1,065 research outputs found
Use of Nitroglycerin in the Active Phase of Tilt Testing: Is There a Difference in Elderly Patients?
Está demonstrado o papel do teste de inclinação na avaliação de doentes com sĂncope de causa nĂŁo esclarecida, sendo utilizado como a tĂ©cnica gold standard para o diagnĂłstico da sĂncope neurocardiogĂ©nica, em particular com o recurso a agentes provocativos farmacolĂłgicos de modo a melhorar a acuidade diagnĂłstica. A estimulação com nitroglicerina sub-lingual Ă©, regra geral, bem tolerada e permite aumentar a sensibilidade do teste reduzindo a sua duração. Neste sentido, tem-se verificado tambĂ©m o alargamento da sua aplicação em doentes idosos.
Objectivos: Avaliar, numa população referenciada por sĂncope de etiologia desconhecida, a utilidade do teste de inclinação com recurso a nitroglicerina sub-lingual e comparar o tipo de respostas obtidas nos doentes idosos com o dos restantes doentes. MĂ©todos: Estudámos 158 doentes submetidos a teste de inclinação com utilização de nitroglicerina como agente provocativo. Foram considerados doentes com idade <65 anos (Grupo A, n=74) e ≥65 anos (Grupo B, n=84). O teste de inclinação foi efectuado segundo o protocolo “italiano”, sob monitorização contĂnua do electrocardiograma e da tensĂŁo arterial (Task Force Monitor; CNSystems). Foram incluĂdos somente doentes assintomáticos na fase passiva do teste. O teste foi considerado positivo para resposta neurocardiogĂ©nica quando houve reprodução da sintomatologia acompanhada de bradicardia e/ou hipotensĂŁo arterial e as respostas foram definidas como cardio-inibitĂłria, vasodepressora ou mista. Uma descida gradual e paralela da tensĂŁo arterial apĂłs administração de nitroglicerina seguida de sĂncope foi considerada como resposta exagerada aos nitratos.
Resultados: Não se verificam diferenças na distribuição por sexos entre os grupos. O teste de inclinação foi positivo em 57% do Grupo A e 51% do Grupo B (p=NS), tendo ocorrido resposta exagerada aos nitratos em 11% e 16%, respectivamente (p=NS). Relativamente ao tipo de respostas neurocardiogénicas, as vasodepressoras foram mais frequentes no Grupo B (53% versus 24%; p=0,001) e as mistas tendencialmente mais frequentes no Grupo A (59% versus 40%; p=0,07), sem diferenças significativas no que se refere à resposta do tipo cardio-inibitória (17% nos Grupo A versus 7% no Grupo B; p=NS).
Conclusões: Numa população com sĂncope de etiologia nĂŁo conhecida, o teste de inclinação potenciado pela nitroglicerina: a) contribui de modo significativo para o esclarecimento diagnĂłstico com utilidade idĂŞntica em idosos e nos restantes doentes. B) associa-se a maior incidĂŞncia de resposta neurocardiogĂ©nica vasodepressora nos idosos embora com uma taxa semelhante de respostas exageradas aos nitratos
Head-Up Tilt Testing with Different Nitroglycerin Dosages: Experience in Elderly Patients with Unexplained Syncope
AIMS: Protocols using sublingual nitrates have been increasingly used to improve diagnostic accuracy of head-up tilt testing (HUT). Nevertheless, exaggerated responses to nitrates have been frequently described, particularly in elderly patients. The aim of this article is to evaluate, in an elderly population with unexplained syncope, whether the impact of sublingual nitroglycerin (NTG) used as a provocative agent is dose-dependent.
METHODS AND RESULTS: One hundred and twenty consecutive elderly patients submitted to HUT using NTG after an asymptomatic drug-free phase were studied. Patients were divided into three groups according to the NTG dosage: 500, 375 and 250 microg. The test was considered positive when there was reproduction of symptoms with bradycardia and/or arterial hypotension. A gradual decrease in the blood pressure after NTG was considered an exaggerated response to nitrates. There were no differences in the clinical characteristics of the different subgroups. A positive test was obtained in 50% of the patients in each group. The rate of exaggerated responses was identical in all groups and ranged between 15 and 17%.
CONCLUSION: In an elderly population with syncope of unknown origin submitted to HUT, the response to NTG is not dose-dependent, and no difference was found in the rate of exaggerated responses to nitrates with different NTG dosages
Tilt Test in Elderly Patients with Syncope of Unknown Etiology: Experience with Pharmacological Stimulation with Nitroglycerin
Está demonstrado o papel do teste de inclinação na avaliação de doentes com sĂncope de causa nĂŁo esclarecida. Nos idosos, a prevalĂŞncia de episĂłdios sincopais aumenta, associa-se a pior prognĂłstico e, frequentemente, implica o recurso a mĂşltiplos exames de diagnĂłstico.
Objectivos: Avaliar a utilidade do teste de inclinação com recurso a nitroglicerina sub-lingual como agente provocativo em idosos com sĂncope de etiologia desconhecida.
MĂ©todos: Foram estudados 46 doentes consecutivos com > 65 anos (56,5% do sexo feminino; 74 ± 6 anos) por sĂncope de etiologia nĂŁo esclarecida. Em 25 doentes(54%) nĂŁo havia evidĂŞncia de patologia cardĂaca, tendo os restantes cardiopatia hipertensiva (14 doentes) ou isquĂ©mica (7 doentes). O protocolo incluiu massagem do seio carotĂdeo em decĂşbito a apĂłs ortostatismo passivo. O teste de inclinação foi efectuado sob monitorização contĂnua do electrocardiograma e tensĂŁo arterial, com inclinação a 70Âş durante 20 minutos. Na ausĂŞncia de sĂncope, administrou-se 500 mcg de nitroglicerina sub-lingual com monitorização por mais 20 minutos. O teste de inclinação foi considerado positivo quando houve reprodução da sintomatologia acompanhada de bradicardia e/ou hipotensĂŁo arterial (respostas cardio-inibitĂłria, vasodepressora ou mista). Considerou-se haver hipotensĂŁo ortostática nos casos com queda da tensĂŁo arterial sistĂłlica > 20 mmHg ou da tensĂŁo arterial diastĂłlica > 10 mmHg nos 3 minutos apĂłs ortostatismo; nos doentes com sintomas associados Ă descida gradual, paralela, da tensĂŁo arterial sistĂłlica e diastĂłlica durante o teste de inclinação passivo, admitiu-se um perfil do tipo disautonĂłmico; nos doentes com descida gradual da tensĂŁo arterial apĂłs nitroglicerina, considerou-se haver resposta exagerada aos nitratos.
Resultados: Ocorreu reprodução de sintomas em 34 doentes (73,9%): 19,6% no teste de inclinação passivo (resposta neurocardiogĂ©nica vasodepressora – 3 doentes, hipersensibilidade do seio carotĂdeo – 1 doente, hipotensĂŁo ortostática – 1 doente, perfil disautonĂłmico – 4 doentes) e 54,3% apĂłs nitroglicerina (resposta neurocardiogĂ©nica vasodepressora – 12 doentes, mista – 5 doentes , cardio-inibitĂłria – 2 doentes e resposta exagerada aos nitratos – 6 doentes). A sĂncope foi neurocardiogĂ©nica em 47,8% (teste passivo – 13,6%, pĂłs-nitroglicerina – 86,4%). Em 16,2% dos doentes submetidos a nitroglicerina ocorreu resposta exagerada aos nitratos. NĂŁo se registaram complicações durante o exame.
Conclusões: O teste de inclinação em idosos com sĂncope de etiologia nĂŁo esclarecida: 1. contribui para o diagnĂłstico diferencial no estudo etiolĂłgico da sĂncope, 2. quando potenciado pela nitroglicerina associa-se a um aumento significativo do nĂşmero de respostas positivas, e permite identificar um nĂşmero considerável de doentes com resposta exagerada aos nitratos
Rabies virus in a pregnant naturally infected southern yellow bat (Lasiurus ega)
Current knowledge on bat lyssavirus infections in their native hosts is limited and little is known about the virulence, virus dissemination and transmission among free-living insectivorous bats. The present study is a brief description of rabies virus (RABV) dissemination in tissues of a naturally infected pregnant southern yellow bat (Lasiurus ega) and its fetuses, obtained by reverse-transcriptase polymerase chain reaction (RT-PCR). The RT-PCR was positive in samples from the brain, salivary gland, tongue, lungs, heart, kidneys and liver. On the other hand, the placenta, three fetuses, spleen, intestine and brown fat tissue tested negative. This research demonstrated the absence of rabies virus in the fetuses, thus, in this specific case, the transplacentary transmission was not observed
False Positive Responses to Head-Up Tilt Testing in Elderly Patients with Paroxysmal Atrial Fibrillation
The autonomic nervous system (ANS) plays a role as a modulator in the pathogenesis of paroxysmal atrial fibrillation (PAF). The clinical pattern of vagally mediated PAF has been observed mainly in young patients. Neurocardiogenic responses during orthostatic stress are related to autonomic reflexes in which the vagal influence predominates.
AIM: To evaluate the susceptibility of elderly patients with PAF to activation of vasovagal syncope mechanisms.
METHODS: We performed passive head-up tilt testing (HUT) in 34 patients (62% women, aged 72 +/- 7 years), with > or = 1 year of clinical history of PAF--19 without structural heart disease, 11 with hypertensive heart disease and 4 with coronary artery disease (who had no previous myocardial infarction, had undergone myocardial revascularization, and had no documented ischemia) (PAF group), and compared the results with those obtained in a group of 34 age-matched patients (53% women, aged 74 +/- 6 years), who underwent HUT due to recurrent syncope (Sc group). In this group, 21 had no documented heart disease and none had a clinical history of AF. There was no diabetes, congestive heart failure or syncope in the PAF group. After a supine resting period, the subjects were tilted at 70 degrees for 20 minutes while in sinus rhythm. No provocative agents were used to complement the HUT. ECG and blood pressure were continuously monitored (Task Force Monitor, CNSystems). The test was considered positive when syncope or presyncope occurred with bradycardia and/or arterial hypotension. Abnormal responses were classified as cardioinhibitory, vasodepressor or mixed.
RESULTS: HUT was positive in seven patients of the PAF group--vasodepressor response in five and mixed in two (20.5% of the total; 26.3% of those without heart disease)--and in eight patients (vasodepressor in six and mixed in two) of the Sc group (p=NS). During HUT, three patients of the PAF group had short periods of self-limited PAF (in one, after vasodepressor syncope). There were no differences in gender distribution, age or heart disease. No cardioinhibitory responses or orthostatic hypotension were observed.
CONCLUSION: In elderly patients with PAF, a significant number of false positive results during passive HUT may be expected, suggesting increased vasovagal reactions despite aging. This suggests that ANS imbalances may be observed in this population
Depth, Highness and DNR Degrees
A sequence is Bennett deep [5] if every recursive approximation of the
Kolmogorov complexity of its initial segments from above satisfies that the difference
between the approximation and the actual value of the Kolmogorov complexity of
the initial segments dominates every constant function. We study for different lower
bounds r of this difference between approximation and actual value of the initial segment
complexity, which properties the corresponding r(n)-deep sets have. We prove
that for r(n) = εn, depth coincides with highness on the Turing degrees. For smaller
choices of r, i.e., r is any recursive order function, we show that depth implies either
highness or diagonally-non-recursiveness (DNR). In particular, for left-r.e. sets, order
depth already implies highness. As a corollary, we obtain that weakly-useful sets are
either high or DNR. We prove that not all deep sets are high by constructing a low
order-deep set.
Bennett's depth is defined using prefix-free Kolmogorov complexity. We show that
if one replaces prefix-free by plain Kolmogorov complexity in Bennett's depth definition,
one obtains a notion which no longer satisfies the slow growth law (which
stipulates that no shallow set truth-table computes a deep set); however, under this
notion, random sets are not deep (at the unbounded recursive order magnitude). We
improve Bennett's result that recursive sets are shallow by proving all K-trivial sets
are shallow; our result is close to optimal.
For Bennett's depth, the magnitude of compression improvement has to be achieved
almost everywhere on the set. Bennett observed that relaxing to infinitely often is
meaningless because every recursive set is infinitely often deep. We propose an alternative
infinitely often depth notion that doesn't suffer this limitation (called i.o.
depth).We show that every hyperimmune degree contains a i.o. deep set of magnitude
εn, and construct a π01- class where every member is an i.o. deep set of magnitude
εn. We prove that every non-recursive, non-DNR hyperimmune-free set is i.o. deep
of constant magnitude, and that every nonrecursive many-one degree contains such
a set
Leishmania Parasites Drive PD-L1 Expression in Mice and Human Neutrophils With Suppressor Capacity
Neutrophils play an important role in the outcome of leishmaniasis, contributing either to exacerbating or controlling the progression of infection, a dual effect whose underlying mechanisms are not clear. We recently reported that CD4+ and CD8+ T cells, and dendritic cells of Leishmania amazonensis-infected mice present high expression of PD-1 and PD-L1, respectively. Given that the PD-1/PD-L1 interaction may promote cellular dysfunction, and that neutrophils could interact with T cells during infection, we investigated here the levels of PD-L1 in neutrophils exposed to Leishmania parasites. We found that both, promastigotes and amastigotes of L. amazonensis induced the expression of PD-L1 in the human and murine neutrophils that internalized these parasites in vitro. PD-L1-expressing neutrophils were also observed in the ear lesions and the draining lymph nodes of L. amazonensis-infected mice, assessed through cell cytometry and intravital microscopy. Moreover, expression of PD-L1 progressively increased in neutrophils from ear lesions as the disease evolved to the chronic phase. Co-culture of infected neutrophils with in vitro activated CD8+ T cells inhibits IFN-Îł production by a mechanism dependent on PD-1 and PD-L1. Importantly, we demonstrated that in vitro infection of human neutrophils by L braziliensis induced PD-L1+ expression and also PD-L1+ neutrophils were detected in the lesions of patients with cutaneous leishmaniasis. Taken together, these findings suggest that the Leishmania parasite increases the expression of PD-L1 in neutrophils with suppressor capacity, which could favor the parasite survival through impairing the immune response
Agronomic Management of Indigenous Mycorrhizas
Many of the advantages conferred to plants by arbuscular mycorrhiza (AM) are associated to the ability of AM plants to explore a greater volume of soil through the extraradical mycelium. Sieverding (1991) estimates that for each centimetre of colonized root there is an increase of 15 cm3 on the volume of soil explored, this value can increase to 200 cm3 depending on the circumstances. Due to the enhancement of the volume of soil explored and the ability of the extraradical mycelium to absorb and translocate nutrients to the plant, one of the most obvious and important advantages resulting from mycorrhization is the uptake of nutrients. Among of which the ones that have immobilized forms in soil, such as P, assume particular significance. Besides this, many other benefits are recognized for AM plants (Gupta et al, 2000): water stress alleviation (Augé, 2004; Cho et al, 2006), protection from root pathogens (Graham, 2001), tolerance to toxic heavy metals and phytoremediation (Audet and Charest, 2006; Göhre and Paszkowski, 2006), tolerance to adverse conditions such as very high or low temperature, high salinity (Sannazzaro et al, 2006), high or low pH (Yano and Takaki, 2005) or better performance during transplantation shock (Subhan et al, 1998). The extraradical hyphae also stabilize soil aggregates by both enmeshing soil particles (Miller e Jastrow, 1992) and producing a glycoprotein, golmalin, which may act as a glue-like substance to adhere soil particles together (Wright and Upadhyaya, 1998).
Despite the ubiquous distribution of mycorrhizal fungi (Smith and Read, 2000) and only a relative specificity between host plants and fungal isolates (McGonigle and Fitter, 1990), the obligate nature of the symbiosis implies the establishment of a plant propagation system, either under greenhouse conditions or in vitro laboratory propagation. These techniques result in high inoculum production costs, which still remains a serious problem since they are not competitive with production costs of phosphorus fertilizer. Even if farmers understand the significance of sustainable agricultural systems, the reduction of phosphorus inputs by using AM fungal inocula alone cannot be justified except, perhaps, in the case of high value crops (Saioto and Marumoto, 2002). Nurseries, high income horticulture farmers and no-agricultural application such as rehabilitation of degraded or devegetated landscapes are examples of areas where the use of commercial inoculum is current. Another serious problem is quality of commercial available products concerning guarantee of phatogene free content, storage conditions, most effective application methods and what types to use. Besides the information provided by suppliers about its inoculum can be deceiving, as from the usually referred total counts, only a fraction may be effective for a particular plant or in specific soil conditions. Gianinazzi and Vosátka (2004) assume that progress should be made towards registration procedures that stimulate the development of the mycorrhizal industry.
Some on-farm inoculum production and application methods have been studied, allowing farmers to produce locally adapted isolates and generate a taxonomically diverse inoculum (Mohandas et al, 2004; Douds et al, 2005). However the inocula produced this way are not readily processed for mechanical application to the fields, being an obstacle to the utilization in large scale agriculture, especially row crops, moreover it would represent an additional mechanical operation with the corresponding economic and soil compaction costs.
It is well recognized that inoculation of AM fungi has a potential significance in not only sustainable crop production, but also environmental conservation. However, the status quo of inoculation is far from practical technology that can be widely used in the field. Together a further basic understanding of the biology and diversity of AM fungi is needed (Abbott at al, 1995; Saito and Marumoto, 2002).
Advances in ecology during the past decade have led to a much more detailed understanding of the potential negative consequences of species introductions and the potential for negative ecological consequences of invasions by mycorrhizal fungi is poorly understood. Schwartz et al, (2006) recommend that a careful assessment documenting the need for inoculation, and the likelihood of success, should be conducted prior to inoculation because inoculations are not universally beneficial.
Agricultural practices such as crop rotation, tillage, weed control and fertilizer apllication all produce changes in the chemical, physical and biological soil variables and affect the ecological niches available for occupancy by the soil biota, influencing in different ways the symbiosis performance and consequently the inoculum development, shaping changes and upset balance of native populations. The molecular biology tools developed in the latest years have been very important for our perception of these changes, ensuing awareness of management choice implications in AM development.
In this context, for extensive farming systems and regarding environmental and economic costs, the identification of agronomic management practices that allow controlled manipulation of the fungal community and capitalization of AM mutualistic effect making use of local inoculum, seem to be a wise option for mycorrhiza promotion and development of sustainable crop production
Formyl Peptide Receptor as a Novel Therapeutic Target for Anxiety-Related Disorders
Formyl peptide receptors (FPR) belong to a family of sensors of the immune system that detect microbe-associated molecules and inform various cellular and sensorial mechanisms to the presence of pathogens in the host. Here we demonstrate that Fpr2/3-deficient mice show a distinct profile of behaviour characterised by reduced anxiety in the marble burying and light-dark box paradigms, increased exploratory behaviour in an open-field, together with superior performance on a novel object recognition test. Pharmacological blockade with a formyl peptide receptor antagonist, Boc2, in wild type mice reproduced most of the behavioural changes observed in the Fpr2/3(-/-) mice, including a significant improvement in novel object discrimination and reduced anxiety in a light/dark shuttle test. These effects were associated with reduced FPR signalling in the gut as shown by the significant reduction in the levels of p-p38. Collectively, these findings suggest that homeostatic FPR signalling exerts a modulatory effect on anxiety-like behaviours. These findings thus suggest that therapies targeting FPRs may be a novel approach to ameliorate behavioural abnormalities present in neuropsychiatric disorders at the cognitive-emotional interface
Influence of acute pancreatitis on the in vitro responsiveness of rat mesenteric and pulmonary arteries
<p>Abstract</p> <p>Background</p> <p>Acute pancreatitis is an inflammatory disease characterized by local tissue injury and systemic inflammatory response leading to massive nitric oxide (NO) production and haemodynamic disturbances. Therefore, the aim of this work was to evaluate the vascular reactivity of pulmonary and mesenteric artery rings from rats submitted to experimental pancreatitis.</p> <p>Male Wistar rats were divided into three groups: saline (SAL); tauracholate (TAU) and phospholipase A<sub>2 </sub>(PLA<sub>2</sub>). Pancreatitis was induced by administration of TAU or PLA<sub>2 </sub>from <it>Naja mocambique mocambique </it>into the common bile duct of rats, and after 4 h of duct injection the animals were sacrificed. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP) and phenylephrine (PHE) in isolated mesenteric and pulmonary arteries were obtained. Potency (pEC<sub>50</sub>) and maximal responses (E<sub>MAX</sub>) were determined. Blood samples were collected for biochemical analysis.</p> <p>Results</p> <p>In mesenteric rings, the potency for ACh was significantly decreased from animals treated with TAU (about 4.2-fold) or PLA<sub>2 </sub>(about 6.9-fold) compared to saline group without changes in the maximal responses. Neither pEC<sub>50 </sub>nor E<sub>MAX </sub>values for Ach were altered in pulmonary rings in any group. Similarly, the pEC<sub>50 </sub>and the E<sub>MAX </sub>values for SNP were not changed in both preparations in any group. The potency for PHE was significantly decreased in rat mesenteric and pulmonary rings from TAU group compared to SAL group (about 2.2- and 2.69-fold, for mesenteric and pulmonary rings, respectively). No changes were seen in the E<sub>MAX </sub>for PHE. The nitrite/nitrate (NO<sub>x</sub><sup>-</sup>) levels were markedly increased in animals submitted to acute pancreatitis as compared to SAL group, approximately 76 and 68% in TAU and PLA<sub>2 </sub>protocol, respectively.</p> <p>Conclusion</p> <p>Acute pancreatitis provoked deleterious effects in endothelium-dependent relaxing response for ACh in mesenteric rings that were strongly associated with high plasma NO<sub>x</sub><sup>- </sup>levels as consequence of intense inflammatory responses. Furthermore, the subsensitivity of contractile response to PHE in both mesenteric and pulmonary rings might be due to the complications of this pathological condition in the early stage of pancreatitis.</p
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