modulation of the activities of enzymes involved in oxidative phosphorylation. In this study, changes in cardiolipin and cardiolipin metabolism were investigated during the development of right heart failure. Newborn piglets (<24 h old) were exposed to a hypoxic (10% O2) environment for 3 days, resulting in the induction of PPHN. Two sets of control piglets were used: 1) newborn or 2) exposed to a normoxic (21% O2) environment for 3 days. Cardiolipin biosynthetic and remodeling enzymes, mitochondrial complex II + III activity, incorporation of [1-14C]linoleoyl-CoA into cardiolipin precursors, and the tetralinoleoyl-cardiolipin pool size were determined in both the RV and left ventricle (LV). PPHN resulted in an increased heart-to-body weight ratio, RV-to-LV plus septum weight ratio, and expression of brain naturetic peptide in RV. In addition, PPHN reduced cardiolipin biosynthesis and remodeling in the RV and LV, which resulted in decreased tetralinoleoyl-cardiolipin levels and reduced complex II + III activity and protein levels of mitochondrial complexes II, III, and IV in the RV. This is the first study to examine the pattern of cardiolipin metabolism during the early development of both the RV and LV of the newborn piglet and to demonstrate that PPHN-induced alterations in cardiolipin biosynthetic and remodeling enzymes contribute to reduced tetralinoleoyl-cardiolipin and mitochondrial respiratory chain function during the development of RV hypertrophy. These defects in cardiolipin may play an important role in the rapid development of RV dysfunction and right heart failure in PPHN.
Myristoylated methionine sulfoxide reductase A protects the heart from ischemia-reperfusion injury
Authors: Zhao Hang , Sun Junhui , Deschamps Anne M. , Kim Geumsoo , Liu Chengyu , Murphy Elizabeth , Levine Rodney L.
Published: August 2011

Methionine sulfoxide reductase A (MsrA) catalytically scavenges reactive oxygen species and also repairs oxidized methionines in proteins. Increasing MsrA protects cells and organs from a variety of oxidative stresses while decreasing MsrA enhances damage, but the mechanisms of action have not been elucidated. A single gene encodes MsrA of which ∼25% is targeted to the mitochondria, a major site of reactive oxygen species production. The other ∼75% is targeted to the cytosol and is posttranslationally modified by myristoylation. To determine the relative importance of MsrA in each compartment in protecting against ischemia-reperfusion damage, we created a series of transgenic mice overexpressing MsrA targeted to the mitochondria or the cytosol. We used a Langendorff model of ischemia-reperfusion and assayed both the rate pressure product and infarct size following ischemia and reperfusion as measures of injury. While the mitochondrially targeted MsrA was expected to be protective, it was not. Notably, the cytosolic form was protective but only if myristoylated. The nonmyristoylated, cytosolic form offered no protection against injury. We conclude that cytosolic MsrA protects the heart from ischemia-reperfusion damage. The requirement for myristoylation suggests that MsrA must interact with a hydrophobic domain to provide protection.
Carotid baroreflex responsiveness is impaired in normotensive African American men
Authors: Holwerda Seth W. , Fulton Diana , Eubank Wendy L. , Keller David M.
Published: August 2011

There are important differences in autonomic function and cardiovascular responsiveness between African Americans (AA) and Caucasian Americans (CA). This study tested the hypothesis that carotid baroreflex (CBR) responsiveness is impaired in normotensive AA compared with normotensive CA at rest. CBR control of heart rate (HR) and mean arterial blood pressure (MAP) was assessed in 30 nonhypertensive male subjects (15 AA; 15 CA; age 18–33 yr) with 5-s periods of neck pressure (NP; simulated hypotension) and neck suction (NS; simulated hypertension) ranging from +45 to −80 Torr during rest. Carotid-cardiac stimulus-response curves revealed a significantly lower minimum HR response in the CA compared with AA (40.8 ± 2.4 vs. 49.8 ± 2.9 beats/min, respectively; P < 0.05). In addition, the magnitude of the mean HR response to all trials of NS (−20, −40, −60, and −80 Torr) was attenuated in the AA group (AA, −10.1 ± 1.7 vs. CA, −14.9 ± 2.2 beats/min; P < 0.05), while no significant differences were found in the magnitude of the mean HR response to NP (+15, +30, and +45 Torr) between racial groups. There were no significant differences in the carotid-vasomotor stimulus-response curves between racial groups. Also, while no racial differences were found in the magnitude of the mean MAP response to all trials of NS, the magnitude of the mean MAP response to all trials of NP was attenuated in the AA group (AA, 7.2 ± 1.3 vs. CA, 9.3 ± 1.1 mmHg; P < 0.05). Together, these findings support inherent differences in short-term blood pressure regulation between racial groups that exhibit different relative risk for the development of hypertension.
Low-intensity interval exercise training attenuates coronary vascular dysfunction and preserves Ca2+-sensitive K+ current in miniature swine with LV hypertrophy
Authors: Emter Craig A. , Tharp Darla L. , Ivey Jan R. , Ganjam Venkataseshu K. , Bowles Douglas K.
Published: August 2011

Coronary vascular dysfunction has been observed in several models of heart failure (HF). Recent evidence indicates that exercise training is beneficial for patients with HF, but the precise intensity and underlying mechanisms are unknown. Left ventricular (LV) hypertrophy can play a significant role in the development of HF; therefore, the purpose of this study was to assess the effects of low-intensity interval exercise training on coronary vascular function in sedentary (HF) and exercise trained (HF-TR) aortic-banded miniature swine displaying LV hypertrophy. Six months postsurgery, in vivo coronary vascular responses to endothelin-1 (ET-1) and adenosine were measured in the left anterior descending coronary artery. Baseline and maximal coronary vascular conductance were similar between all groups. ET-1-induced reductions in coronary vascular conductance ( P < 0.05) were greater in HF vs. sedentary control and HF-TR groups. Pretreatment with the ET type A (ETA) receptor blocker BQ-123 prevented ET-1 hypersensitivity in HF animals. Whole cell voltage clamp was used to characterize composite K+ currents ( IK+) in coronary smooth muscle cells. Raising internal Ca2+ from 200 to 500 nM increased Ca2+-sensitive K+ current in HF-TR and control, but not HF animals. In conclusion, an ETA-receptor-mediated hypersensitivity to ET-1, elevated resting LV wall tension, and decreased coronary smooth muscle cell Ca2+-sensitive IK+ was found in sedentary animals with LV hypertrophy. Low-intensity interval exercise training preserved normal coronary vascular function and smooth muscle cell Ca2+-sensitive IK+, illustrating a potential mechanism underlying coronary vascular dysfunction in a large-animal model of LV hypertrophy. Our results demonstrate the potential clinical impact of exercise on coronary vascular function in HF patients displaying pathological LV hypertrophy.
Altered membrane lipid domains limit pulmonary endothelial calcium entry following chronic hypoxia
Authors: Paffett Michael L. , Naik Jay S. , Riddle Melissa A. , Menicucci Steven D. , Gonzales Antonio J. , Resta Thomas C. , Walker Benjimen R.
Published: August 2011

Agonist-induced Ca2+entry into the pulmonary endothelium depends on activation of both store-operated Ca2+(SOC) entry and receptor-operated Ca2+(ROC) entry. We previously reported that pulmonary endothelial cell SOC entry and ROC entry are reduced in chronic hypoxia (CH)-induced pulmonary hypertension. We hypothesized that diminished endothelial Ca2+entry following CH is due to derangement of caveolin-1 (cav-1) containing cholesterol-enriched membrane domains important in agonist-induced Ca2+entry. To test this hypothesis, we measured Ca2+influx by fura-2 fluorescence following application of ATP (20 μM) in freshly isolated endothelial cells pretreated with the caveolar-disrupting agent methyl-β-cyclodextrin (mβCD; 10 mM). Cholesterol depletion with mβCD attenuated agonist-induced Ca2+entry in control endothelial cells to the level of that from CH rats. Interestingly, endothelial membrane cholesterol was lower in cells isolated from CH rats compared with controls although the density of caveolae did not differ between groups. Cholesterol repletion with a cholesterol:mβCD mixture or the introduction of the cav-1 scaffolding peptide (AP-cav; 10 μM) rescued ATP-induced Ca2+entry in endothelia from CH arteries. Agonist-induced Ca2+entry assessed by Mn2+quenching of fura-2 fluorescence was also significantly elevated by luminal AP-cav in pressurized intrapulmonary arteries from CH rats to levels of controls. Similarly, patch-clamp experiments revealed diminished inward current in response to ATP in cells from CH rats compared with controls that was restored by AP-cav. These data suggest that CH-induced pulmonary hypertension leads to reduced membrane cholesterol that limits the activity of ion channels necessary for agonist-activated Ca2+entry.
Pulmonary fibroblasts mobilize the membrane-tethered matrix metalloprotease, MT1-MMP, to destructively remodel and invade interstitial type I collagen barriers
Authors: Grant Rowe R. , Keena Daniel , Sabeh Farideh , Willis Amanda L. , Weiss Stephen J.
Published: August 2011

In acute and chronic lung disease, widespread disruption of tissue architecture underlies compromised pulmonary function. Pulmonary fibroblasts have been implicated as critical effectors of tissue-destructive extracellular matrix (ECM) remodeling by mobilizing a spectrum of proteolytic enzymes. Although efforts to date have focused on the catabolism of type I collagen, the predominant component of the lung interstitial matrix, the key collagenolytic enzymes employed by pulmonary fibroblasts remain unidentified. Herein, membrane type-1 matrix metalloprotease (MT1-MMP) is identified as the dominant and direct-acting protease responsible for the type I collagenolytic activity mediated by both mouse and human pulmonary fibroblasts. Furthermore, MT1-MMP is shown to be essential for pulmonary fibroblast migration within three-dimensional (3-D) hydrogels of cross-linked type I collagen that recapitulate ECM barriers encountered in the in vivo environment. Together, these findings demonstrate that MT1-MMP serves as a key effector of type I collagenolytic activity in pulmonary fibroblasts and earmark this pericellular collagenase as a potential target for therapeutic intervention.
The untranslated exon B of human surfactant protein A2 mRNAs is an enhancer for transcription and translation
Authors: Silveyra Patricia , Raval Manmeet , Simmons Brett , DiAngelo Susan , Wang Guirong , Floros Joanna
Published: August 2011

Two human genes, SFTPA1 (SP-A1) and SFTPA2 (SP-A2), encode surfactant protein A, a molecule of innate immunity and surfactant-related functions. Several genetic variants have been identified for both genes. These include nucleotide (nt) polymorphisms, as well as alternative splicing patterns at the 5′ untranslated region (5′UTR). Exon B (eB) is included in the 5′UTR of most SP-A2, but not SP-A1 splice variants. We investigated the role of eB in the regulation of gene expression and translation efficiency. A luciferase (Luc) reporter gene was cloned downstream of the entire (AeBD) or eB deletion mutants (del_mut) of the SP-A2 5′UTR, or heterologous 5′UTRs containing the eB sequence, or a random sequence of equal length. The del_mut constructs consisted in consecutive deletions of five nucleotides ( n = 8) within eB and the exon-exon junctions in the AeBD 5′UTR. Luc activities and mRNA levels were compared after transfection of NCI-H441 cells. We found that 1) eB increased Luc mRNA levels when placed upstream of heterologous 5′UTR sequences or the promoter region, regardless of its position and orientation; 2) translation efficiency of in vitro-generated mRNAs containing eB was higher than that of mRNAs without eB; and 3) the integrity of eB sequence is crucial for transcription and translation of the reporter gene. Thus eB 1) is a transcription enhancer, because it increases mRNA content regardless of position and orientation, 2) enhances translation when placed in either orientation within its natural 5′UTR sequence and in heterologous 5′UTRs, and 3) contains potential regulatory elements for both transcription and translation. We conclude that eB sequence and length are determinants of transcription and translation efficiency.
Resistance exercise enhances the molecular signaling of mitochondrial biogenesis induced by endurance exercise in human skeletal muscle
Authors: Wang Li , Mascher Henrik , Psilander Niklas , Blomstrand Eva , Sahlin Kent
Published: August 2011

Combining endurance and strength training (concurrent training) may change the adaptation compared with single mode training. However, the site of interaction and the mechanisms are unclear. We have investigated the hypothesis that molecular signaling of mitochondrial biogenesis after endurance exercise is impaired by resistance exercise. Ten healthy subjects performed either only endurance exercise (E; 1-h cycling at ∼65% of maximal oxygen uptake), or endurance exercise followed by resistance exercise (ER; 1-h cycling + 6 sets of leg press at 70–80% of 1 repetition maximum) in a randomized cross-over design. Muscle biopsies were obtained before and after exercise (1 and 3 h postcycling). The mRNA of genes related to mitochondrial biogenesis [(peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1)α, PGC-1-related coactivator (PRC)] related coactivator) and substrate regulation (pyruvate dehydrogenase kinase-4) increased after both E and ER, but the mRNA levels were about twofold higher after ER ( P < 0.01). Phosphorylation of proteins involved in the signaling cascade of protein synthesis [mammalian target of rapamycin (mTOR), ribosomal S6 kinase 1, and eukaryotic elongation factor 2] was altered after ER but not after E. Moreover, ER induced a larger increase in mRNA of genes associated with positive mTOR signaling (cMyc and Rheb). Phosphorylation of AMP-activated protein kinase, acetyl-CoA carboxylase, and Akt increased similarly at 1 h postcycling ( P < 0.01) after both types of exercise. Contrary to our hypothesis, the results demonstrate that ER, performed after E, amplifies the adaptive signaling response of mitochondrial biogenesis compared with single-mode endurance exercise. The mechanism may relate to a cross talk between signaling pathways mediated by mTOR. The results suggest that concurrent training may be beneficial for the adaptation of muscle oxidative capacity.
Physical inactivity as the culprit of metabolic inflexibility: evidence from bed-rest studies
Authors: Bergouignan Audrey , Rudwill Floriane , Simon Chantal , Blanc Stéphane
Published: August 2011

Although it is no longer debatable that sedentary behaviors are an actual cause of many metabolic diseases, the physiology of physical inactivity has been poorly investigated for this purpose. Along with microgravity, the physiological adaptations to spaceflights require metabolic adaptations to physical inactivity, and that is exceedingly well-simulated during the ground-based microgravity bed-rest analogs. Bed rest thus represents a unique model to investigate the mechanisms by which physical inactivity leads to the development of current societal chronic diseases. For decades, however, clinicians and physiologists working in space research have worked separately without taking full awareness of potential strong mutual questioning. This review summarizes the data collected over the last 60 years on metabolic adaptations to bed rest in healthy subjects. Our aim is to provide evidence that supports the hypothesis that physical inactivity per se is one of the primary causes in the development of metabolic inflexibility. This evidence will focus on four main tenants of metabolic inflexiblity: 1) insulin resistance, 2) impaired lipid trafficking and hyperlipidemia, 3) a shift in substrate use toward glucose, and 4) a shift in muscle fiber type and ectopic fat storage. Altogether, this hypothesis places sedentary behaviors upstream on the list of factors involved in metabolic inflexibility, which is considered to be a primary impairment in several metabolic disorders such as obesity, insulin resistance, and type 2 diabetes mellitus.
Itch Signaling in the Nervous System
Authors: Jeffry Joseph , Kim Seungil , Chen Zhou-Feng
Published: August 2011

Itch is a major somatic sensation, along with pain, temperature, and touch, detected and relayed by the somatosensory system. Itch can be an acute sensation, associated with mosquito bite, or a chronic condition, like atopic dermatitis ( 29 , 59 ). The origins of the stimulus can be localized in the periphery or systemic, and associated with organ failure or cancer. Itch is also a perception originating in the brain. Itch is broadly characterized as either histamine-dependent (histaminergic) or histamine-independent (nonhistaminergic), both of which are relayed by subsets of C fibers and by the second-order neurons expressing gastrin-releasing peptide receptor (GRPR) and spinothalamic track (STT) neurons in the spinal cord of rodents. Historically, itch research has been primarily limited to clinical and psychophysical studies and to histamine-mediated mechanisms. In contrast, little is known about the signaling mechanisms underlying nonhistaminergic itch, despite the fact that the majority of chronic itch are mediated by nonhistaminergic mechanisms. During the past few years, important progress has been made in understanding the molecular signaling of itch, largely due to the introduction of mouse genetics. In this review, we examine some of the molecular mechanisms underlying itch sensation with an emphasis on recent studies in rodents.
Transplantation of β-Endorphin Neurons into the Hypothalamus Promotes Immune Function and Restricts the Growth and Metastasis of Mammary Carcinoma
Authors: Sarkar Dipak K. , Zhang Changqing , Murugan Sengottuvelan , Dokur Madhavi , Boyadjieva Nadka I. , Ortigüela Maria , Reuhl Kenneth R. , Mojtehedzadeh Sepide
Published: August 2011

Neurobehavioral stress has been shown to promote tumor growth and progression and dampen the immune system. In this study, we investigated whether inhibiting stress hormone production could inhibit the development of mammary carcinoma and metastasis in a rat model of breast carcinogenesis. To enhance β-endorphin (BEP), the endogenous opioid polypeptide that boosts immune activity and decreases stress, we generated BEP neurons by in vitro differentiation from fetal neuronal stem cells and transplanted them into the hypothalami of rats subjected to breast carcinogenesis. BEP-transplanted rats displayed a reduction in mammary tumor incidence, growth, malignancy rate, and metastasis compared with cortical cells–transplanted rats. BEP neuron transplants also reduced inflammation and epithelial to mesenchymal transition in the tumor tissues. In addition, BEP neuron transplants increased peripheral natural killer (NK) cell and macrophage activities, elevated plasma levels of antiinflammatory cytokines, and reduced plasma levels of inflammatory cytokines. Antimetastatic effects along with stimulation of NK cells and macrophages could be reversed by treatment with the opiate antagonist naloxone, the β-receptor agonist metaproterenol, or the nicotine acetylcholine receptor antagonist methyllycaconitine. Together, our findings establish a protective role for BEP against the growth and metastasis of mammary tumor cells by altering autonomic nervous system activities that enhance innate immune function. Cancer Res; 71(19); 6282–91. ©2011 AACR.
Mechanism of the Mesenchymal–Epithelial Transition and Its Relationship with Metastatic Tumor Formation
Authors: Yao Dianbo , Dai Chaoliu , Peng Songlin
Published: August 2011

Cancer metastasis consists of a sequential series of events, and the epithelial–mesenchymal transition (EMT) and mesenchymal–epithelial transition (MET) are recognized as critical events for metastasis of carcinomas. A current area of focus is the histopathological similarity between primary and metastatic tumors, and MET at sites of metastases has been postulated to be part of the process of metastatic tumor formation. Here, we summarize accumulating evidence from experimental studies that directly supports the role of MET in cancer metastasis, and we analyze the main mechanisms that regulate MET or reverse EMT in carcinomas. Given the critical role of MET in metastatic tumor formation, the potential to effectively target the MET process at sites of metastasis offers new hope for inhibiting metastatic tumor formation. Mol Cancer Res; 9(12); 1608–20. ©2011 AACR.
Dietary Vitamin D and Vitamin D Receptor Level Modulate Epithelial Cell Proliferation and Apoptosis in the Prostate
Authors: Kovalenko Pavlo L. , Zhang Zhentao , Yu Jun-Ge , Li Yan , Clinton Steven K. , Fleet James C.
Published: August 2011

Low vitamin D (VD) status may increase prostate cancer risk but experimental evidence for this relationship is modest. We tested whether low VD status or VD receptor (VDR) deletion influences prostate epithelial cell (PEC) biology using intact mice, castrated mice, or castrated mice treated with testosterone propionate (TP, 2.5 mg/kg BW). PEC proliferation (Ki-67 staining) and apoptosis (TUNEL method) were determined in the anterior prostate (AP). In study 1, wild-type (WT) and TgAPT121 mice (a model of prostate intraepithelial neoplasia) were fed diets with 25, 200 (reference diet), or 10,000 IU VD/kg diet (as vitamin D3) prior to castration/repletion. Serum 25 hydroxyvitamin D levels were 26, 78, and 237 nmol/L in the three diet groups, respectively. Castration reduced proliferation and increased apoptosis in the AP while TP reversed these effects. Low VD diet increased proliferation in WT (+82%) and TgAPT121 (+24%) mice while it suppressed apoptosis in WT (−29%) and TgAPT121 (−37%) mice. This diet also increased the severity of prostate intraepithelial neoplastic lesions in the AP of intact TgAPT121 mice. In study 2, mice with PEC-specific VDR deletion (PEC VDR KO) were examined after castration/repletion. TUNEL staining was 60% lower in castrated PEC VDR KO mice compared with castrated WT mice. In castrated mice given TP, Ki-67 staining was 2-fold higher in PEC VDR KO compared with WT mice. Our data show that low diet VDR or VDR deletion provide a prostate environment that is permissive to early procarcinogenic events that enhance prostate cancer risk. Cancer Prev Res; 4(10); 1617–25. ©2011 AACR.
Proteomic Signature of Thrombin-Activated Platelets After In Vivo Nitric Oxide–Donor Treatment
Authors: Peña Esther , Padro Teresa , Molins Blanca , Vilahur Gemma , Badimon Lina
Published: August 2011

Objective—

Growing insight into the antiplatelet properties of new nitric oxide (NO) donors has expanded their potential use in cardiovascular diseases. As such, we reported that oral administration of a new exogenous NO donor (LA419) induced significant inhibition of platelet deposition on damaged vascular wall without provoking hypotension in an in vivo experimental model. Thrombin is one of the major triggers of platelet deposition and thrombosis on injured vessels; however, the effects of NO on thrombin-induced platelet activation are not fully known. Here, our aim was to investigate the inhibitory effects of exogenous NO administration on the major changes in platelet proteins induced by thrombin.

Methods and Results—

Platelets were obtained from a group of swine orally treated with LA419 (0.9 mg kg
−1
) or placebo for 8 days. Washed platelets were incubated with thrombin (0.4 NIH U/mL). Platelet proteins were then sequentially extracted based on differential solubility and studied by two-dimensional electrophoresis, mass spectrometry (matrix-assisted laser desorption ionization/time of flight), Western blot, and confocal immunofluorescence. NO treatment abrogated thrombin effects on 24 proteins involved in actin assembly, signaling, and metabolic activity. NO treatment prevented thrombin-induced translocation of gelsolin, filamin, 14-3-3ζ, phosphatidylinositol 3-kinase-γ isoform, and growth factor receptor-bound protein 2 (Grb2).

Conclusion—

Our results show that exogenous NO donor treatment renders platelets less sensitive to thrombin activation and inhibits thrombosis by interfering with the platelet shape change machinery.
A Novel Compound Inhibits Reconstituted High-Density Lipoprotein Assembly and Blocks Nascent High-Density Lipoprotein Biogenesis Downstream of Apolipoprotein AI Binding to ATP-Binding Cassette Transporter A1–Expressing Cells
Authors: Lyssenko Nicholas N. , Brubaker Gregory , Smith Bradley D. , Smith Jonathan D.
Published: August 2011

Objective—

Nascent high-density lipoprotein (HDL) particles form from cellular lipids and extracellular lipid-free apolipoprotein AI (apoAI) in a process mediated by ATP-binding cassette transporter A1 (ABCA1). We have sought out compounds that inhibit nascent HDL biogenesis without affecting ABCA1 activity.

Methods and Results—

Reconstituted HDL (rHDL) formation and cellular cholesterol efflux assays were used to show that 2 compounds that bond via hydrogen with phospholipids inhibit rHDL and nascent HDL production. In rHDL formation assays, the inhibitory effect of compound 1 (methyl 3α-acetoxy-7α,12α-di[(phenylaminocarbonyl)amino]-5β-cholan-24-oate), the more active of the 2, depended on its ability to associate with phospholipids. In cell assays, compound 1 suppressed ABCA1-mediated cholesterol efflux to apoAI, the 18A peptide, and taurocholate with high specificity, without affecting ABCA1-independent cellular cholesterol efflux to HDL and endocytosis of acetylated low-density lipoprotein and transferrin. Furthermore, compound 1 did not affect ABCA1 activity adversely, as ABCA1-mediated shedding of microparticles proceeded unabated and apoAI binding to ABCA1-expressing cells increased in its presence.

Conclusion—

The inhibitory effects of compound 1 support a 3-step model of nascent HDL biogenesis: plasma membrane remodeling by ABCA1, apoAI binding to ABCA1, and lipoprotein particle assembly. The compound inhibits the final step, causing accumulation of apoAI in ABCA1-expressing cells.
Therapeutic Angiogenesis of Human Early Endothelial Progenitor Cells Is Enhanced by Thrombomodulin
Authors: Li Jiun-Yi , Su Cheng-Huang , Wu Yih-Jer , Tien Ting-Yi , Hsieh Chin-Ling , Chen Chih-Hao , Tseng Ya-Ming , Shi Guey-Yueh , Wu Hua-Lin , Tsai Cheng-Ho , Lin Fang-Yue , Yeh Hung-I
Published: August 2011

Objective—

We examined the effect of thrombomodulin (TM) domains 2 and 3 (TMD23) on human early endothelial progenitor cells (EPCs).

Methods and Results—

TM was expressed and released by human EPCs cultured from peripheral blood mononuclear cells (PBMCs). Addition of TMD23 (100 ng/mL) to the cultured PBMCs increased the colony-forming units, chemotactic motility, matrix metalloproteinase activity, and interleukin-8 secretion but decreased tumor necrosis factor-α (TNF-α) release. Analysis of the signal pathway showed that TMD23 activated Akt. Inhibition of phosphatidylinositol-3 kinase–Akt blocked the effects of TMD23 on chemotactic motility, matrix metalloproteinase-9, interleukin-8, and TNF-α. In hindlimb ischemia mice, laser Doppler perfusion imaging of the ischemic limb during the 21 days after arterial ligation showed that the perfusion recovered best with intraperitoneal infusion of TMD23 plus local injection of early EPCs, followed by either infusion of TMD23 or injection of the cells. Animals without either treatment had the worst results. Animals treated with TMD23 also had lower circulating and tissue levels of TNF-α.

Conclusion—

TM is expressed and released by human circulating EPCs. Exogenous TMD23 enhances the angiogenic potential of early EPCs in vitro through activation of phosphatidylinositol-3 kinase-Akt pathway. Coadministration of TMD23 plus early EPCs augments therapeutic angiogenesis of the EPCs in ischemic tissues.
A Novel Strategy Using Cardiac Sodium Channel Polymorphic Fragments To Rescue Trafficking-Deficient
SCN5A
Mutations
Authors: Shinlapawittayatorn Krekwit , Dudash Lynn A. , Du Xi X. , Heller Lisa , Poelzing Steven , Ficker Eckhard , Deschênes Isabelle
Published: August 2011

Background—

Brugada syndrome (BrS) is associated with mutations in the cardiac sodium channel (Na
v
1.5). We previously reported that the function of a trafficking-deficient BrS Na
v
1.5 mutation, R282H, could be restored by coexpression with the sodium channel polymorphism H558R. Here, we tested the hypothesis that peptide fragments from Na
v
1.5, spanning the H558R polymorphism, can be used to restore trafficking of trafficking-deficient BrS sodium channel mutations.

Methods and Results—

Whole-cell patch clamping revealed that cotransfection in human embryonic kidney (HEK293) cells of the R282H channel with either the 40- or 20-amino acid cDNA fragments of Na
v
1.5 containing the H558R polymorphism restored trafficking of this mutant channel. Fluorescence resonance energy transfer suggested that the trafficking-deficient R282H channel was misfolded, and this was corrected on coexpression with R558-containing peptides that restored trafficking of the R282H channel. Importantly, we also expressed the peptide spanning the H558R polymorphism with 8 additional BrS Na
v
1.5 mutations with reduced currents and demonstrated that the peptide was able to restore significant sodium currents in 4 of them.

Conclusions—

In the present study, we demonstrate that small peptides, spanning the H558R polymorphism, are sufficient to restore the trafficking defect of BrS-associated Na
v
1.5 mutations. Our findings suggest that it might be possible to use short cDNA constructs as a novel strategy tailored to specific disease-causing mutants of BrS.
Impaired Mitochondrial Biogenesis Precedes Heart Failure in Right Ventricular Hypertrophy in Congenital Heart Disease
Authors: Karamanlidis Georgios , Bautista-Hernandez Victor , Fynn-Thompson Francis , del Nido Pedro , Tian Rong
Published: August 2011

Background—

The outcome of the surgical repair in congenital heart disease correlates with the degree of myocardial damage. In this study, we determined whether mitochondrial DNA depletion is a sensitive marker of right ventricular (RV) damage and whether impaired mitochondrial DNA (mtDNA) replication contributes to the transition from compensated hypertrophy to failure.

Methods and Results—

RV samples obtained from 31 patients undergoing cardiac surgery were compared with 5 RV samples from nonfailing hearts (control). Patients were divided into compensated hypertrophy and failure groups, based on preoperative echocardiography, catheterization, and/or MRI data. Mitochondrial enzyme activities (citrate synthase and succinate dehydrogenase) were maintained during hypertrophy and decreased by ≈40% (
P
<0.05 versus control) at the stage of failure. In contrast, mtDNA content was progressively decreased in the hypertrophied RV through failure (by 28±8% and 67±11%, respectively,
P
<0.05 for both), whereas mtDNA-encoded gene expression was sustained by increased transcriptional activity during compensated hypertrophy but not in failure. Mitochondrial DNA depletion was attributed to reduced mtDNA replication in both hypertrophied and failing RV, and it was independent of PGC-1 downregulation but was accompanied by reduced expression of proteins constituting the mtDNA replication fork. Decreased mtDNA content in compensated hypertrophy was also associated with pathological changes of mitochondria ultrastructure.

Conclusions—

Impaired mtDNA replication causes early and progressive depletion of mtDNA in the RV of the patients with congenital heart disease during the transition from hypertrophy to failure. Decreased mtDNA content probably is a sensitive marker of mitochondrial injury in this patient population.
Molecular MRI of Acute Necrosis With a Novel DNA-Binding Gadolinium Chelate
Authors: Huang Shuning , Chen Howard H. , Yuan Hushan , Dai Guangping , Schuhle Daniel T. , Mekkaoui Choukri , Ngoy Soeun , Liao Ronglih , Caravan Peter , Josephson Lee , Sosnovik David E.
Published: August 2011

Background—

Current techniques to image cell death in the myocardium are largely nonspecific. We report the use of a novel DNA-binding gadolinium chelate (Gd-TO) to specifically detect the exposed DNA in acutely necrotic (ruptured) cells in vivo.

Methods and Results—

In vivo MRI was performed in 20 mice with myocardial infarction (MI). The mice were injected with Gd-TO or Gd-DTPA at varying time points after MI. MRI was performed 2 hours after probe injection, to avoid nonspecific signal from the late gadolinium enhancement effect. Cell rupture (Gd-TO uptake) was present within 2 hours of infarction but peaked 9 to 18 hours after the onset of injury. A significant increase in the longitudinal relaxation rate (R
1
) in the infarct was seen in mice injected with Gd-TO within 48 hours of MI, but not in those injected more than 72 hours after MI (R
1
=1.24±0.08 and 0.92±0.03 s
−1
, respectively,
P
<0.001). Gd-DTPA, unlike Gd-TO, washed completely out of acute infarcts within 2 hours of injection (
P
<0.001). The binding of Gd-TO to exposed DNA in acute infarcts was confirmed with fluorescence microscopy.

Conclusions—

Gd-TO specifically binds to acutely necrotic cells and can be used to image the mechanism and chronicity of cell death in injured myocardium. Cell rupture in acute MI begins early but peaks many hours after the onset of injury. The ruptured cells are efficiently cleared by the immune system and are no longer present in the myocardium 72 hours after injury.
Peroxiredoxin 2 Deficiency Exacerbates Atherosclerosis in Apolipoprotein E–Deficient Mice
Authors: Park Jong-Gil , Yoo Ji-Young , Jeong Se-Jin , Choi Jae-Hoon , Lee Mi-Ran , Lee Mi-Ni , Hwa Lee Jeong , Kim Hyoung Chin , Jo Hanjoong , Yu Dae-Yeul , Kang Sang Won , Rhee Sue Goo , Lee Mun-Han , Oh Goo Taeg
Published: August 2011

Rationale:

Peroxiredoxin 2 (Prdx2), a thiol-specific peroxidase, has been reported to regulate proinflammatory responses, vascular remodeling, and global oxidative stress.

Objective:

Although Prdx2 has been proposed to retard atherosclerosis development, no direct evidence and mechanisms have been reported.

Methods and Results:

We show that Prdx2 is highly expressed in endothelial and immune cells in atherosclerotic lesions and blocked the increase of endogenous H
2
O
2
by atherogenic stimulation. Deficiency of Prdx2 in apolipoprotein E–deficient (ApoE
−/−
) mice accelerated plaque formation with enhanced activation of p65, c-Jun, JNKs, and p38 mitogen-activated protein kinase; and these proatherogenic effects of Prdx2 deficiency were rescued by administration of the antioxidant ebselen. In bone marrow transplantation experiments, we found that Prdx2 has a major role in inhibiting atherogenic responses in both vascular and immune cells. Prdx2 deficiency resulted in increased expression of vascular adhesion molecule-1, intercellular adhesion molecule-1, and monocyte chemotactic protein-1, which led to increased immune cell adhesion and infiltration into the aortic intima. Compared with deficiency of glutathione peroxidase 1 or catalase, Prdx2 deficiency showed a severe predisposition to develop atherosclerosis.

Conclusions:

Prdx2 is a specific peroxidase that inhibits atherogenic responses in vascular and inflammatory cells, and specific activation of Prdx2 may be an effective means of antiatherogenic therapy.