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1.
S Afr J Surg ; 61(1): 7-13, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37052282

RESUMO

BACKGROUND: Since 2011, South African specialist registration requires a research component in the form of a Master of Medicine (MMed) degree. The aim of the study was to assess opinion regarding research and the progression and obstacles toward the completion of the research component of the MMed amongst South African surgical registrars. METHODS: One hundred and sixty-eight (24%) from 708 nationally registered surgical registrars participated. The participants completed an electronic survey that focused on research progression timeline, registrar research perspectives, factors affecting research success and obstacles, and interest in future research. RESULTS: There was an expected progression of research with increasing seniority. Forty-two (25%) started their research 6-12 months into their training time. One hundred and ten (66%) were confident their research would be completed timeously. Obstacles to timeous completion included clinical responsibilities with lack of protected research time in 130 (75%) and lack of funding in 46 (28%). From the registrars' perspective, their confidence to complete their research timeously was increased when they had attended a structured research course and had prior research experience. CONCLUSION: Completion of the MMed research component was considered to be hampered by a lack of dedicated time and funding and aided by prior research experience and a structured research training course.


Assuntos
Inquéritos e Questionários , Humanos , África do Sul
2.
Earth Space Sci ; 9(5): e2021EA002157, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35846575

RESUMO

GeoHealth research both characterizes and predicts problems at the nexus of earth and human systems like climate change, pollution, and natural hazards. While GeoHealth excels in the area of integrated science, there is a need to improve coordinated and networked efforts to produce open science to enable environmental justice. There is a need to resource and empower frontline populations that are disproportionately marginalized by environmental injustice (i.e., the unequal protection from environmental harms and lack of access and meaningful engagement in decision making for a healthy environment; EPA, 2022, https://www.epa.gov/environmentaljustice). GeoHealth practice has the opportunity to advance environmental justice or the "fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income" with respect to how research and collaboration of GeoHealth professionals supports the "development, implementation, and enforcement of environmental laws, regulations, and policies" that produce equal protection from environmental and health hazards and access to the decision making for a health environment (EPA, 2022, https://www.epa.gov/environmentaljustice). Here we highlight barriers and opportunities to apply an equity-centered ICON framework to the field of GeoHealth to advance environmental justice and health equity.

3.
Earth Space Sci ; 9(3): e2021EA002119, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35865637

RESUMO

This article is composed of three independent commentaries about the state of Integrated, Coordinated, Open, Networked (ICON) principles in the American Geophysical Union Biogeosciences section, and discussion on the opportunities and challenges of adopting them. Each commentary focuses on a different topic: (a) Global collaboration, technology transfer, and application (Section 2), (b) Community engagement, community science, education, and stakeholder involvement (Section 3), and (c) Field, experimental, remote sensing, and real-time data research and application (Section 4). We discuss needs and strategies for implementing ICON and outline short- and long-term goals. The inclusion of global data and international community engagement are key to tackling grand challenges in biogeosciences. Although recent technological advances and growing open-access information across the world have enabled global collaborations to some extent, several barriers, ranging from technical to organizational to cultural, have remained in advancing interoperability and tangible scientific progress in biogeosciences. Overcoming these hurdles is necessary to address pressing large-scale research questions and applications in the biogeosciences, where ICON principles are essential. Here, we list several opportunities for ICON, including coordinated experimentation and field observations across global sites, that are ripe for implementation in biogeosciences as a means to scientific advancements and social progress.

4.
Science ; 372(6546): 1081-1085, 2021 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-34083487

RESUMO

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera-electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

5.
Int Q Community Health Educ ; 41(2): 119-123, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32252586

RESUMO

Researchers have identified cancer, diabetes mellitus, cardiovascular, and respiratory diseases as being the principal pathologies of increased aged standardized death rates (ASDRs) among noncommunicable diseases (NCDs). The objective of this study was to compare the change in the ASDR of these principal NCDs between the years 2010 and 2016 in Botswana, Mozambique, Namibia, South Africa, and Zimbabwe. ASDR data were collected from the 2016 Global Health Estimate. Among the selected Southern African countries for both 2010 and 2016, the order of prevalence of NCDs linked to increased ASDR was cardiovascular diseases (both cardiac and stroke), cancer, diabetes mellitus, and chronic respiratory diseases. The percentage of the total number of NCDs linked to increased ASDR in relation to total deaths increased from 43.8% (in 2010) to 51.0% (in 2016) from (p < .0001). The percentage of principal NCDs in relation to total ASDR increased from 33.0% (in 2010) to 38.2% (in 2016; p < .0001).


Assuntos
Doenças Cardiovasculares , Diabetes Mellitus , Doenças não Transmissíveis , Idoso , Doenças Cardiovasculares/epidemiologia , Diabetes Mellitus/epidemiologia , Saúde Global , Humanos , Doenças não Transmissíveis/epidemiologia , África do Sul
6.
Nature ; 575(7783): 464-467, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31748724

RESUMO

Gamma-ray bursts (GRBs) are brief flashes of γ-rays and are considered to be the most energetic explosive phenomena in the Universe1. The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow-produced by the interaction between the ejected matter and the circumburst medium-slows down, and a gradual decrease in brightness is observed2. GRBs typically emit most of their energy via γ-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments3. However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elusive4. Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow-ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and γ-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies.

7.
Phys Rev Lett ; 120(20): 201101, 2018 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-29864326

RESUMO

Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy γ rays. The central region of the Milky Way halo is one of the most promising targets given its large amount of DM and proximity to Earth. We report on a search for a monoenergetic spectral line from self-annihilations of DM particles in the energy range from 300 GeV to 70 TeV using a two-dimensional maximum likelihood method taking advantage of both the spectral and spatial features of the signal versus background. The analysis makes use of Galactic center observations accumulated over ten years (2004-2014) with the H.E.S.S. array of ground-based Cherenkov telescopes. No significant γ-ray excess above the background is found. We derive upper limits on the annihilation cross section ⟨σv⟩ for monoenergetic DM lines at the level of 4×10^{-28} cm^{3} s^{-1} at 1 TeV, assuming an Einasto DM profile for the Milky Way halo. For a DM mass of 1 TeV, they improve over the previous ones by a factor of 6. The present constraints are the strongest obtained so far for DM particles in the mass range 300 GeV-70 TeV. Ground-based γ-ray observations have reached sufficient sensitivity to explore relevant velocity-averaged cross sections for DM annihilation into two γ-ray photons at the level expected from the thermal relic density for TeV DM particles.

8.
Phys Rev Lett ; 117(15): 151302, 2016 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-27768338

RESUMO

A search for dark matter linelike signals iss performed in the vicinity of the Galactic Center by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis iss developed to improve the sensitivity to linelike signals. The upgraded analysis along with newer data extend the energy coverage of the previous measurement down to 100 GeV. The 18 h of data collected with the H.E.S.S. array allow one to rule out at 95% C.L. the presence of a 130 GeV line (at l=-1.5°, b=0° and for a dark matter profile centered at this location) previously reported in Fermi-LAT data. This new analysis overlaps significantly in energy with previous Fermi-LAT and H.E.S.S. RESULTS: No significant excess associated with dark matter annihilations was found in the energy range of 100 GeV to 2 TeV and upper limits on the gamma-ray flux and the velocity weighted annihilation cross section are derived adopting an Einasto dark matter halo profile. Expected limits for present and future large statistics H.E.S.S. observations are also given.

9.
Phys Rev Lett ; 117(11): 111301, 2016 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-27661677

RESUMO

The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using γ-ray observations towards the inner 300 pc of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic Center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant γ-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section ⟨σv⟩. These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach ⟨σv⟩ values of 6×10^{-26} cm^{3} s^{-1} in the W^{+}W^{-} channel for a DM particle mass of 1.5 TeV, and 2×10^{-26} cm^{3} s^{-1} in the τ^{+}τ^{-} channel for a 1 TeV mass. For the first time, ground-based γ-ray observations have reached sufficient sensitivity to probe ⟨σv⟩ values expected from the thermal relic density for TeV DM particles.

10.
Astrophys J ; 832(No 2)2016.
Artigo em Inglês | MEDLINE | ID: mdl-29681648

RESUMO

We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole B-fields (the latter is characterized by a parameter ε), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. The offset-PC dipole B-field mimics deviations from the static dipole (which corresponds to ε = 0). In addition to constant-emissivity geometric models, we also considered a slot gap (SG) E-field associated with the offset-PC dipole B-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low E-field. Therefore, particles do not always attain the radiation-reaction limit. Our overall optimal light curve fit is for the retarded vacuum dipole field and OG model, at an inclination angle [Formula: see text] and observer angle [Formula: see text]. For this B-field, the TPC model is statistically disfavored compared to the OG model. For the static dipole field, neither model is significantly preferred. We found that smaller values of ε are favored for the offset-PC dipole field when assuming constant emissivity, and larger ε values favored for variable emissivity, but not significantly so. When multiplying the SG E-field by a factor of 100, we found improved light curve fits, with α and ζ being closer to best fits from independent studies, as well as curvature radiation reaction at lower altitudes.

11.
Accid Anal Prev ; 86: 99-107, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26536073

RESUMO

Research into anxiety and driving has indicated that those higher in anxiety are potentially more dangerous on the roads. However, simulator findings suggest that conclusions are mixed at best. It is possible that anxiety is becoming confused with fear, which has a focus on more clearly defined sources of threat from the environment, as opposed to the internal, thought-related process associated with anxiety. This research aimed to measure feelings of fear, as well as physiological and attentional reactions to increasing levels of accident risk. Trait anxiety was also measured to see if it interacted with levels of risk or its associated reactions. Participants watched videos of driving scenarios with varying levels of accident risk and had to rate how much fear they would feel if they were the driver of the car, whilst skin conductance, heart rate, and eye movements were recorded. Analysis of the data suggested that perceptions of fear increased with increasing levels of accident risk, and skin conductance reflected this pattern. Eye movements, when considered alongside reaction times, indicated different patterns of performance according to different dangerous situations. These effects were independent of trait anxiety, which was only associated with higher rates of disliking driving and use of maladaptive coping mechanisms on questionnaires. It is concluded that these results could provide useful evidence in support for training-based programmes; it may also be beneficial to study trait anxiety within a more immersive driving environment and on a larger scale.


Assuntos
Ansiedade/psicologia , Nível de Alerta , Condução de Veículo/psicologia , Diagnóstico por Computador , Medo , Testes Neuropsicológicos/estatística & dados numéricos , Meio Social , Acidentes de Trânsito/psicologia , Adolescente , Adulto , Ansiedade/diagnóstico , Simulação por Computador , Comportamento Perigoso , Feminino , Frequência Cardíaca , Humanos , Masculino , Psicometria/estatística & dados numéricos , Tempo de Reação , Reprodutibilidade dos Testes , Estatística como Assunto , Adulto Jovem
12.
Int J Lab Hematol ; 37(1): 112-9, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24806286

RESUMO

INTRODUCTION: Early and accurate identification of acute coronary syndrome (ACS) vs. noncardiac chest pain in patients presenting to the emergency department (ED) is problematic and new diagnostic markers are needed. Previous studies reported that elevated mean platelet volume (MPV) is associated with ACS and predictive of cardiovascular risk. MPV is closely related to the immature platelet fraction (IPF), and recent studies have suggested that IPF may be a more sensitive marker of ACS than MPV. The objective of the present study was to determine whether the measurement of IPF assists in the diagnosis of ACS in patients presenting to the ED with chest pain. METHODS: In this single-center, prospective, cross-sectional study, adult patients presenting to the ED with chest pain and/or suspected ACS were considered for enrollment. Blood samples from 236 ACS-negative and 44 ACS-positive patients were analyzed in a Sysmex XE-2100 for platelet count, MPV, IPF, and the absolute count of immature platelets (IPC). RESULTS: Total platelet counts, MPV, IPF, and IPC were not statistically different between ACS-negative and ACS-positive patients. The IPF was 4.6 ± 2.7% and 5.0 ± 2.8% (mean ± SD, P = 0.24), and the IPC was 10.0 ± 4.6 and 11.5 ± 7.5 × 10(3) /µL (P = 0.27) for ACS-negative and ACS-positive patients, respectively. CONCLUSION: In 280 patients presenting to the ED with chest pain and/or suspected ACS, no differences in IPF, IPC or MPV were observed in ACS-negative vs. ACS-positive patients, suggesting that these parameters do not assist in the diagnosis of ACS.


Assuntos
Síndrome Coronariana Aguda/sangue , Síndrome Coronariana Aguda/diagnóstico , Plaquetas/citologia , Dor no Peito/diagnóstico , Dor no Peito/etiologia , Serviço Hospitalar de Emergência , Contagem de Plaquetas , Idoso , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fatores de Risco
13.
Artigo em Inglês | MEDLINE | ID: mdl-25535577

RESUMO

UNLABELLED: Tuberculosis (TB) is an important cause of mortality and morbidity across the world. In 2-5% of all cases of systemic TB, the C is affected, with lesions reported in the meninges, cortex and ventricles. Intrasellar tuberculomas, however, are extremely rare. We report the interesting case of a young female patient who presented with secondary hypothyroidism and hyperprolactinaemia. She was treated successfully for pituitary TB. We also highlight and discuss some interesting (and hitherto unreported) endocrine issues. Radiological and histological features and treatment of pituitary TB are discussed using this case as an example. LEARNING POINTS: Intrasellar TB continues to be a rare presentation, but incidence and prevalence are expected to grow with increasing numbers of multidrug-resistant TB and shrinking geographical boundaries across the world.Pituitary TB can present with features of a typical adenoma, but has certain radiological and histological features that help to differentiate from an adenoma.Patients can present with a variety of endocrine abnormalities at different times.The presence of an intrasellar mass in individuals at a high risk of developing TB, or with a previous history of systemic TB, should prompt the diagnosis of pituitary TB. In such individuals, it may be worth considering a trial of anti-tuberculous therapy, before considering surgery.

14.
J Thromb Haemost ; 10(12): 2573-80, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23083103

RESUMO

BACKGROUND: Diadenosine 5',5'''-P(1),P(4)-tetraphosphate (Ap(4)A), a natural compound stored in platelet dense granules, inhibits ADP-induced platelet aggregation. Ap(4)A inhibits the platelet ADP receptors P2Y(1) and P2Y(12), is a partial agonist of P2Y(12), and is a full agonist of the platelet ATP-gated ion channel P2X1. Modification of the Ap(4)A tetraphosphate backbone enhances inhibition of ADP-induced platelet aggregation. However, the effects of these Ap(4)A analogs on human platelet P2Y(1), P2Y(12) and P2X1 are unclear. OBJECTIVE: To determine the agonist and antagonist activities of diadenosine tetraphosphate analogs towards P2Y(1), P2Y(12), and P2X1. METHODS: We synthesized the following Ap(4)A analogs: P(1),P(4)-dithiotetraphosphate; P(2),P(3)-chloromethylenetetraphosphate; P(1)-thio-P(2),P(3)-chloromethylenetetraphosphate; and P(1),P(4)-dithio-P(2),P(3)-chloromethylenetetraphosphate. We then measured the effects of these analogs on: (i) ADP-induced platelet aggregation; (ii) P2Y(1)-mediated changes in cytosolic Ca(2+); (iii) P2Y(12)-mediated changes in vasodilator-stimulated phosphoprotein phosphorylation; and (iv) P2X1-mediated entry of extracellular Ca(2+). RESULTS: Ap(4)A analogs with modifications in the phosphate backbone inhibited both P2Y(1) and P2Y(12), and showed no agonist activity towards these receptors. The dithio modification increased inhibition of P2Y(1), P2Y(12), and platelet aggregation, whereas the chloromethylene modification increased inhibition of P2Y(12) and platelet aggregation, but decreased P2Y(1) inhibition. Combining the dithio and chloromethylene modifications increased P2Y(1) and P2Y(12) inhibition. As compared with Ap(4)A, each modification decreased agonist activity towards P2X1, and the dual modification completely eliminated P2X1 agonist activity. CONCLUSIONS: As compared with Ap(4)A, tetraphosphate backbone analogs of Ap(4)A have diminished activity towards P2X1 but inhibit both P2Y(1) and P2Y(12) and, with greater potency, inhibit ADP-induced platelet aggregation. Thus, diadenosine tetraphosphate analogs with dual receptor selectivity may have potential as antiplatelet drugs.


Assuntos
Difosfato de Adenosina/farmacologia , Fosfatos de Dinucleosídeos/farmacologia , Ativação Plaquetária/efeitos dos fármacos , Receptores Purinérgicos P2Y12/metabolismo , Receptores Purinérgicos P2Y1/metabolismo , Humanos , Fosforilação
15.
J Clin Microbiol ; 50(11): 3712-6, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22972826

RESUMO

Molecular diagnostics for Mycobacterium tuberculosis have recently been endorsed by the World Health Organization. The Xpert MTB/RIF assay was endorsed for use on patient material, regardless of smear gradation, while the GenoType MTBDRplus (version 1) has been limited for use on smear-positive patient material. In this study, we evaluated the diagnostic performance of the Xpert MTB/RIF and GenoType MTBDRplus (version 2) assays on smear-positive and smear-negative patient specimens submitted to a high-throughput diagnostic laboratory. A total of 282 consecutive specimens were subjected to the two new molecular assays, and their performance characteristics were assessed relative to the routine diagnostic standard. Both assays showed similar diagnostic performance characteristics. The sensitivities of the GenoType MTBDRplus (v2.0) and Xpert MTB/RIF assays for the detection of culture-positive M. tuberculosis were 73.1% and 71.2%, respectively, while the specificities of both assays were 100%. Both assays were able to diagnose the presence of M. tuberculosis in 57 to 58% of smear-negative cases, suggesting that the performance characteristics were dependent on bacillary load. The detection of M. tuberculosis in culture-negative specimens confirmed that molecular assays should not be used for treatment monitoring. The sensitivity and specificity for rifampin resistance detection were 100% in both assays; however, the GenoType MTBDRplus (v2.0) assay provided additional information on isoniazid susceptibility. The GenoType MTBDRplus (v2.0) assay will complement the Xpert MTB/RIF screening assay by validating rifampin susceptibility and providing information on isoniazid susceptibility. In addition, the GenoType MTBDRplus (v2.0) assay will provide pharmacogenetic information that may be critical in guiding appropriate treatment.


Assuntos
Técnicas Bacteriológicas/métodos , Técnicas de Diagnóstico Molecular/métodos , Mycobacterium tuberculosis/isolamento & purificação , Tuberculose/diagnóstico , Tuberculose/microbiologia , Farmacorresistência Bacteriana , Genótipo , Humanos , Mycobacterium tuberculosis/genética , Sensibilidade e Especificidade
16.
J Thromb Haemost ; 9(11): 2302-10, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21920014

RESUMO

BACKGROUND: Severe thrombocytopenia is a major risk factor for hemorrhage, but platelet function and bleeding risk at low platelet counts are poorly understood, because of the limitations of platelet function testing at very low platelet counts. OBJECTIVES: To examine and compare platelet function in severely thrombocytopenic patients with acute myeloid leukemia (AML) or myelodysplasia (MDS) with that in patients with immune thrombocytopenia (ITP). METHODS: Whole blood flow cytometric measurement of platelet activation and platelet reactivity to agonists was correlated with the immature platelet fraction (IPF) and bleeding symptoms. RESULTS: Patients with AML/MDS had smaller platelets, lower IPF and substantially lower platelet surface expression of activated glycoprotein (GP)IIb-IIIa and GPIb, both with and without addition of ex vivo ADP or thrombin receptor-activating peptide, than patients with ITP. In both ITP and AML/MDS patients, increased platelet surface GPIb on circulating platelets and expression of activated GPIIb-IIIa and GPIb on ex vivo activated platelets correlated with a higher IPF. Whereas platelet reactivity was higher for AML/MDS patients with bleeding than for those with no bleeding, platelet reactivity was lower for ITP patients with bleeding than for those with no bleeding. CONCLUSIONS: AML/MDS patients have lower in vivo platelet activation and ex vivo platelet reactivity than patients with ITP. The proportion of newly produced platelets correlates with the expression of platelet surface markers of activation. These differences might contribute to differences in bleeding tendency between AML/MDS and ITP patients. This study is the first to define differences in platelet function between AML/MDS patients and ITP patients with equivalent degrees of thrombocytopenia.


Assuntos
Plaquetas/fisiologia , Leucemia Mieloide Aguda/sangue , Síndromes Mielodisplásicas/sangue , Púrpura Trombocitopênica Idiopática/sangue , Idoso , Plaquetas/patologia , Forma Celular , Feminino , Citometria de Fluxo , Hemorragia , Humanos , Masculino , Pessoa de Meia-Idade , Ativação Plaquetária , Glicoproteínas da Membrana de Plaquetas/análise
17.
Thromb Res ; 125(2): 159-65, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19945153

RESUMO

INTRODUCTION: Diadenosine 5',5'''-P(1),P(4)- tetraphosphate (Ap(4)A) is stored in platelet dense granules, but its effects on platelet function are not well understood. METHODS AND RESULTS: We examined the effects of Ap(4)A on platelet purinergic receptors P2Y(1), P2Y(12) and P2X(1). Flow cytometry was used to measure the effects of Ap(4)A in the presence or absence of ADP on: a) P2Y(12)-mediated decrease in intraplatelet phosphorylated vasodilator stimulated phosphoprotein (VASP), b) P2Y(1)-mediated increase in platelet cytosolic Ca(2+), and c) P2X(1)-mediated intraplatelet entry of extracellular Ca(2+). ADP-stimulated platelet shape change (P2Y(1)-mediated) and aggregation (P2Y(1)- and P2Y(12)-mediated) were measured optically. Ap(4)A inhibited 3 microM ADP-induced: a) platelet aggregation (IC(50) 9.8+/-2.8 microM), b) P2Y(1)-mediated shape change, c) P2Y(1)-mediated increase in platelet cytosolic Ca(2+) (IC(50) 40.8+/-12.3 microM), and d) P2Y(12)-mediated decrease in VASP phosphorylation (IC(50)>250 microM). In the absence of added ADP, Ap(4)A had agonist effects on platelet P2X(1) and P2Y(12), but not P2Y(1), receptors. CONCLUSION: Ap(4)A, a constituent of platelet dense granules, is a) an antagonist of platelet P2Y(1) and P2Y(12) receptors, where it inhibits the effects of ADP, and b) an agonist of platelet P2X(1) and P2Y(12) receptors.


Assuntos
Grânulos Citoplasmáticos/metabolismo , Fosfatos de Dinucleosídeos/metabolismo , Agonistas do Receptor Purinérgico P2 , Antagonistas do Receptor Purinérgico P2 , Plaquetas/metabolismo , Fosfatos de Dinucleosídeos/farmacologia , Relação Dose-Resposta a Droga , Humanos , Receptores Purinérgicos P2X , Receptores Purinérgicos P2Y1 , Receptores Purinérgicos P2Y12
18.
J Thromb Haemost ; 8(2): 331-40, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19922435

RESUMO

BACKGROUND: Release of serotonin and activation of serotonin 5HT2A receptors on platelet surfaces is a potent augmentative stimulus for platelet aggregation. However, earlier-generation serotonin receptor antagonists were not successfully exploited as antiplatelet agents, possibly owing to their lack of specificity for the 5HT2A receptor subtype. OBJECTIVE: To assess whether targeted inhibition of the serotonin 5HT2A receptor attenuates recurrent thrombosis and improves coronary patency in an in vivo canine model mimicking unstable angina. METHODS: In protocol 1, anesthetized dogs were pretreated with a novel, selective inverse agonist of the 5HT2A receptor (APD791) or saline. Recurrent coronary thrombosis was then initiated by coronary artery injury+stenosis, and coronary patency was monitored for 3 h. Protocol 2 was similar, except that: (i) treatment with APD791 or saline was begun 1 h after the onset of recurrent thrombosis; (ii) template bleeding time was measured; and (iii) blood samples were obtained for in vitro flow cytometric assessment of platelet responsiveness to serotonin. RESULTS: APD791 attenuated recurrent thrombosis, irrespective of the time of treatment: in both protocols, flow-time area (index of coronary patency; normalized to baseline coronary flow) averaged 58-59% (P<0.01) following administration of APD791 vs. 21-28% in saline controls. Moreover, the in vivo antithrombotic effect of APD791 was not accompanied by increased bleeding, but was associated with significant and selective inhibition of serotonin-mediated platelet activation. CONCLUSION: 5HT2A receptor inhibition with APD791, even when initiated after the onset of recurrent thrombosis, improves coronary patency in the in vivo canine model.


Assuntos
Benzamidas/farmacologia , Plaquetas/efeitos dos fármacos , Trombose Coronária/tratamento farmacológico , Fibrinolíticos/farmacologia , Morfolinas/farmacologia , Inibidores da Agregação Plaquetária/farmacologia , Pirazóis/farmacologia , Antagonistas do Receptor 5-HT2 de Serotonina , Antagonistas da Serotonina/farmacologia , Grau de Desobstrução Vascular/efeitos dos fármacos , Animais , Benzamidas/sangue , Benzamidas/toxicidade , Plaquetas/metabolismo , Circulação Coronária/efeitos dos fármacos , Trombose Coronária/sangue , Trombose Coronária/patologia , Trombose Coronária/fisiopatologia , Modelos Animais de Doenças , Cães , Agonismo Inverso de Drogas , Fibrinolíticos/sangue , Fibrinolíticos/toxicidade , Hemodinâmica/efeitos dos fármacos , Hemorragia/induzido quimicamente , Morfolinas/sangue , Morfolinas/toxicidade , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/sangue , Inibidores da Agregação Plaquetária/toxicidade , Pirazóis/sangue , Pirazóis/toxicidade , Receptor 5-HT2A de Serotonina/sangue , Recidiva , Antagonistas da Serotonina/sangue , Antagonistas da Serotonina/toxicidade , Fatores de Tempo
19.
Diabet Med ; 26(5): 540-7, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19646195

RESUMO

AIMS: To determine whether continuous glucose information provided through use of either the GlucoWatch G2 Biographer or the MiniMed continuous glucose monitoring system (CGMS) results in improved glycated haemoglobin (HbA(1c)) for insulin-treated adults with diabetes mellitus, relative to an attention control and standard care group. METHODS: Four hundred and four adults taking at least two daily insulin injections and with two consecutive HbA(1c) values > or = 7.5% were recruited to this randomized controlled trial (RCT). All were trained at baseline to use the same monitor for traditional capillary glucose testing throughout the 18-month study. The CGMS group were asked to wear the device three times during the first 3 months of the trial and on another three occasions thereafter. The GlucoWatch group wore the device a minimum of four times per month and a maximum of four times per week during the first 3 months and as desired for the remainder of the trial. Trained diabetes research nurses used downloaded data to guide therapy adjustments. Proportional reduction in HbA(1c) from baseline to 18 months was the primary outcome measure. RESULTS: Neither an intention-to-treat nor per-protocol analysis showed improvement in HbA(1c) in the device groups compared with standard care. For the intention-to-treat analysis, when the standard care group was compared with each of the other groups, this equated to differences in mean relative HbA(1c) reduction (95% confidence interval) from baseline to 18 months of 3.5% (-1.3 to 8.3; GlucoWatch), 0.7% (-4.1 to 5.5; CGMS), and -0.1% (-4.6 to 4.3; attention control). CONCLUSIONS: The additional information provided by these devices did not result in improvements in HbA(1c) in this population.


Assuntos
Automonitorização da Glicemia/instrumentação , Diabetes Mellitus Tipo 1/sangue , Hemoglobinas Glicadas/análise , Monitorização Fisiológica/instrumentação , Adulto , Idoso , Glicemia/metabolismo , Automonitorização da Glicemia/psicologia , Diabetes Mellitus Tipo 1/diagnóstico , Feminino , Humanos , Insulina/administração & dosagem , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Cooperação do Paciente
20.
Health Technol Assess ; 13(28): iii-iv, ix-xi, 1-194, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19476724

RESUMO

OBJECTIVES: To evaluate whether the additional information provided by minimally invasive glucose monitors results in improved glycaemic control in people with poorly controlled insulin-requiring diabetes, and to assess the acceptability and health economic impact of the devices. DESIGN: A four-arm randomised controlled trial was undertaken. SETTING: Participants were recruited from secondary care diabetes clinics in four hospitals in England. PARTICIPANTS: 404 people aged over 18 years with insulin-treated diabetes mellitus (types 1 or 2) for at least 6 months who were receiving two or more injections of insulin daily were eligible. Participants had to have had two glycosylated haemoglobin (HbA1c) values > or = 7.5% in the last 15 months. INTERVENTIONS: Participants were randomised to one of four groups. Two groups received minimally invasive glucose monitoring devices [GlucoWatch Biographer or MiniMed Continuous Glucose Monitoring System (CGMS)]. These groups were compared with an attention control group (standard treatment with nurse feedback sessions at the same frequency as those in the device groups) and a standard control group (reflecting common practice in the clinical management of diabetes in the UK). MAIN OUTCOME MEASURES: Change in HbA1c from baseline to 3, 6, 12 and 18 months was the primary indicator of short- to long-term efficacy in this study. Perceived acceptability of the devices was assessed by use and a self-report questionnaire. A health economic analysis was also performed. RESULTS: At 18 months all groups demonstrated a decline in HbA1c levels from baseline. Mean percentage changes in HbA1c were -1.4 for the GlucoWatch group, -4.2 for the CGMS group, -5.1 for the attention control group and -4.9 for the standard care control group. At 18 months the relative percentage reduction in HbA1c in each of the intervention arms was less than that in the standard care control group. In the intention to treat analysis no significant differences were found between any of the groups at any of the assessment times. There was no evidence that the additional information provided by the devices resulted in any change in the number or nature of treatment recommendations offered by the nurses. The health economics analysis indicated no advantage in the groups who received the devices; a lower cost and higher benefit were found for the attention control arm. Assessment of device use and acceptability indicated a decline in use of both devices, which was most marked in the GlucoWatch group by 18 months (20% still using GlucoWatch versus 57% still using the CGMS). The GlucoWatch group reported more side effects, greater interference with daily activities and more difficulty in using the device than the CGMS group. CONCLUSIONS: Continuous glucose monitors do not lead to improved clinical outcomes and are not cost-effective for improving HbA1c in unselected individuals with poorly controlled insulin-requiring diabetes. On acceptability grounds the data suggest that the GlucoWatch will not be frequently used by individuals with diabetes because of the large number of side effects.


Assuntos
Glicemia/análise , Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Monitorização Fisiológica/instrumentação , Adulto , Idoso , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/epidemiologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/epidemiologia , Feminino , Hemoglobinas Glicadas/análise , Humanos , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Pacientes/psicologia , Avaliação da Tecnologia Biomédica , Reino Unido/epidemiologia
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