Extinction times in the subcritical stochastic SIS logistic epidemic

Many real epidemics of an infectious disease are not straightforwardly super- or sub-critical, and the understanding of epidemic models that exhibit such complexity has been identified as a priority for theoretical work. We provide insights into the near-critical regime by considering the stochastic SIS logistic epidemic, a well-known birth-and-death chain used to model the spread of an epidemic within a population of a given size $N$. We study the behaviour of the process as the population size $N$ tends to infinity. Our results cover the entire subcritical regime, including the "barely subcritical" regime, where the recovery rate exceeds the infection rate by an amount that tends to 0 as $N \to \infty$ but more slowly than $N^{-1/2}$. We derive precise asymptotics for the distribution of the extinction time and the total number of cases throughout the subcritical regime, give a detailed description of the course of the epidemic, and compare to numerical results for a range of parameter values. We hypothesise that features of the course of the epidemic will be seen in a wide class of other epidemic models, and we use real data to provide some tentative and preliminary support for this theory.Comment: Revised; 34 pages; 6 figure

What questions do patients undergoing lower extremity joint replacement surgery have?

BACKGROUND: The value of the Internet to deliver preoperative education would increase if there was variability in questions patients want answered. This study's goal was to have patients consulting an orthopedic surgeon about undergoing either a total hip arthroplasty (THA) or a total knee arthroplasty (TKA) rate the importance of different questions concerning their care. METHODS: We assembled questions patients might have about joint replacement surgery by analyzing the literature and querying a pilot group of patients and surgeons. Twenty-nine patients considering undergoing THA and 19 patients considering TKR completed a written survey asking them to rate 30 different questions, with a 5 point Likert scale from 1 (least important) – 5 (most important). RESULTS: For patients considering THA or TKR, the 4 highest rated questions were: Will the surgery affect my abilities to care for myself?, Am I going to need physical therapy?, How mobile will I be after my surgery?, When will I be able to walk normally again? The mean percentage disagreement was 42% for questions answered by TKR patients and 47% for the THA group. Some patients gave a high rating to questions lowly rated by the rest of the group. CONCLUSIONS: Although there was enough agreement to define a core set of questions that should be addressed with most patients considering THA or TKA, some of the remaining questions were also highly important to some patients. The Web may offer a flexible medium for accommodating this large variety of information needs

Supervised team management, with or without structured psychotherapy, in heavy users of a mental health service with borderline personality disorder: a two-year follow-up preliminary randomized study

<p>Abstract</p> <p>Background</p> <p>Individuals affected by severe Borderline Personality Disorder (BPD) are often heavy users of Mental Health Services (MHS). Short-term treatments currently used in BPD therapy are useful to target disruptive behaviors but they are less effective in reducing heavy MHS use. Therefore, alternative short-term treatments, less complex than long-term psychodynamic psychotherapies but specifically oriented to BPD core problems, need to be developed to reduce MHS overuse. This study aimed to evaluate the efficacy of adding Sequential Brief Adlerian Psychodynamic Psychotherapy (SB-APP) to Supervised Team Management (STM) in BPD treatment compared to STM alone in a naturalistic group of heavy MHS users with BPD. Effectiveness was evaluated 6 times along a two-year follow-up.</p> <p>Methods</p> <p>Thirty-five outpatients who met inclusion criteria were randomly assigned to two treatment groups (STM = 17; SB-APP = 18) and then compared. Clinical Global Impression (CGI) and CGI-modified (CGI-M) for BPD, Global Assessment of Functioning (GAF), State-Trait Anger Expression Inventory (STAXI), and Symptom Checklist-90 Revised (SCL-90-R) were administered at T1, T3, T6, T12, T18 and T24. At T12 the Working Alliance Inventory-Short Form (WAI-S) was also completed. At the one-year follow-up, SB-APP group did not receive any additional individual psychological support. MHS team was specifically trained in BPD treatment and had regular supervisions.</p> <p>Results</p> <p>All patients improved on CGI, GAF, and STAXI scores after 6 and 12 months, independently of treatment received. SB-APP group showed better outcome on impulsivity, suicide attempts, chronic feelings of emptiness, and disturbed relationships. We found a good stabilization at the one year follow-up, even after the interruption of brief psychotherapy in the SB-APP group.</p> <p>Conclusions</p> <p>Although STM for BPD applied to heavy MHS users was effective in reducing symptoms and improving their global functioning, adding a time-limited and focused psychotherapy was found to achieve a better outcome. In particular, focusing treatment on patients' personality with a specific psychotherapeutic approach (i.e. SB-APP) seemed to be more effective than STM alone.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT1356069">NCT1356069</a></p

The Role of CyaY in Iron Sulfur Cluster Assembly on the E. coli IscU Scaffold Protein

Progress in understanding the mechanism underlying the enzymatic formation of iron-sulfur clusters is difficult since it involves a complex reaction and a multi-component system. By exploiting different spectroscopies, we characterize the effect on the enzymatic kinetics of cluster formation of CyaY, the bacterial ortholog of frataxin, on cluster formation on the scaffold protein IscU. Frataxin/CyaY is a highly conserved protein implicated in an incurable ataxia in humans. Previous studies had suggested a role of CyaY as an inhibitor of iron sulfur cluster formation. Similar studies on the eukaryotic proteins have however suggested for frataxin a role as an activator. Our studies independently confirm that CyaY slows down the reaction and shed new light onto the mechanism by which CyaY works. We observe that the presence of CyaY does not alter the relative ratio between [2Fe2S]2+ and [4Fe4S]2+ but directly affects enzymatic activity

Improved management of lysosomal glucosylceramide levels in a mouse model of type 1 Gaucher disease using enzyme and substrate reduction therapy

Gaucher disease is caused by a deficiency of the lysosomal enzyme glucocerebrosidase (acid βâ glucosidase), with consequent cellular accumulation of glucosylceramide (GLâ 1). The disease is managed by intravenous administrations of recombinant glucocerebrosidase (imiglucerase), although symptomatic patients with mild to moderate type 1 Gaucher disease for whom enzyme replacement therapy (ERT) is not an option may also be treated by substrate reduction therapy (SRT) with miglustat. To determine whether the sequential use of both ERT and SRT may provide additional benefits, we compared the relative pharmacodynamic efficacies of separate and sequential therapies in a murine model of Gaucher disease (D409V/null). As expected, ERT with recombinant glucocerebrosidase was effective in reducing the burden of GLâ 1 storage in the liver, spleen, and lung of 3â monthâ old Gaucher mice. SRT using a novel inhibitor of glucosylceramide synthase (Genzâ 112638) was also effective, albeit to a lesser degree than ERT. Animals administered recombinant glucocerebrosidase and then Genzâ 112638 showed the lowest levels of GLâ 1 in all the visceral organs and a reduced number of Gaucher cells in the liver. This was likely because the additional deployment of SRT following enzyme therapy slowed the rate of reaccumulation of GLâ 1 in the affected organs. Hence, in patients whose disease has been stabilized by intravenously administered recombinant glucocerebrosidase, orally administered SRT with Genzâ 112638 could potentially be used as a convenient maintenance therapy. In patients naïve to treatment, ERT followed by SRT could potentially accelerate clearance of the offending substrate.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147062/1/jimd0281.pd

Metabolic Profiling Reveals Distinct Variations Linked to Nicotine Consumption in Humans — First Results from the KORA Study

Exposure to nicotine during smoking causes a multitude of metabolic changes that are poorly understood. We quantified and analyzed 198 metabolites in 283 serum samples from the human cohort KORA (Cooperative Health Research in the Region of Augsburg). Multivariate analysis of metabolic profiles revealed that the group of smokers could be clearly differentiated from the groups of former smokers and non-smokers. Moreover, 23 lipid metabolites were identified as nicotine-dependent biomarkers. The levels of these biomarkers are all up-regulated in smokers compared to those in former and non-smokers, except for three acyl-alkyl-phosphatidylcholines (e.g. plasmalogens). Consistently significant results were further found for the ratios of plasmalogens to diacyl-phosphatidylcolines, which are reduced in smokers and regulated by the enzyme alkylglycerone phosphate synthase (alkyl-DHAP) in both ether lipid and glycerophospholipid pathways. Notably, our metabolite profiles are consistent with the strong down-regulation of the gene for alkyl-DHAP (AGPS) in smokers that has been found in a study analyzing gene expression in human lung tissues. Our data suggest that smoking is associated with plasmalogen-deficiency disorders, caused by reduced or lack of activity of the peroxisomal enzyme alkyl-DHAP. Our findings provide new insight into the pathophysiology of smoking addiction. Activation of the enzyme alkyl-DHAP by small molecules may provide novel routes for therapy

What Is Stochastic Resonance? Definitions, Misconceptions, Debates, and Its Relevance to Biology

Stochastic resonance is said to be observed when increases in levels of unpredictable fluctuations—e.g., random noise—cause an increase in a metric of the quality of signal transmission or detection performance, rather than a decrease. This counterintuitive effect relies on system nonlinearities and on some parameter ranges being “suboptimal”. Stochastic resonance has been observed, quantified, and described in a plethora of physical and biological systems, including neurons. Being a topic of widespread multidisciplinary interest, the definition of stochastic resonance has evolved significantly over the last decade or so, leading to a number of debates, misunderstandings, and controversies. Perhaps the most important debate is whether the brain has evolved to utilize random noise in vivo, as part of the “neural code”. Surprisingly, this debate has been for the most part ignored by neuroscientists, despite much indirect evidence of a positive role for noise in the brain. We explore some of the reasons for this and argue why it would be more surprising if the brain did not exploit randomness provided by noise—via stochastic resonance or otherwise—than if it did. We also challenge neuroscientists and biologists, both computational and experimental, to embrace a very broad definition of stochastic resonance in terms of signal-processing “noise benefits”, and to devise experiments aimed at verifying that random variability can play a functional role in the brain, nervous system, or other areas of biology