Sexting Associated with Risky Sexual Behavior in Girls .


Sexting is prevalent among teenagers and is associated with risky sexual activity among girls, according to a study in the Archives of Pediatrics & Adolescent Medicine.

Nearly 1000 ethnically diverse students in public high schools in the Houston area completed surveys about sexting and their sexual behaviors.

Overall, more than a quarter of the students reported sending a naked picture of themselves via text or e-mail, and over half had been asked to do so. For girls who sexted, the following behaviors were more common: starting dating, having sex, having multiple sex partners, and using alcohol or drugs before sex. The same association was not observed in boys.

The authors advise clinicians: “Given [sexting’s] prevalence and link to sexual behavior, pediatricians and other tween-focused and teen-focused health care providers may consider screening for sexting behaviors. Asking about sexting could provide insight into whether a teen is likely engaging in other sexual behaviors.”

Source: Archives of Pediatrics & Adolescent Medicine .

Serious Post-Discharge Medication Errors Are Common .


A study in two academic hospital centers in the U.S. finds that medication errors after discharge for treatment of cardiovascular disease are common and that a pharmacist-based intervention to address the problem may have little benefit. The study appears in the Annals of Internal Medicine.

Researchers studied 850 patients hospitalized with acute coronary syndrome or heart failure. Participants were randomized to usual care or to an intervention consisting of medication reconciliation by a pharmacist, counseling, provision of aids (like pill boxes) to increase adherence, and telephone follow-up. The incidence of medication errors at 30 days did not differ significantly between the groups (about 50% in each). Roughly 75% of errors were characterized as “significant” in severity, 23% as “serious,” and 2% as “life-threatening.”

Examples of adverse drug events included a patient found to have an INR higher than 14 at 8 days after discharge, and a patient whose insulin dose was poorly managed, resulting in several episodes of hypoglycemia.

Source: Annals of Internal Medicine

 

Fetal Safety of Newer Antiepileptic Drugs During Pregnancy.


Risk for major congenital malformations is low for most AEDs, although newer AEDs are not necessarily safer than older ones.

Increasing numbers of reproductive-aged women with epilepsy are being prescribed newer antiepileptic drugs (AEDs; lamotrigine, levetiracetam, and topiramate) over traditional AEDs (e.g., carbamazepine, phenytoin, valproate); however, fetal safety remains a concern. Researchers assessed rates of major congenital malformations (MCMs) diagnosed within 12 weeks after birth in offspring of North American AED Pregnancy Registry participants (enrolled from 1997 to 2011) who received monotherapy with old or new AEDs during the first trimester. An internal comparison group recruited through the registry consisted of pregnant women without epilepsy who were not taking AEDs.

In all, 4899 women receiving AED monotherapy (92% for epilepsy) and 442 unexposed women were eligible. Rate of fetal MCMs in the unexposed group was 1.1%. In women who received newer AEDs, MCM rates ranged from 2.0% to 4.2%. Relative risk for MCMs was 1.8 with lamotrigine (95% confidence interval, 0.7–4.6), 2.2 with levetiracetam (95% CI, 0.8–6.4), and 3.8 with topiramate (95% CI, 1.4–10.6). For older AEDs, MCM rates ranged from 2.9% to 9.3%. RR was 2.7 with carbamazepine (95% CI, 1.0–7.0), 2.6 with phenytoin (95% CI, 0.9–7.4), and 9.0 with valproate (95% CI, 3.4–23.3). Valproate was the only AED that showed a dose–response relation.

Comment: Although the confidence intervals associated with these findings are relatively wide, women with epilepsy who require anti seizure medication during pregnancy should find these results reassuring. For most antiepileptic drugs other than valproate, rates of major congenital malformations were low. Before conception, it should be determined whether a woman must take an AED during pregnancy. If so, the regimen should be simplified whenever possible to one AED that controls seizures at the lowest possible dose. For those women with epilepsy who are not planning to become pregnant, reliable contraception is critical.

Source: Journal Watch Women’s Health

Depression and AF in Women: Don’t Worry, Be Happy.


Psychological distress was not linked to atrial fibrillation in the Women’s Health Study.

Stress is frequently blamed for cardiac disease, and depression has been associated with sudden cardiac death (JW Cardiol Jun 10 2005). However, whether negative affect is linked to atrial fibrillation (AF) is not clear. The Women’s Health Study included 39,876 women free of cardiovascular disease who were randomized to receive vitamin E, low-dose aspirin, both, or neither for primary prevention of cancer and cardiovascular disease. Of these, 30,746 with adequate follow-up and complete Mental Health Inventory-5 data were included in the present analysis.

During a median follow-up of 125 months, 2089 (6.8%) women reported substantial psychological distress, and 771 (2.5%) had new-onset AF. Neither global psychological distress nor depression was associated with AF. A post-hoc analysis showed a significant decrease in AF risk in women who reported feeling happy some or most of the time.

Comment: Contrary to popular belief, stress is not the source of all ills. In prior studies, depressive symptoms have been associated with myocardial infarction as well as sudden cardiac death, but not with atrial fibrillation, and according to this study, such an association with AF is unlikely. An editorialist focuses on the exploratory finding that positive affect may be protective against AF. The bottom line: Stay happy if you can — but even if you can’t, don’t worry about AF.

Source: Journal Watch Cardiology

What exactly is the Higgs boson? Have physicists proved that it really exists?


Stephen Reucroft in the Elementary Particle Physics group at Northeastern University gives this introductory reply:

“Over the past few decades, particle physicists have developed an elegant theoretical model (the Standard Model) that gives a framework for our current understanding of the fundamental particles and forces of nature. One major ingredient in this model is a hypothetical, ubiquitous quantum field that is supposed to be responsible for giving particles their masses (this field would answer the basic question of why particles have the masses they do–or indeed, why they have any mass at all). This field is called the Higgs field. As a consequence of wave-particle duality, all quantum fields have a fundamental particle associated with them. The particle associated with the Higgs field is called the Higgs boson.

“Because the Higgs field would be responsible for mass, the very fact that the fundamental particles do have mass is regarded by many physicists as an indication of the existence of the Higgs field. We can even take all our data on particle physics data and interpret them in terms of the mass of a hypothetical Higgs boson. In other words, if we assume that the Higgs boson exists, we can infer its mass based on the effect it would have on the properties of other particles and fields. We have not yet truly proved that the Higgs boson exists, however. One of the main aims of particle physics over the next couple of decades is to prove once and for all the existence or nonexistence of the Higgs boson.”

Another, more extensive response comes from Howard Haber and Michael Dine, both of whom are professors of physics at the Santa Cruz Institute for Particle Physics at the University of California at Santa Cruz:

“Much of today’s research in elementary particle physics focuses on the search for a particle called the Higgs boson. This particle is the one missing piece of our present understanding of the laws of nature, known as the Standard Model. This model describes three types of forces: electromagnetic interactions, which cause all phenomena associated with electric and magnetic fields and the spectrum of electromagnetic radiation; strong interactions, which bind atomic nuclei; and the weak nuclear force, which governs beta decay–a form of natural radioactivity–and hydrogen fusion, the source of the sun’s energy. (The Standard Model does not describe the fourth force, gravity.)

“In our daily lives, electromagnetism is the most familiar of these forces. Until relatively recently, it was the only one which we understood well. Since the 1970s, however, scientists have come to understand the strong and weak forces almost equally well. In the past few years, in high-energy experiments at CERN, the European laboratory for particle physics, near Geneva and at the Stanford Linear Accelerator Center (SLAC), physicists have made precision tests of the Standard Model. It seems to provide a complete description of the natural world down to scales on the order of one- thousandth the size of an atomic nucleus.

“The Higgs particle is connected with the weak force. Electromagnetism describes particles interacting with photons, the basic units of the electromagnetic field. In a parallel way, the modern theory of weak interactions describes particles (the W and Z particles) interacting with electrons, neutrinos, quarks and other particles. In many respects, these particles are similar to photons. But they are also strikingly different. The photon probably has no mass at all. From experiments, we know that a photon can be no more massive than a thousand-billion-billion-billionth (10 -30) the mass of an electron, and for theoretical reasons, we believe it has exactly zero mass. The W and Z particles, however, have enormous masses: more than 80 times the mass of a proton, one of the constituents of an atomic nucleus.

“The huge masses of the W and Z particles is a puzzle. If one simply postulates that these particles interact with the known elementary particles and have a large mass, the theory is inconsistent. ( For example, the Standard Model would predict that the probability of two particles having very high energies colliding with one another would be greater than one, a physical impossibility!) To fix this problem, there must be additional particles. The simplest models that explain the masses of the W and Z have only one such particle: the Higgs boson. There are also other proposals, many of them more exotic. For instance, there may be several Higgs bosons, entirely new types of strong interactions and a possible new fundamental physical symmetry, called supersymmetry.

“If there is a Higgs boson whose mass is less than that of the Z particle, physicists will discover it over the next two years at the large accelerator in Geneva known as LEP (the Large Electron Positron collider). LEP accelerates electrons and their antimatter twins (positrons) to very high energies, then allows them to collide. If Higgs bosons have larger masses, they might be unveiled at the Fermi National Accelerator Laboratory in Batavia, Ill., by the turn of the century. Otherwise we are very likely to find them at a new accelerator, LHC (the Large Hadron Collider), scheduled to start operation at CERN in 2005. Discovery of the Higgs boson was one of the principal tasks scheduled for the Superconducting Super Collider, which the U.S. Congress canceled in 1993.

“In sum, the Higgs boson is a critical ingredient to complete our current understanding of the Standard Model, the theoretical edifice of particle physics. Different types of Higgs bosons, if they exist, may lead us into new realms of physics beyond the Standard Model.”

And Chris Quigg, a researcher in the theoretical physics department at Fermi National Accelerator Laboratory, presents a deep overview:

“The central challenge in particle physics today is to understand what differentiates electromagnetism from the weak interactions that govern radioactivity and the energy output of the sun. The fundamental interactions between particles derive from symmetries that we have observed in nature.

“One of the great recent achievements of modern physics is a quantum field theory in which weak and electromagnetic interactions are understood to arise from a common symmetry. This ‘electroweak theory’ has been validated in detail, especially by experiments in the LEP Collider at CERN. Although the weak and electromagnetic interactions are linked through symmetry, their manifestations in the everyday world are very different. The influence of electromagnetism extends to infinite distances, whereas the influence of the weak interaction is confined to subnuclear dimensions, less than about 10-15 centimeters. This difference is directly related to the fact that the photon, the force carrier of electromagnetism, is massless, whereas the W and Z particles, which carry the weak forces, are about 100 times the mass of the proton.

“What hides the symmetry between the weak and electromagnetic interactions? That is the question we hope to answer through experiments at the Large Hadron Collider (LHC) at CERN. When the LHC is commissioned, around the year 2005, it will enable us to study collisions among quarks at energies approaching 1 TeV, or a trillion (1012) electron volts. A thorough exploration of the 1-TeV energy scale will determine the mechanism by which the electroweak symmetry is hidden and teach us what makes the W and Z particles massive.

“The simplest guess goes back to theoretical work by British physicist Peter Higgs and others in the 1960s. According to this picture, the giver of mass is a neutral particle with zero spin that we call the Higgs boson. In today’s version of the electroweak theory, the W and Z particles and all the fundamental constituents–quarks and leptons–get their masses by interacting with the Higgs boson. But the Higgs boson remains hypothetical; it has not been observed. That is why particle physicists often use the search for the Higgs boson as a shorthand for the campaign to learn the agent that hides electroweak symmetry and endows other particles with mass.

“If the answer is the Higgs boson, we can say enough about its properties to guide the search. Unfortunately, the electroweak theory does not predict the mass of the Higgs boson, although consistency arguments require that it have a mass of less than 1 TeV. Experimental searches already carried out tell us that the Higgs must weigh more than about 60 billion electron volts (GeV), or 0.06 TeV.

“If the Higgs is relatively light, it may be seen soon in electron- positron annihilations at LEP, produced in association with the Z. The Higgs boson would decay into a b quark and a b antiquark. In a few years, experiments at Fermilab’s Tevatron should be able to extend the search to higher masses, looking for Higgs plus W or Higgs plus Z particles in collisions between protons and antiprotons. If the Higgs mass exceeds about 130 GeV, our best hope lies with the LHC. Higher-energy electron-positron colliders, or even muon colliders, could also play an important role.

“Our inability to predict the mass of the Higgs boson is one of the reasons many of us believe that this picture cannot tell the whole story. We are searching for extensions to the electroweak theory that make it more coherent and more predictive. Two of these seem promising. Both of them imply that we will find a rich harvest of new particles and new phenomena at the high energies we are just beginning to explore at Fermilab and CERN. One approach is a generalization of the electroweak theory, called supersymmetry, that associates new particles with all the known quarks and leptons and force particles. Supersymmetry entails several Higgs bosons, and one of which probably lies in the energy regime that LEP is starting to survey. In the other approach, called dynamical symmetry breaking, the Higgs boson is not an elementary particle but a composite whose properties we may hope to compute once we understand its constituents and their interactions.

“Over the next 15 years, we should begin to find a real understanding of the origin of mass. The interest lies not just in the arcana of accelerator experiments but suffuses everything in the world around us: mass is what determines the range of forces and sets the scale of all the structures we see in nature.

“In 1993 British Science Minister William Waldegrave challenged particle physicists to explain on a single page what the Higgs boson is and why they are so eager to find it. He awarded bottles of champagne to the authors of five winning entries at the annual meeting of the British Association for the Advancement of Science. The prizewinning papers range from serious to whimsical. They appeared in the September 1993 issue of Physics World, the monthly magazine of the British Institute of Physics, and are available online.

Source: Scientific American.

A QUANTUM LEAP.


The discovery of the puts our understanding of nature on a new firm footing

Who would have believed it? Every now and then theoretical speculation anticipates experimental observation in physics. It doesn’t happen often, in spite of the romantic notion of theorists sitting in their rooms alone at night thinking great thoughts. Nature usually surprises us. But today, two separate experiments at the Large Hadron Collider of the European Center for Nuclear Research (CERN) in Geneva reported convincing evidence for the long sought-after “Higgs” particle, first proposed to exist almost 50 years ago and at the heart of the “standard model” of elementary particle physics—the theoretical formalism that describes three of the four known forces in nature, and which to date agrees with every experimental observation done to date.

The LHC is the most complex (and largest) machine that humans have ever built, requiring thousands of physicists from dozens of countries, working full time for a decade to build and operate. And even with 26 kilometers of tunnel, accelerating two streams of protons in opposite directions at more than 99.9999 percent the speed of light and smashing them together in spectacular collisions billions of times each second, producing hundreds of particles in each collision; two detectors the size of office buildings to measure the particles; and a bank of more than 3,000 computers analyzing the events in real time in order to search for something interesting, the Higgs particle itself never directly appears.

Like the proverbial Cheshire cat, the Higgs instead leaves only a smile, by which I mean it decays into other particles that can be directly observed. After a lot of work and computer time, one can follow all the observed particles backward and determine the mass and other properties of the invisible Higgs candidates.

I say candidates, because so far each of the two major LHC experimental collaborations has claimed to discover a new particle with properties consistent with the other, and consistent with the general predictions of the standard model, which suggests that the Higgs particle should be produced at a rate comparable to the rate observed and should decay into the specific combinations of known elementary particles that are observed. They are being very conservative. One can in fact quantify the likelihood that the observations are mistaken and that the events are actually background noise mimicking a real signal. Each experiment quotes a likelihood of very close to “5 sigma,” meaning the likelihood that the events were produced by chance is less than one in 3.5 million. Yet in spite of this, the only claim that has been made so far is that the new particle is real and “Higgs-like.”  The existing data set is still too small to statistically determine with precise accuracy that the data is consistent with standard model.

This cautious approach is actually a good thing, because it leaves open the possibility that the particle being observed is not exactly the simple Higgs particle of the standard model. Instead, it may point the way toward understanding whatever new physics underlies the standard model—and perhaps explain outstanding mysteries from the question of why the universe is made of matter and not antimatter, to whether our universe is unique.

The idea of the Higgs particle was proposed nearly 50 years ago. (Incidentally, it has never been called the “God particle” by the physics community. That moniker has been picked up by the media, and I hope it goes away.) It was discussed almost as a curiosity, to get around some inconsistencies between predictions and theory at the time in particle physics, that if an otherwise invisible background field exists permeating empty space throughout the universe, then elementary particles can interact with this field. Even if they initially have no mass, they will encounter resistance to their motion through their interactions with this field, and they will slow down. They will then act like they have mass. It is like trying to push your car off the road if it has run out of gas. You and a friend can roll it along as long as it is on the road, but once it goes off and the wheels encounter mud, you and a whole gang of friends who may have been sitting in the back seat cannot get it moving. The car acts heavier.

Within a few years, it had been recognized that this phenomenon could not only explain why elementary particles like the particles that make up our bodies have the masses they do, but it could also illuminate why two of the four known forces in nature, electromagnetism and the so-called “weak” force (responsible for the processes that power the sun), which on the surface appear very different at the scales we measure, are actually at a fundamental scale merely different manifestations of a single force, now called the “electro-weak” force.

All of the predictions based on these ideas have turned out to be in accord with experiment. But there was one major thing missing: What about the invisible field? How could we tell if it really exists? It turns out that in particle physics, for every field in nature, like the electromagnetic field, there must exist an elementary particle that can be produced if one has sufficient energy to create it. So, the background field, known as a Higgs field, must be associated with a Higgs particle.

In the 1990s in the United States, a gigantic machine called the Superconducting Super Collider was being built (involving the largest tunnel ever dug—some 60 miles in circumference) to search for the Higgs—and the origin of mass. But Congress, in its infinite wisdom (Congress seems to have gotten no wiser since), decided that the country couldn’t afford the $5 billion to $10 billion that had already been approved by three different presidents. Back then, $5 billion was a lot of money! So, the LHC was constructed in Geneva by a group of European countries, and the rest is history, or will be.

The discovery announced today in Geneva represents a quantum leap (literally) in our understanding of nature at its fundamental scale, and the culmination of a half-century of dedicated work by tens of thousands of scientists using technology that has been invented for the task, and it should be celebrated on these accounts alone.

But I find it particularly exciting for two reasons—one scientific, the other more personal. First, the standard model, as remarkably successful as it has been, leaves open more questions than it answers. What causes the Higgs field to exist throughout space today? Are there other forces that dynamically determine its configuration? Why doesn’t the same phenomenon that causes the Higgs particle to exist at the mass it does cause gravity and the other forces in nature to behave similarly? Over the past 40 years or so, a host of theoretical speculations have been developed to answer these questions. But like those who are sensorially deprived, we may just be hallucinating. The cold water of experiment may now wash away many of our wrong ideas and, perhaps more importantly, could point us in the right direction. In the process I expect what we will discover about the universe may currently be beyond our wildest dreams.

More than this, however, the Higgs field implies that otherwise seemingly empty space is much richer and weirder than we could have imagined even a century ago, and in fact that we cannot understand our own existence without understanding “emptiness” better. Readers of mine will know that as a physicist, I have been particularly interested in “nothing” in all of its forms and its relation to something—namely us. The discovery of the Higgs says that “nothing” is getting ever more interesting.

Source: Slate.com

Transmissible strains of Pseudomonas aeruginosa in cystic fibrosis lung infections.


Pseudomonas aeruginosa chronic lung infections are the major cause of morbidity and mortality associated with cystic fibrosis. For many years, the consensus was that cystic fibrosis patients acquire P. aeruginosa from the environment, and hence harbour their own individual clones. However, in the past 15 yrs the emergence of transmissible strains, in some cases associated with greater morbidity and increased antimicrobial resistance, has changed the way that many clinics treat their patients. Here we provide a summary of reported transmissible strains in the UK, other parts of Europe, Australia and North America. In particular, we discuss the prevalence, epidemiology, unusual genotypic and phenotypic features, and virulence of the most intensively studied transmissible strain, the Liverpool epidemic strain. We also discuss the clinical impact of transmissible strains, in particular the diagnostic and infection control approaches adopted to counter their spread. Genomic analysis carried out so far has provided little evidence that transmissibility is due to shared genetic characteristics between different strains. Previous experiences with transmissible strains should help us to learn lessons for the future. In particular, there is a clear need for strain surveillance if emerging problem strains are to be detected before they are widely transmitted.

Source: European Respiratory Journal

Prognosis of acute respiratory distress syndrome in neutropenic cancer patients.


To date, no study has been specifically designed to identify determinants of death in neutropenic cancer patients presenting with acute respiratory distress syndrome (ARDS). The aim of this study was to identify early predictive factors of 28-day mortality in these patients. Factors associated with 28-day mortality during intensive care unit (ICU) stay were also described.

70 consecutive cancer patients with ARDS and neutropenia were prospectively analysed over a 6-yr period.

Mortality at 28 days was 63%. Factors independently associated with good prognosis were: lobar ARDS (OR 0.10, 95% CI 0.02–0.48), use of initial antibiotic treatment active on difficult to treat bacteria (ticarcillin-resistant Pseudomonas aeruginosa, Stenotrophomonas maltophilia or extended-spectrum β-lactamase-producing strains) (OR 0.08, 95% CI 0.02–0.33) and first-line chemotherapy (OR 0.08, 95% CI 0.02–0.37). During the ICU stay, mortality was associated with the markers of organ dysfunctions, the absence of neutropenia recovery and the use of vasopressors. During the first 3 weeks, the conditional probability of discharge alive from ICU did not decrease.

At ICU admission, first-line chemotherapy, lobar ARDS and antibiotic treatment active on difficult-to-treat bacteria were associated with survival. During ICU stay, mortality was associated with organ dysfunctions and use of vasopressors. Most survivors have an ICU stay of >3 weeks.

Source: European Respiratory Journal

 

 

Massive monoclonal expansion of CD4 T-cells specific for a Mycobacterium tuberculosis ESAT-6 peptide.


T-cell responses towards tuberculin (purified protein derivative; PPD) or the Mycobacterium tuberculosis-specific antigens early secretory antigenic target (ESAT)-6 and culture filtrate protein-10 are indicative of prior contact with mycobacterial antigens. In this study, we investigated the exceptional case of a 75-yr-old patient who devoted more than one-third of his CD4 T-cells against PPD and ESAT-6.

Antigen-specific T-cells were characterised using flow cytometric intracellular cytokine staining, ELISPOT assay, proliferation assays, and T-cell receptor spectratyping.

T-cell frequencies were far above those found in age-matched controls (median 0.33%, range 0.05–6.32%) and remained at high levels for >2 yrs. The patient initially presented with haemoptysis, but active tuberculosis was ruled out by repeated analysis of sputum and bronchoalveolar lavage fluid. Skin testing was negative and haemoptyses did not have a M. tuberculosis-related aetiology. Phenotypical and functional properties of specific T-cells were consistent with a terminally differentiated effector-memory phenotype with capacity to produce interferon-γ, interleukin-2 and tumour necrosis factor-α. Epitope mapping showed that the CD4 T-cells were directed against a single peptide from ESAT-6 (amino acid 5–20) that was presented in context of HLA-DR. T-cell receptor Vβ-spectratyping and sequencing of specific CD4 T-cells revealed a prominent peak fraction of monoclonal origin.

In conclusion, similar to monoclonal gammopathies of undetermined significance, this may represent the first T-cell counterpart with known specificity against M. tuberculosis.

Source: European Respiratory Journal

 

 

Inhibitory effects of tiotropium on rhinovirus infection in human airway epithelial cells.


Infection by rhinoviruses (RVs) causes exacerbations of chronic obstructive pulmonary disease (COPD). The long-acting anti-cholinergic agent tiotropium reduces the frequency of COPD exacerbations, but the inhibitory effects of tiotropium on the COPD exacerbations induced by RVs are unclear. Likewise, the effects of tiotropium on RVs infection remain to be studied.

To examine the effects of tiotropium on RV infection and RV infection-induced airway inflammation, human tracheal epithelial cells were infected with a major group RV, type 14 RV (RV14).

RV14 infection increased the viral titre and the amount of pro-inflammatory cytokines, including interleukin (IL)-1β and -6, in supernatant fluids and the amount of RV14 RNA in cells. Tiotropium reduced RV14 titres, RNA and cytokine concentrations, and susceptibility to RV14 infection. Tiotropium reduced the expression of intercellular adhesion molecule (ICAM)-1, the receptor for RV14, and the number of cellular acidic endosomes, which allow RV14 RNA to enter the cytoplasm. Tiotropium inhibited the activation of nuclear factor-κB proteins, including p50 and p65, in the nuclear extracts, and it increased the cytosolic amount of inhibitory κB-α.

Tiotropium may inhibit RV14 infection by reducing the levels of ICAM-1 and acidic endosomes and may also modulate airway inflammation in rhinovirus infection.

Source: European Respiratory Journal