131 research outputs found

    Systematic shifts in the balance of excitation and inhibition coordinate the activity of axial motor pools at different speeds of locomotion

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    An emerging consensus from studies of axial and limb networks is that different premotor populations are required for different speeds of locomotion. An important but unresolved issue is why this occurs. Here, we perform voltage-clamp recordings from axial motoneurons in larval zebrafish during “fictive” swimming to test the idea that systematic differences in the biophysical properties of axial motoneurons are associated with differential tuning in the weight and timing of synaptic drive, which would help explain premotor population shifts. We find that increases in swimming speed are accompanied by increases in excitation preferentially to lower input resistance (Rin) motoneurons, whereas inhibition uniformly increases with speed to all motoneurons regardless of Rin. Additionally, while the timing of rhythmic excitatory drive sharpens within the pool as speed increases, there are shifts in the dominant source of inhibition related to Rin. At slow speeds, anti-phase inhibition is larger throughout the pool. However, as swimming speeds up, inhibition arriving in-phase with local motor activity increases, particularly in higher Rin motoneurons. Thus, in addition to systematic differences in the weight and timing of excitation related to Rin and speed, there are also speed-dependent shifts in the balance of different sources of inhibition, which is most obvious in more excitable motor pools. We conclude that synaptic drive is differentially tuned to the biophysical properties of motoneurons and argue that differences in premotor circuits exist to simplify the coordination of activity within spinal motor pools during changes in locomotor speed

    Comparing coherence measures for X states: Can quantum states be ordered based on quantum coherence?

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    Quantum coherence is an essential resource for quantum information processing and various quantitative measures of it have been introduced. However, the interconnections between these measures are not yet understood properly. Here, using a large set of randomly prepared XX states and analytically obtained expressions of various measures of coherence (e.g., relative entropy of coherence, l1l1 norm of coherence, coherence via skew information, and first-order coherence), it is established that these measures of quantum coherence cannot be used to perform ordering of a set of quantum states based on the amount of coherence present in a state. Further, it is shown that for a given value of quantum coherence measured by the relative entropy of coherence, maximally nonlocal mixed states of XX type (which are characterized by maximal violation of the CHSH inequality) have maximum quantum coherence as measured by l1l1 norm of coherence. In addition, the amount of coherence measured by l1l1 norm of coherence for a Werner state is found to be always less than that for a maximally nonlocal mixed state even when they possess an equal amount of coherence measured by the relative entropy of coherence. These resource theory based measures of coherence are not observed to show any relation with the first-order coherence, while its maximum (hidden coherence) is found to be more connected to concurrence both being basis independent quantities. These observations could be of use in obtaining a deeper understanding of the interconnections between various measures of quantum coherence.Comment: Interconnections between various measures of quantum coherence is investigated using XX state

    Horizontal gene transfer of epigenetic machinery and evolution of parasitism in the malaria parasite Plasmodium falciparum and other apicomplexans

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    Background The acquisition of complex transcriptional regulatory abilities and epigenetic machinery facilitated the transition of the ancestor of apicomplexans from a free-living organism to an obligate parasite. The ability to control sophisticated gene expression patterns enabled these ancient organisms to evolve several differentiated forms, invade multiple hosts and evade host immunity. How these abilities were acquired remains an outstanding question in protistan biology. Results In this work, we study SET domain bearing genes that are implicated in mediating immune evasion, invasion and cytoadhesion pathways of modern apicomplexans, including malaria parasites. We provide the first conclusive evidence of a horizontal gene transfer of a Histone H4 Lysine 20 (H4K20) modifier, Set8, from an animal host to the ancestor of apicomplexans. Set8 is known to contribute to the coordinated expression of genes involved in immune evasion in modern apicomplexans. We also show the likely transfer of a H3K36 methyltransferase (Ashr3 from plants), possibly derived from algal endosymbionts. These transfers appear to date to the transition from free-living organisms to parasitism and coincide with the proposed horizontal acquisition of cytoadhesion domains, the O-glycosyltransferase that modifies these domains, and the primary family of transcription factors found in apicomplexan parasites. Notably, phylogenetic support for these conclusions is robust and the genes clearly are dissimilar to SET sequences found in the closely related parasite Perkinsus marinus, and in ciliates, the nearest free-living organisms with complete genome sequences available. Conclusions Animal and plant sources of epigenetic machinery provide new insights into the evolution of parasitism in apicomplexans. Along with the horizontal transfer of cytoadhesive domains, O-linked glycosylation and key transcription factors, the acquisition of SET domain methyltransferases marks a key transitional event in the evolution to parasitism in this important protozoan lineage

    Enabling access to new WHO essential medicines: the case for nicotine replacement therapies

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    Nicotine replacement therapies (NRT) are powerful tools for the successful treatment of nicotine addiction and tobacco use. The medicines are clinically effective, supported by the Framework Convention on Tobacco Control, and are now World Health Organization-approved essential medicines. Enabling global access to NRT remains a challenge given ongoing confusion and misperceptions about their efficacy, cost-effectiveness, and availability with respect to other tobacco control and public health opportunities. In this commentary, we review existing evidence and guidelines to make the case for global access to NRT highlighting the smoker's right to access treatment to sensibly address nicotine addiction

    A Student-Led Campaign to Help Tackle Neglected Tropical Diseases

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    The authors propose that innovative student-led campaigns to address neglected diseases can and do make a practical difference

    Cytomorphometric Analysis of Oral Mucosa in Diabetic Patients in Bhopal Region an In-Situ Study

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    Background: Diabetes is a common endocrine metabolic disorder and prevalence is increasing worldwide. In condition like diabetes, premalignant lesions and iron deficiency anemia; oral exfoliative cytology may be more appropriate as the invasive techniques lose viability. Aim: The study was conducted to analyze the cytomorphometric changes in exfoliated cells of oral mucosa as an adjunct to diagnosis of diabetes. Method: Samples were collected from buccal mucosa and divided into 2 groups; 100 diabetic patients (study) and 100 healthy individuals (control). The smears were stained with rapid Papanicolaou stain (PAP). Nuclear area (NA), cytoplasmic area (CA) and cytoplasmic to nuclear ratio (CNR) were evaluated in 50 cells in each smear using Image analysis software (Magnus pro™) and research microscope (Lawrance & Mayo™). Results: Mean NA was significantly higher (p < 0.001) in study group whereas mean CA didn’t exhibit any statistically significant difference (p > 0.001). The mean CNR was significantly lower in study group (p < 0.001). Conclusion: Clinical observations and results suggested morphologic and functional alterations in oral epithelial cells in diabetic patients; detectable by microscopic and cytomorphometric analysis using exfoliative cytology and can be used in diagnosis. &nbsp

    On Essentiality and the World Health Organization's Model List of Essential Medicines

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    BackgroundIn 1977 the World Health Organization created its first Model List of Essential Medicines—a list designed to aid countries in determining which medicines to prioritize on their National Essential Medicines Lists. In classifying drugs as “essential,” the World Health Organization has historically stressed drugs' ability to meet priority health needs of populations and cost.ObjectivesIn this paper we trace the fluctuations in the application of cost and priority status of disease as criteria for essential medicines throughout the reports published by the WHO Expert Committee on Selection and Use of Essential Medicines since 1977.MethodsWe analyzed essential medicines lists published on the World Health Organization website since 1977 for trends in criteria concerning cost and priority status of disease. Where, available, analyzed the World Health Organization Expert Committee analysis rationalizing why certain medicines were or were not added and were or were not removed.ResultsThe application of the criteria of cost and priority status of essential medicines has fluctuated dramatically over the years.ConclusionsThe definition of essential medicines has shifted and now necessitates a new consensus on normative definitions and criteria. A more standardized and transparent set of procedures for choosing essential medicines is required

    Evaluation of Minimum Required Safe Distance between Two Consecutive Dental Chairs for Optimal Asepsis

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    Cross infection and self-protection, these two words are like a lurid to the health care professionals. A balance has to be maintained among those two words if not, it’s after affects areunpredictable. It is believed that even after following the code of practice, some elements such as the aerosols that are evolved during the use of high speed rotary instruments such as airotor and scaler are difficult to handle. Aerosols containing microbes from oral cavity of the patient are a risky source of infection. The best way to fight against these aerosols is to keep a distance from them. But it is not known how far these airborne microorganisms spread under various clinical environments. This article emphasizes the safe distance that has to bemaintained around each dental chair to prevent cross contamination

    Promotion of access to essential medicines for Non-Communicable Diseases: Practical implications of the UN Political Declaration

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    Access to medicines and vaccines to prevent and treat non-communicable diseases (NCDs) is unacceptably low worldwide. In the 2011 UN political declaration on the prevention and control of NCDs, heads of government made several commitments related to access to essential medicines, technologies, and vaccines for such diseases. 30 years of experience with policies for essential medicines and 10 years of scaling up of HIV treatment have provided the knowledge needed to address barriers to long-term effective treatment and prevention of NCDs. More medicines can be acquired within existing budgets with efficient selection, procurement, and use of generic medicines. Furthermore, low-income and middle-income countries need to increase mobilisation of domestic resources to cater for the many patients with NCDs who do not have access to treatment. Existing initiatives for HIV treatment offer useful lessons that can enhance access to pharmaceutical management of NCDs and improve adherence to long-term treatment of chronic illness; policy makers should also address unacceptable inequities in access to controlled opioid analgesics. In addition to off-patent medicines, governments can promote access to new and future on-patent medicinal products through coherent and equitable health and trade policies, particularly those for intellectual property. Frequent conflicts of interest need to be identified and managed, and indicators and targets for access to NCD medicines should be used to monitor progress. Only with these approaches can a difference be made to the lives of hundreds of millions of current and future patients with NCDs
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