Using small molecules to facilitate exchange of bicarbonate and chloride anions across liposomal membranes

Bicarbonate is involved in a wide range of biological processes, which include respiration, regulation of intracellular pH and fertilization. In this study we use a combination of NMR spectroscopy and ion-selective electrode techniques to show that the natural product prodigiosin, a tripyrrolic molecule produced by microorganisms such as Streptomyces and Serratia, facilitates chloride/bicarbonate exchange (antiport) across liposomal membranes. Higher concentrations of simple synthetic molecules based on a 4,6-dihydroxyisophthalamide core are also shown to facilitate this antiport process. Although it is well known that proteins regulate Cl-/HCO3- exchange in cells, these results suggest that small molecules may also be able to regulate the concentration of these anions in biological systems

Reversible Data Hiding Methods : A Survey

This paper presents a survey of various reversible data hiding methods. Data hiding is the process of hiding information in a cover media . Most commonly used media for data hiding is image. But during the hiding and extraction of data there are chances for the distortion of image. Reversible data hiding methods are used to solve this problem

Social and content hybrid image recommender system for mobile social networks

One of the advantages of social networks is the possibility to socialize and personalize the content created or shared by the users. In mobile social networks, where the devices have limited capabilities in terms of screen size and computing power, Multimedia Recommender Systems help to present the most relevant content to the users, depending on their tastes, relationships and profile. Previous recommender systems are not able to cope with the uncertainty of automated tagging and are knowledge domain dependant. In addition, the instantiation of a recommender in this domain should cope with problems arising from the collaborative filtering inherent nature (cold start, banana problem, large number of users to run, etc.). The solution presented in this paper addresses the abovementioned problems by proposing a hybrid image recommender system, which combines collaborative filtering (social techniques) with content-based techniques, leaving the user the liberty to give these processes a personal weight. It takes into account aesthetics and the formal characteristics of the images to overcome the problems of current techniques, improving the performance of existing systems to create a mobile social networks recommender with a high degree of adaptation to any kind of user

Brain Abscess as a Manifestation of Hereditary Hemorrhagic Telangiectasia in a Pediatric Patient: A Case Report

Hereditary Hemorrhagic Telangiectasia (HHT) is a disease defined by abnormal endothelial cell development thatmanifests as cutaneous telangiectasias, recurrent epistaxis, and visceral organ arteriovenous malformations. This report’s objective is to exhibit a unique presentation of an uncommon disease within the pediatric population. It also provides excellent educational value through prioritizing the investigation of alternative diagnoses in a pediatric patient who develops a brain abscess without any known risk factors. Herein we report the case of a previously healthy 17-year-old femalewho developed sudden aphasia and a newonset tonic-clonic seizure after 3 days of headache and shortness of breath. She had a past medical history of migraines and recurrent epistaxis. Imaging confirmed a ringenhancing lesion in her frontal lobe, which suggested a brain abscess. She was treated with intravenous antibiotics and steroids. Her neurological symptoms subsided and she was discharged home. Continuedwork-up revealed numerous arteriovenous malformations, which likely contributed to her brain abscess, and she was diagnosed with HHT. HHT should be suspected in pediatric patients who develop brain abscesswithout any other risk factors.Additionally, new onset neurological symptoms in pediatric patients should be investigated promptly with head imaging. Timely identification and initiation of therapy is crucial due to the high morbidity and mortality associated with brain abscess, especially in HHT patients. A 17-year-old female was transported to the emergency department after suffering from a sudden episode of inability to speak followed by a single seizure episode at school. While in her classroom, she reported a difficulty “finding words” and stood up in panic fromher desk. She approached the teacher to ask permission to leave the room. Unable to speak, she began to write on a sheet of paper, but her writing soon became incoherent to both the teacher and to herself.Her teacher sent her to the nurse’s office, where she suffered a new-onset generalized tonic- clonic seizure and the emergency medical Brain Abscess as a Manifestation of Hereditary Hemorrhagic Telangiectasia in a Pediatric Patient ¹University of South Florida College of Medicine, Tampa, FL ²Children’s Hospital at Lehigh Valley Health Network, Allentown, PA Jose M. Soto, BS¹; Tibisay Villalobos, MD² Corresponding Author: Jose M. Soto, BS, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL 33612. Email: [email protected] The authors claim no conflicts of interest or disclosures. AMSRJ 2015; 2(1):48-53 http://dx.doi.org/10.15422/amsrj.2015.05.005 ABSTRACT CASE PRESENTATION AMSRJ 2015 Volume 2, Number 1 49 service (EMS) was called. This seizure lasted a few minutes and resolved by the time the EMS arrived. During the seizure, she also suffered an episode of epistaxis. She was able to communicate on arrival to the ED, although with some difficulty, and stated that she had a 3-day history of headaches and shortness of breath. She also reported a history of headaches since the age of twelve. She stated her headaches usually begin with an aura of “shimmering prisms and cones of lights.” The pain is typically unilateral and acetaminophen provides some relief. These headacheswere sometimes associatedwith nausea and mild photophobia. They typically resolvedwith sleep.Over the last three days, however, the headaches had worsened, and ibuprofen became ineffective. She denied any recent head trauma. Her vital signs included a blood pressure of 120/73 mmHg, heart rate of 117 beats/minute, respiratory rate of 16 breaths/minute, temperature of 99.6° Fahrenheit.On exam, she appeared anxious and in mild distress. Her cranial nerves II-XII were grossly intact, and her pupils were equally round and reactive to light. Dried blood was found in both of her nostrils; there was no active bleeding. There were no meningeal signs during her neck exam. Her cardiovascular, pulmonary, and abdominal exams were all within normal limits. Her neurological exam was also grossly normal with a Glasgow Coma Scale score of 15, but she continued having difficulty “finding words.” A complete blood count with differential was drawn: hemoglobin was 14.8 g/ dL, hematocrit was 45.7%, white blood cells were 14.8 cells/mcL (71% neutrophils, 18% lymphocytes, 6% monocytes, 5% eosinophils), and platelets were 245,000/mcL. A computed tomography (CT) scan of her head without contrast (Figure 1) showed an area of abnormally low density in the left frontal lobe that was suggestive of vasogenic edema as the grey-white matter differentiation was maintained and the edema primarily involved the white matter. No evidence of intracranial hemorrhagewas found. While air or maturing hematomas may also cause lowdensity on CT scans, thesewere ruled out due to the lack of a history of head trauma. Given the history of rapid onset neurologic symptoms and the elevated white blood cell count, as well as imaging that suggested an area of edemawithout obvious intracranial bleeding, a brain abscess was suspected. Therefore, she was admitted to the pediatric intensive care unit and started on empiric intravenous antibiotic therapy with ceftriaxone, metronidazole, and vancomycin as well as levetiracetamfor seizure prophylaxis. Amagnetic resonance imaging (MRI) scanwith and without contrast (Figures 2 and 3) confirmed an area of vasogenic edema surrounding a ring-enhancing lesion in the left frontal lobe. Themidline shift seen on the earlierCTscanwas also evident on theseMRI images.Although the differential diagnosis for ring-enhancing lesions includes glioblastoma multiforme, brain metastasis, infarct, contusion, and neurocysticerosis, Figure 1. Initial CT scan taken at presentation to the hospital showing an area suggestive of vasogenic edema in the left frontal lobe (arrow) and mild midline shift. BRIEF REPORTS BRAIN ABSCESS AMSRJ 50 2015 Volume 2, Number 1 thesewere ruled out due to history and age of the patient. A follow up magnetic resonance angiogram (MRA) of the head (Figure 4) demonstrated mass effect of the lesion on the medial cerebral artery branches on the left side, but there was no evidence of aneurysms, arteriovenous malformations, or major vessel occlusion. These findingswere also consistentwith a brain abscess. The patient continued to have headaches and six days after admission, she became increasingly confused and developed right upper extremity weakness in addition to left facial drooping. A Figure 2. T1-weighted coronalMRIwith contrast demonstrating a left sided ring-enhancing lesion (arrow) surrounded by vasogenic edema and also a midline shift. Figure 3. T2-weighted transverse MRI with contrast that highlights the area of vasogenic edema (arrow) and also further demonstrates the midline shift seen in previous images. Figure 4. Coronal MRA of the head showing mass effect of the lesion on the branches of the left middle cerebral artery (arrow). Figure 5. Repeat coronal MRI with the blue arrow pointing to the original lesion and the red arrow pointing to the new lesion. BRAIN ABSCESS BRIEF REPORTS AMSRJ 2015 Volume 2, Number 1 51 repeatMRI (Figure 5) demonstrated a new area of enhancement and diffusion restriction inferolaterally to the original lesion as well as increased vasogenic edema. The following day, she underwent a CT-guided biopsy of the original lesion with cultures. The tissue culture grew Micrococcus luteus/lylae. After the procedure, IV dexamethasone was added to her antibiotics to reduce brain tissue swelling. She continued this treatment regime for two additional weeks as her neurological symptoms began to subside. The patient was then discharged home for the remaining five weeks of IV antibiotics. During this time frame, her facial palsy resolved and she regained strength in her right upper extremity. Her headaches also improved. During her admission, itwas discovered that she had a past medical history significant for migraine headaches since the age of twelve and recurrent episodes of epistaxis. It was also revealed that her mother had hereditary hemorrhagic telangiectasia (HHT). There was a high level of suspicion forHHT due to family history and recent events, so studies of the chest to search for pulmonary arteriovenous malformations (PAVMs) aswell as a transcranialDoppler studywere performed.Numerous PAVMswere found in the patient’s left upper lobe aswell as in her right middle lobe (Figure 6). The transcranial Doppler study with agitated saline also demonstrated an arteriovenous shunt in themiddle cerebral artery. The patient met 3 of the 4 diagnostic Curacao criteria for HHT¹ (Table 1) and itwas concluded that her undiagnosedHHT had predisposed her to this brain abscess. The patient completed her IV antibiotic course and followupMRI studies demonstrated that the brain abscess had resolved. The majority of the PAVMs seen on arteriogram have since been obliterated. Figure 6. Pulmonary arteriogram demonstrating a dominant arteriovenous malformation in the inferior aspect of the upper lobe (arrow) along with numerous smaller malformations. Curacao Criteria for HHT 1. Recurrent Epistaxis 2. Telangiectasias 3. Visceral Manifestations 4. Affected 1st degree relative 3-4 criteria met: definitive HHT 2 criteria met: suspected HHT 1 criteria met: unlikely to be HHT ! Table 1. Curacao Criteria for the diagnosis of HHT BRIEF REPORTS BRAIN ABSCESS AMSRJ 52 2015 Volume 2, Number 1 Epidemiology and Pathophysiology HHT is an autosomal dominant inherited disorder that affects 1 in 10,000 people with no preference for either sex.² It is most common in the Caucasian population and is 97%penetrant.²Almost 30%of patients do not have a family history of the disease.² The genes affected by this disorder both code for Transforming Growth Factor-β receptors: ENG on chromosome 9q34.1 andACVRL-1 (activinAreceptor type IIlike 1) on chromosome 12q13.13.³ These genes are crucial in the development of vascular endothelial cells during angiogenesis and either mutation will manifest in the same manner. Clinical Manifestations The syndrome is defined by telangiectasias, or dilated post-capillary venules, of the skin, mucousmembranes and internal organs.Cutaneous telangiectasias typically occur on the face, hands, and lips. When telangiectasias occur in the nasal mucosa, they may cause spontaneous recurrent epistaxis which is the first symptom formore than 90%of patients.4,5More than 50% of patients with HHT will manifest with this symptom before the age of twenty.¹ The bleeding can be so severe that 10-30%of patientswill require blood transfusions over the course of their lifetime. In roughly 40% of patients, the gastrointestinal system is involved and can also be the source of significant blood loss.3,6 The diagnostic Curacao criteria¹ (Table 1) require three of the following four findings: recurrent epistaxis, cutaneous telangiectasias, visceral organ involvement (i.e., arteriovenous malformations thatmay bleed) and an affected firstdegree relative. Few patients, however, manifest enough signs and symptoms within the first three decades of life to meet the criteria, and therefore, it is recommended that asymptomatic children of HHT patients be genetically screened for the disease.¹ Neurological manifestations In a healthy patient, the lung capillary beds function to filter the blood before it is pumped to the brain, but pulmonary vascular malformations (PAVMs) found in HHT patients compromise this protection system.7 Large PAVMs can result in paradoxical micro-emboli entering cerebral circulation and subsequent ischemic brain injury (i.e., stroke). Abscess formation can be caused by direct seeding of pathogenic bacteria into the brain parenchyma or secondarily after an anoxic brain injury creates an environment suitable for bacteria growth. About 1% of HHT patients can develop cerebral abscess or septic meningitis, which is significantly higher than the general population.7 For the reasons noted above, PAVMs are a significant source of morbidity and mortality in HHT patients7 and they can also lead to high-output cardiac failure in later life.² Brain abscesses are usually of poly-microbial origin; only the slow growing members of the Micrococcus genuswere isolated in this case because empiric antimicrobial therapy had already begun by the time of the biopsy.8, 9 It is important to note that brain abscesses do not commonly present with the typical cardinal signs of infection: fever, leukocytosis, or positive blood cultures. 10 The neurological symptoms of brain abscesses are due in large part to the mass effect of the lesion on surrounding structures.Consequently, the symptoms can include a wide spectrum of neurologic symptoms such as aphasia, seizures, and headaches depending on the location of the lesion. HHT patients can also develop cerebral vascular malformations (CAVMs), which can manifest as various neurological symptoms. Approximately one-quarter of HHT patients DISCUSSION BRAIN ABSCESS BRIEF REPORTS AMSRJ 2015 Volume 2, Number 1 53 will have a CAVM in their lifetime and there is a 0.5%bleeding risk per year.¹ The treatment of choice for arteriovenousmalformations remains embolization of the feeding blood vessels.11 •The differential diagnosis for a pediatric patient without any known risk factors who develops a brain abscess should include HHT. •Brain abscesses are typically poly-microbial in nature and do not present with the usual signs of infection, such as fever, leukocytosis, or positive blood cultures. 1. Faughnan ME, Palda VA, Garcia-Tsao G, et al. International guidelines for the diagnosis and management of hereditary haemorrhagic telangiectasia. Journal of medical genetics. 2011;48 (2):73-87. 2. Daroff R, ed. Bradley\u27s Neurology in Clinical Practice. 6th ed. Philadelphia, PA: W.B. Saunders; 2012. 3.Mark Feldman LF, Lawrence Brandt, eds. Sleisenger and Fordtran\u27s gastrointestinal and liver disease: pathophysiology, diagnosis, management. Philadelphia, PA: Saunders Elsevier; 2010. 4. Sadick H, Sadick M, Gotte K, et al. Hereditary hemorrhagic telangiectasia: an update on clinical manifestations and diagnostic measures. Wiener klinische Wochenschrift. 2006;118(3-4):72-80. 5. Murtagh B, Fulgham JR. 23-year-old woman with increasing frequency ofmigraine headaches.MayoClinic proceedings. 2002;77 (10):1105-8. 6.ChenCW, Jao SW,WuCC, et al.Red spots on the hands and red blood in the stools. Lancet. 2008;371(9619):1190. 7. Moradi M, Adeli M. Brain abscess as the first manifestation of pulmonary arteriovenous malformation: A case report. Advanced biomedical research. 2014;3:28. 8. Frazier JL, Ahn ES, Jallo GI. Management of brain abscesses in children. Neurosurgical focus. 2008;24(6):E8. 9.SelladuraiBM,SivakumaranS,AiyarS, et al. Intracranial suppuration caused by Micrococcus luteus. British journal of neurosurgery. 1993;7(2):205-7. 10. Dong SL, Reynolds SF, Steiner IP. Brain abscess in patients with hereditary hemorrhagic telangiectasia: case report and literature review. The Journal of emergency medicine. 2001;20(3):247-51. 11. Meek ME, Meek JC, Beheshti MV. Management of pulmonary arteriovenous malformations. Seminars in interventional radiology. 2011;28(1):24-31. REFERENCES LEARNING POINTS BRIEF REPORTS BRAIN ABSCES

Different healthy habits between northern and southern Spanish school children

Aim: Healthy habits are influenced by several factors such as, geographical location. The aims of this study were to describe and compare healthy habits within two populations of sixth-grade primary school children (aged 11-12 years) from Northern and Southern Spain. Subject and Methods: A cross-sectional study using two representative samples of school children was conducted. Participants came from Logroño (n=329), in the North and Granada (n=284), in the South of Spain. Socio-demographic and anthropometric variables, adherence to the Mediterranean diet, aerobic fitness, and healthy lifestyles were recorded. Results: Boys reported higher level of physical activity and aerobic fitness than girls (p=0.000). Southern school children reported significantly higher adherence to the Mediterranean diet (♀: p=0.041; ♂: p=0.008), and lower aerobic fitness (♀: p=0.000; ♂: p=0.042) and hours of nightly sleep (♀: p=0.008, ♂: p=0.007) than Northern school children. Southern boys also reported lower levels of physical activity (p=0.013). There were slight or moderate correlations among all habits measured (physical activity, diet, screen and sleep time). Additionally, physical activity level was inversely related to body mass index in Northern boys (p=0.020) and Southern girls (p=0.024). Conclusions: Results showed differences in physical activity, eating and sleep habits, and aerobic fitness, according to geographical location. The relationships found among lifestyle habits indicate the need of health promotion interventions nationally and considering the differences discussed here

On the relationship between the reversed hazard rate and elasticity

Despite hazard and reversed hazard rates sharing a number of similar aspects, reversed hazard functions are far less frequently used. Understanding their meaning is not a simple task. The aim of this paper is to expand the usefulness of the reversed hazard function by relating it to other well-known concepts broadly used in economics: (linear or cumulative) rates of increase and elasticity. This will make it possible (i) to improve our understanding of the consequences of using a particular distribution and, in certain cases, (ii) to introduce our hypotheses and knowledge about the random process in a more meaningful and intuitive way, thus providing a means to achieving distributions that would otherwise be hardly imaginable or justifiable

Deconstructing the DGAT1 enzyme: membrane interactions at substrate binding sites

Diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in the triacylglyceride synthesis pathway. Bovine DGAT1 is an endoplasmic reticulum membrane-bound protein associated with the regulation of fat content in milk and meat. The aim of this study was to evaluate the interaction of DGAT1 peptides corresponding to putative substrate binding sites with different types of model membranes. Whilst these peptides are predicted to be located in an extramembranous loop of the membrane-bound protein, their hydrophobic substrates are membrane-bound molecules. In this study, peptides corresponding to the binding sites of the two substrates involved in the reaction were examined in the presence of model membranes in order to probe potential interactions between them that might influence the subsequent binding of the substrates. Whilst the conformation of one of the peptides changed upon binding several types of micelles regardless of their surface charge, suggesting binding to hydrophobic domains, the other peptide bound strongly to negatively-charged model membranes. This binding was accompanied by a change in conformation, and produced leakage of the liposome-entrapped dye calcein. The different hydrophobic and electrostatic interactions observed suggest the peptides may be involved in the interactions of the enzyme with membrane surfaces, facilitating access of the catalytic histidine to the triacylglycerol substrates

A calibration protocol for population-specific accelerometer cut-points in children

PurposeTo test a field-based protocol using intermittent activities representative of children\u27s physical activity behaviours, to generate behaviourally valid, population-specific accelerometer cut-points for sedentary behaviour, moderate, and vigorous physical activity.MethodsTwenty-eight children (46% boys) aged 10&ndash;11 years wore a hip-mounted uniaxial GT1M ActiGraph and engaged in 6 activities representative of children\u27s play. A validated direct observation protocol was used as the criterion measure of physical activity. Receiver Operating Characteristics (ROC) curve analyses were conducted with four semi-structured activities to determine the accelerometer cut-points. To examine classification differences, cut-points were cross-validated with free-play and DVD viewing activities.ResultsCut-points of &le;372, &gt;2160 and &gt;4806 counts&bull;min&minus;1 representing sedentary, moderate and vigorous intensity thresholds, respectively, provided the optimal balance between the related needs for sensitivity (accurately detecting activity) and specificity (limiting misclassification of the activity). Cross-validation data demonstrated that these values yielded the best overall kappa scores (0.97; 0.71; 0.62), and a high classification agreement (98.6%; 89.0%; 87.2%), respectively. Specificity values of 96&ndash;97% showed that the developed cut-points accurately detected physical activity, and sensitivity values (89&ndash;99%) indicated that minutes of activity were seldom incorrectly classified as inactivity.ConclusionThe development of an inexpensive and replicable field-based protocol to generate behaviourally valid and population-specific accelerometer cut-points may improve the classification of physical activity levels in children, which could enhance subsequent intervention and observational studies.<br /

Properties of Graphene: A Theoretical Perspective

In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic