476 research outputs found

    The increase of the functional entropy of the human brain with age

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    We use entropy to characterize intrinsic ageing properties of the human brain. Analysis of fMRI data from a large dataset of individuals, using resting state BOLD signals, demonstrated that a functional entropy associated with brain activity increases with age. During an average lifespan, the entropy, which was calculated from a population of individuals, increased by approximately 0.1 bits, due to correlations in BOLD activity becoming more widely distributed. We attribute this to the number of excitatory neurons and the excitatory conductance decreasing with age. Incorporating these properties into a computational model leads to quantitatively similar results to the fMRI data. Our dataset involved males and females and we found significant differences between them. The entropy of males at birth was lower than that of females. However, the entropies of the two sexes increase at different rates, and intersect at approximately 50 years; after this age, males have a larger entropy

    Pneumomediastinum from nasal insufflation of cocaine

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    Chest pain is a common presenting symptom of cocaine users to the emergency department that requires a thorough work up. Pneumomediastinum is an uncommon complication of cocaine abuse that occurs more commonly when cocaine is smoked, but can also occur when cocaine is nasally insufflated. Our case report presents a patient with pneumomediastinum secondary to cocaine insufflation and reviews the necessary diagnostic tests that must be performed to rule out secondary pneumomediastinum, a severe life-threatening condition. Our case is unique, as it is one of a few reported cases of pneumomediastinum occurring after the use of intranasal cocaine

    The impact of the implementation of work hour requirements on residents' career satisfaction, attitudes and emotions

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    BACKGROUND: To assess the impact of work hours' limitations required by the Accreditation Council for Graduate Medical Education (ACGME) on residents' career satisfaction, emotions and attitudes. METHODS: A validated survey instrument was used to assess residents' levels of career satisfaction, emotions and attitudes before and after the ACGME duty hour requirements were implemented. The "pre" implementation survey was distributed in December 2002 and the "post" implementation one in December 2004. Only the latter included work-hour related questions. RESULTS: The response rates were 56% for the 2002 and 72% for the 2004 surveys respectively. Although career satisfaction remained unchanged, numerous changes occurred in both emotions and attitudes. Compared to those residents who did not violate work-hour requirements, those who did were significantly more negative in attitudes and emotions. CONCLUSION: With the implementation of the ACGME work hour limitations, the training experience became more negative for those residents who violated the work hour limits and had a small positive impact on those who did not violate them. Graduate medical education leaders must innovate to make the experiences for selected residents improved and still maintain compliance with the work hour requirements

    Tradeoff between Stability and Maneuverability during Whole-Body Movements

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    Understanding how stability and/or maneuverability affects motor control strategies can provide insight on moving about safely in an unpredictable world. Stability in human movement has been well-studied while maneuverability has not. Further, a tradeoff between stability and maneuverability during movement seems apparent, yet has not been quantified. We proposed that greater maneuverability, the ability to rapidly and purposefully change movement direction and speed, is beneficial in uncertain environments. We also hypothesized that gaining maneuverability comes at the expense of stability and perhaps also corresponds with decreased muscle coactivation.We used a goal-directed forward lean movement task that integrated both stability and maneuverability. Subjects (n = 11) used their center of pressure to control a cursor on a computer monitor to reach a target. We added task uncertainty by shifting the target anterior-posterior position mid-movement. We used a balance board with a narrow beam that reduced the base of support in the medio-lateral direction and defined stability as the probability that subjects could keep the balance board level during the task.During the uncertainty condition, subjects were able to change direction of their anterior-posterior center of pressure more rapidly, indicating that subjects were more maneuverable. Furthermore, medio-lateral center of pressure excursions also approached the edges of the beam and reduced stability margins, implying that subjects were less stable (i.e. less able to keep the board level). On the narrow beam board, subjects increased muscle coactivation of lateral muscle pairs and had greater muscle activity in the left leg. However, there were no statistically significant differences in muscle activity amplitudes or coactivation with uncertainty.These results demonstrate that there is a tradeoff between stability and maneuverability during a goal-directed whole-body movement. Tasks with added uncertainty could help individuals learn to be more maneuverable yet sufficiently stable

    European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia

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    The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR

    Natural variation in life history and aging phenotypes is associated with mitochondrial DNA deletion frequency in Caenorhabditis briggsae

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    <p>Abstract</p> <p>Background</p> <p>Mutations that impair mitochondrial functioning are associated with a variety of metabolic and age-related disorders. A barrier to rigorous tests of the role of mitochondrial dysfunction in aging processes has been the lack of model systems with relevant, naturally occurring mitochondrial genetic variation. Toward the goal of developing such a model system, we studied natural variation in life history, metabolic, and aging phenotypes as it relates to levels of a naturally-occurring heteroplasmic mitochondrial <it>ND5 </it>deletion recently discovered to segregate among wild populations of the soil nematode, <it>Caenorhabditis briggsae</it>. The normal product of <it>ND5 </it>is a central component of the mitochondrial electron transport chain and integral to cellular energy metabolism.</p> <p>Results</p> <p>We quantified significant variation among <it>C. briggsae </it>isolates for all phenotypes measured, only some of which was statistically associated with isolate-specific <it>ND5 </it>deletion frequency. We found that fecundity-related traits and pharyngeal pumping rate were strongly inversely related to <it>ND5 </it>deletion level and that <it>C. briggsae </it>isolates with high <it>ND5 </it>deletion levels experienced a tradeoff between early fecundity and lifespan. Conversely, oxidative stress resistance was only weakly associated with <it>ND5 </it>deletion level while ATP content was unrelated to deletion level. Finally, mean levels of reactive oxygen species measured <it>in vivo </it>showed a significant non-linear relationship with <it>ND5 </it>deletion level, a pattern that may be driven by among-isolate variation in antioxidant or other compensatory mechanisms.</p> <p>Conclusions</p> <p>Our findings suggest that the <it>ND5 </it>deletion may adversely affect fitness and mitochondrial functioning while promoting aging in natural populations, and help to further establish this species as a useful model for explicit tests of hypotheses in aging biology and mitochondrial genetics.</p

    Comparison of sapwood invasion by three Phytophthora spp.in different hosts

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    Many Phytophthora spp. have recently been isolated from native vegetation in Western Australia. As their pathogenicity is often unknown, it is not possible to provide advice to land managers on the impact of site infestation on native plants and how these infestations should be managed. We describe a rapid screening method based on sapwood invasion that has been used to compare the pathogenicity of Phytophthora arenaria, P. cinnamomi and P. multivora. Radial invasion into the xylem of six banksias and three eucalypts was assessed in an excised branch assay in summer and winter. Branches were wound inoculated and invasion was assessed by plating from a strip of tissue cut across the stem at the inoculation point and at 40 mm above and below. A symptomless infection had established in both the bark and sapwood within 6 days. P. arenaria was only isolated from the strip of tissue at the inoculation point. P. cinnamomi was isolated from the sapwood of Banksia attenuata, B. burdettii, B. menziesii and B. speciosa 40 mm above or below the inoculation point in some experiments. P. multivora was isolated from B. speciosa 40 mm below the inoculation point in one experiment. Hyphae of both species were seen in both ray parenchyma cells and xylem vessels. The invasiveness of the Phytophthora spp. was compared on the two groups of hosts using scores for sapwood invasion at the inoculation point. For banksias, P. cinnamomi and P. multivora had significantly higher invasion scores on banksias than P. arenaria but were not significantly different to one another. There was no significant difference between the three Phytophthora spp. on the eucalypt hosts. Assessing sapwood invasion provides a rapid, inexpensive and biologically meaningful way of screening the many Phytophthora spp. that have been isolated from native vegetation

    Primary chemotherapy with adriamycin, cisplatin, vincristine and cyclophosphamide in locally advanced thymomas: a single institution experience

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    From 1990 to 1997, 16 consecutive patients with stage III and IVa invasive thymoma were treated in a single institution with primary chemotherapy consisting in adriamycin (40 mg m–2), cisplatin (50 mg m–2) administered intravenously on day 1, vincristine (0.6 mg m–2) on day 2 and cyclophosphamide (700 mg m–2) on day 4 (ADOC). The courses were repeated every 3 weeks. The aim was to evaluate the impact of this cytotoxic regimen with respect to response rate, per cent of patients radically resected, time to progression and overall survival. Two complete responses (one clinical and one pathological) and 11 partial responses were observed (overall response rate 81.2%); two patients had stable disease and one progressed. Toxicity was mild as only two patients developed grade III/IV neutropenia and one patient grade III nausea/vomiting. Nine patients were radically resected (five out of ten with stage III, and four out of six with stage IVa). Median time to progression and overall survival was 33.2 and 47.5 months respectively. Three patients were alive and disease free after more than 5 years. The ADOC scheme is highly active and manageable in the treatment of locally advanced thymoma. As a preoperative approach it should be offered to patients not amenable to surgery or to those surgically resectable but with a great deal of morbidity. © 1999 Cancer Research Campaig
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