939 research outputs found
Kinetic models with randomly perturbed binary collisions
We introduce a class of Kac-like kinetic equations on the real line, with
general random collisional rules, which include as particular cases models for
wealth redistribution in an agent-based market or models for granular gases
with a background heat bath. Conditions on these collisional rules which
guarantee both the existence and uniqueness of equilibrium profiles and their
main properties are found. We show that the characterization of these
stationary solutions is of independent interest, since the same profiles are
shown to be solutions of different evolution problems, both in the econophysics
context and in the kinetic theory of rarefied gases
Single strain high-depth ngs reveals high rdna (Its-lsu) variability in the four prevalent pathogenic species of the genus candida
Ribosomal RNA in fungi is encoded by a series of genes and spacers included in a large operon present in 100 tandem repeats, normally in a single locus. The multigene nature of this locus was somehow masked by Sanger sequencing, which produces a single sequence reporting the prevalent nucleotide of each site. The introduction of next generation sequencing led to deeper knowledge of the individual sequences (reads) and therefore of the variants between the same DNA sequences located in different tandem repeats. In this framework, NGS sequencing of the rDNA region was used to elucidate the extent of intra-and inter-genomic variation at both the strain and species level. Specifically, the use of an innovative NGS technique allowed the high-throughput highdepth sequencing of the ITS1-LSU D1/D2 amplicons of 252 strains belonging to four opportunistic yeast species of the genus Candida. Results showed the presence of a large extent of variability among strains and species. These variants were differently distributed throughout the analyzed regions with a higher concentration within the Internally Transcribed Spacer (ITS) region, suggesting that concerted evolution was not able to totally homogenize these sequences. Both the internal variability and the SNPs between strain can be used for a deep typing of the strains and to study their ecology
Abnormal activity in hypothalamus and amygdala during humour processing in human narcolepsy with cataplexy
Narcolepsy with cataplexy (NC) is a complex sleep-wake disorder, which was recently found to be associated with a reduction or loss of hypocretin (HCRT, also called orexin). HCRT is a hypothalamic peptide implicated in the regulation of sleep/wake, motor and feeding functions. Cataplexy refers to episodes of sudden and transient loss of muscle tone triggered by strong, mostly positive emotions, such as hearing or telling jokes. Cataplexy is thought to reflect the recruitment of ponto-medullary mechanisms that normally underlie muscle atonia during REM-sleep. In contrast, the suprapontine brain mechanisms associated with the cataplectic effects of emotions in human narcolepsy with cataplexy remain essentially unknown. Here, we used event-related functional MRI to assess brain activity in 12 NC patients and 12 controls while they watched sequences of humourous pictures. Patients and controls were similar in humour appreciation and activated regions known to contribute to humour processing, including limbic and striatal regions. A direct statistical comparison between patients and controls revealed that humourous pictures elicited reduced hypothalamic response together with enhanced amygdala response in the patients. These results suggest (i) that hypothalamic HCRT activity physiologically modulates the processing of emotional inputs within the amygdala, and (ii) that suprapontine mechanisms of cataplexy involve a dysfunction of hypothalamic-amygdala interactions triggered by positive emotion
Ten Years of Medical Informatics and Standards Support for Clinical Research in an Infectious Diseases Network
Background It is 30 years since evidence-based medicine became a great support for individual clinical expertise in daily practice and scientific research. Electronic systems can be used to achieve the goal of collecting data from heterogeneous datasets and to support multicenter clinical trials. The Ligurian Infectious Diseases Network (LIDN) is a web-based platform for data collection and reuse originating from a regional effort and involving many professionals from different fields. Objectives The objective of this work is to present an integrated system of ad hoc interfaces and tools that we use to perform pseudonymous clinical data collection, both manually and automatically, to support clinical trials. Methods The project comprehends different scenarios of data collection systems, according to the degree of information technology of the involved centers. To be compliant with national regulations, the last developed connection is based on the standard Clinical Document Architecture Release 2 by Health Level 7 guidelines, interoperability is supported by the involvement of a terminology service. Results Since 2011, the LIDN platform has involved more than 8,000 patients from eight different hospitals, treated or under treatment for at least one infectious disease among human immunodeficiency virus (HIV), hepatitis C virus, severe acute respiratory syndrome coronavirus 2, and tuberculosis. Since 2013, systems for the automatic transfer of laboratory data have been updating patients' information for three centers, daily. Direct communication was set up between the LIDN architecture and three of the main national cohorts of HIV-infected patients. Conclusion The LIDN was originally developed to support clinicians involved in the project in the management of data from HIV-infected patients through a web-based tool that could be easily used in primary-care units. Then, the developed system grew modularly to respond to the specific needs that arose over a time span of more than 10 years
SAS CARE 1: Sleep architecture changes in a cohort of patients with Ischemic Stroke/TIA.
OBJECTIVE
Changes in sleep architecture following ischemic stroke have been poorly investigated. Our objective was to explore changes of sleep structure in patients with ischemic stroke or transient ischemic attack in order to verify a possible predictive value of sleep with respect to clinical outcome.
METHODS
Patients recruited in the prospective SAS-CARE study received two polysomnographies (PSG) in the acute and chronic phases after stroke/TIA. Sleep parameters were compared between the two time-points and matched with a non-stroke population randomly selected from the HypnoLaus cohort.
RESULTS
Of the 169 patients investigated with PSG in the acute phase, 104 were again studied 3 months after stroke symptom onset and compared with 162 controls. The acute phase of stroke/TIA was associated with sleep disruption, which significantly improved in the chronic phase, but remained worse than controls (total sleep time improve from 318.8 ± 90.8 to 348.4 ± 81.5 min, compared to 388.2 ± 71.3 in controls, sleep latency from 49.9 ± 58.4 to 27.9 min, compared to 20.2 ± 22 in controls, sleep efficiency from 58.2 ± 18.1% to 27.9 ± 36.4 min, compared to 83.4 ± 10.3% in controls, wakefulness after sleep onset percentage from 36.5 ± 17.3 to 29.3 ± 15.6, compared to 13.2 ± 9.2 in controls). The percentage of REM sleep was negatively associated with stroke severity, whereas stroke topography did not correlate with sleep parameters.
CONCLUSIONS
This study confirmed a severe sleep disruption in the acute phase of stroke. Although a significant improvement of sleep quality was observed during the three months after stroke, sleep architecture did not normalize. In particular, sleep efficiency and REM sleep seem to be particularly affected by stroke in the acute phase, with a relative preservation of NREM sleep. We suggest that these sleep architecture changes represent a persistent marker of brain damage due to stroke. Further studies are needed to assess the relationship with stroke topographic and outcome
Prevalence and management of chronic insomnia in Swiss primary care: Cross-sectional data from the “Sentinella” practice-based research network
We investigated the prevalence and treatment of patients with chronic insomnia presenting to Swiss primary care physicians (PCPs) part of “Sentinella”, a nationwide practice-based research network. Each PCP consecutively asked 40 patients if they had sleep complaints, documented frequency, duration, comorbidities, and reported ongoing treatment. We analysed data of 63% (83/132) of the PCPs invited. The PCPs asked 76% (2,432/3,216) of included patients about their sleep (51% female); 31% (761/2,432) of these had had insomnia symptoms; 36% (875/2,432) had current insomnia symptoms; 11% (269/2,432) met the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for chronic insomnia (61% female). In all, 75% (201/269) of patients with chronic insomnia had comorbidities, with 49% (99/201) reporting depression. Chronic insomnia was treated in 78% (209/269); 70% (188/268) took medication, 38% (102/268) benzodiazepines or benzodiazepine receptor agonists, 32% (86/268) took antidepressants. Only 1% (three of 268) had been treated with cognitive behavioural therapy for insomnia (CBT-I). A third of patients presenting for a non-urgent visit in Swiss primary care reported insomnia symptoms and 11% met the DSM-5 criteria for chronic insomnia. Hypnotics were the most common treatment, but almost no patients received first-line CBT-I. Reducing the burden of insomnia depends on disseminating knowledge about and access to CBT-I, and encouraging PCPs to discuss it with and offer it as a first-line treatment to patients with chronic insomnia
Treating insomnia in Swiss primary care practices: A survey study based on case vignettes
Guidelines recommend cognitive behavioural therapy for insomnia (CBT-I) as first-line treatment for chronic insomnia, but it is not clear how many primary care physicians (PCPs) in Switzerland prescribe this treatment. We created a survey that asked PCPs how they would treat chronic insomnia and how much they knew about CBT-I. The survey included two case vignettes that described patients with chronic insomnia, one with and one without comorbid depression. PCPs also answered general questions about treating chronic insomnia and about CBT-I and CBT-I providers. Of the 820 Swiss PCPs we invited, 395 (48%) completed the survey (mean age 54 years; 70% male); 87% of PCPs prescribed sleep hygiene and 65% phytopharmaceuticals for the patient who had only chronic insomnia; 95% prescribed antidepressants for the patient who had comorbid depression. In each case, 20% of PCPs prescribed benzodiazepines or benzodiazepine receptor agonists, 8% prescribed CBT-I, 68% said they knew little about CBT-I, and 78% did not know a CBT-I provider. In the clinical case vignettes, most PCPs treated chronic insomnia with phytopharmaceuticals and sleep hygiene despite their lack of efficacy, but PCPs rarely prescribed CBT-I, felt they knew little about it, and usually knew no CBT-I providers. PCPs need more information about the benefits of CBT-I and local CBT-I providers and dedicated initiatives to implement CBT-I in order to reduce the number of patients who are prescribed ineffective or potentially harmful medications
Thomson Scattering of Coherent Diffraction Radiation by an Electron Bunch
The paper considers the process of Thomson scattering of coherent diffraction
radiation (CDR) produced by the preceding bunch of the accelerator on one of
the following bunches. It is shown that the yield of scattered hard photons is
proportional to N, where N is the number of electrons per bunch. A
geometry is chosen for the CDR generation and an expression is obtained for the
scattered photon spectrum with regard to the geometry used, that depends in an
explicit form on the bunch size. A technique is proposed for measuring the
bunch length using scattered radiation characteristics.Comment: 14 pages, LATEX, 6 ps.gz figures, submitted to Phys.Rev.
ABCC1: a gateway for pharmacological compounds to the ischaemic brain
By preventing access of drugs to the CNS, the blood-brain barrier hampers developments in brain pharmacotherapy. Strong efforts are currently being made to identify drugs that accumulate more efficaciously in ischaemic brain tissue. We identified an ATP-binding cassette (ABC) transporter, ABCC1, which is expressed on the abluminal surface of the brain capillary endothelium and mildly downregulated in response to focal cerebral ischaemia, induced by intraluminal middle cerebral artery occlusion. In biodistribution studies we show that ABCC1 promotes the accumulation of known neuroprotective and neurotoxic compounds in the ischaemic and non-ischaemic brain, ABCC1 deactivation reducing tissue concentrations by up to two orders of magnitude. As such, ABCC1's expression and functionality in the brain differs from the liver, spleen and testis, where ABCC1 is strongly expressed on parenchymal cells, resulting -- in case of liver and testis -- in directed transport from the tissue into the blood. After focal cerebral ischaemia, ABCC1 deactivation abolished the efficacy of both neuroprotective and neurotoxic compounds. Our data indicate that ABCC1 acts as gateway for pharmacological compounds to the stroke brain. We suggest that the tailoring of compounds binding to abluminal but not luminal ABC transporters may facilitate stroke pharmacotherap
Feedback topology and XOR-dynamics in Boolean networks with varying input structure
We analyse a model of fixed in-degree Random Boolean Networks in which the
fraction of input-receiving nodes is controlled by a parameter gamma. We
investigate analytically and numerically the dynamics of graphs under a
parallel XOR updating scheme. This scheme is interesting because it is
accessible analytically and its phenomenology is at the same time under
control, and as rich as the one of general Boolean networks. Biologically, it
is justified on abstract grounds by the fact that all existing interactions
play a dynamical role. We give analytical formulas for the dynamics on general
graphs, showing that with a XOR-type evolution rule, dynamic features are
direct consequences of the topological feedback structure, in analogy with the
role of relevant components in Kauffman networks. Considering graphs with fixed
in-degree, we characterize analytically and numerically the feedback regions
using graph decimation algorithms (Leaf Removal). With varying gamma, this
graph ensemble shows a phase transition that separates a tree-like graph region
from one in which feedback components emerge. Networks near the transition
point have feedback components made of disjoint loops, in which each node has
exactly one incoming and one outgoing link. Using this fact we provide
analytical estimates of the maximum period starting from topological
considerations
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