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Effect of glucose-insulin-potassium infusion (GIK) on stress-induced myocardial ischaemia
No full textEffects of mild hyperinsulinaemia on conduit vessel endothelial function: role of noradrenergic activation
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Effect of mild hyperisulinemia on conduit vessel endothelial function: role of noradrenergic activation.
No full textOBJECTIVE:
The evidence that an exogenously induced modest hyperinsulinemia deteriorates conductance artery endothelial function - flow-mediated dilatation (FMD) - in healthy individuals is in contrast with in-vitro and in-vivo studies that consistently found that insulin facilitates both nitric oxide release and the endothelium-dependent dilatation. The aim of this study was to verify whether this effect is caused by the enhancement of insulin-induced adrenergic tone.
METHOD:
In 10 healthy male volunteers, endothelium-dependent (FMD) and endothelium-independent (glyceryl trinitrate, GTN) dilatation were evaluated by high-resolution ultrasound of the brachial artery, combined with a computerized edge detection system, at baseline (-60 and 0 min) and after 120 and 240 min during insulin infusion (INS study). In five participants, randomly selected from the initial group, the study was repeated during an isotonic saline (0.9% sodium chloride) intravenous infusion (SAL study). In an additional five participants, insulin infusion was preceded by an intravenous infusion of clonidine started 40 min before insulin and continued throughout the study (INS + CLN study).
RESULTS:
Plasma norepinephrine concentration increased in the INS study from 260 ± 40 to 333 ± 62 pg/ml (P < 0.05), whereas it remained stable throughout the INS + CLN study. In the INS study, no change in FMD was observed, whereas the response to GTN tended to decrease (P = 0.09). In the INS + CLN study, no significant changes in FMD response were observed, whereas GTN response was completely restored.
CONCLUSION:
Physiological hyperinsulinemia has no effect on endothelium-dependent vasodilatation in conduit vessels of healthy individuals, but it induces a slight decline in endothelium-independent vasodilatation, which is entirely explained by the insulin-induced noradrenergic activation
Effects of GIK (glucose-insulin-potassium) on stress-induced myocardial ischaemia
No full textDespite the evidence in experimental animal models that insulin, or GIK (glucose-insulin-potassium), improves left ventricular function and perfusion during both acute and chronic ischaemia, clinical studies have generated conflicting results. We tested the hypothesis that pretreatment with GIK attenuates the vascular and functional effects of stress-induced myocardial ischaemia in humans. Twenty-two patients with evidence of inducible myocardial ischaemia were enrolled; 11 patients with normal ventricular function underwent two dipyridamole echocardiography tests, and 11 with regional contractility defects from previous myocardial infarction were submitted to two ECG exercise tests combined with (201)TI myocardial perfusion scintigraphy; the tests were preceded by 60 min of either normal saline or an isoglycaemic GIK infusion. On a stress echocardiogram, a 30% reduction in the severity of ischaemia was observed. On ECG ergometry, GIK infusion slightly increased the time to ischaemia (+0.6 min, P = 0.07); however, the higher workload (+8%, P = 0.07) was achieved at a similar rate-pressure plateau. On scintigraphy, an increase in ischaemic segments (+48%, P < 0.001) was imaged mainly at the expense of viable (but non-ischaemic) and non-viable segments, which were reduced by 60%. GIK affected stress-induced left ventricular underperfusion only marginally (GIK: 39.7 +/- 2.5 compared with saline: 35.4 +/- 2.2 units, P < 0.05), but significantly improved its acute reversibility (-42 +/- 4 compared with -25 +/- 4%, P < 0.001). We conclude that GIK pretreatment attenuates the effect of ischaemia on myocardial contractility, slightly improves exercise tolerance and causes a more rapid and diffuse recovery of post-ischaemic reperfusion
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A short-term high-cholesterol diet deteriorates glucose tolerance to a different extent and through different mechanisms in controls and type 2 diabetes offspring
No full textEffects of glucose tolerance on the changes provoked by glucose ingestion in microvascular function
No full textAims/hypothesis Hyperglycaemia and hyperinsulinaemia have opposite effects on endothelium-dependent vasodilatation in microcirculation, but the net effect elicited by glucose ingestion and the separate influence of glucose tolerance are unknown. Methods In participants with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) or diabetic glucose tolerance, multiple plasma markers of both oxidative stress and endothelial activation, and forearm vascular responses (plethysmography) to intra-arterial acetylcholine (ACh) and sodium nitroprusside (SNP) infusions were measured before and after glucose ingestion. In another IGT group, we evaluated the time-course of the skin vascular responses (laser Doppler) to ACh and SNP (by iontophoresis) 1, 2 and 3 h into the OGTT; the plasma glucose profile was then reproduced by means of a variable intravenous glucose infusion and the vascular measurements repeated. Results Following oral glucose, plasma antioxidants were reduced by 5% to 10% (p<0.01) in all patient groups. The response to acetylcholine was not affected by glucose ingestion in any group, while the response to SNP was attenuated, particularly in the IGT group. The ACh:SNP ratio was slightly improved therefore in all groups, even in diabetic participants, in whom it was impaired basally. A time-dependent improvement in ACh:SNP ratio was also observed in skin microcirculation following oral glucose; this improvement was blunted when matched hyperglycaemia was coupled with lower hyperinsulinaemia (intravenous glucose). Conclusions/Interpretation Regardless of glucose tolerance, oral glucose does not impair endothelium-dependent vasodilatation either in resistance arteries or in the microcirculation, despite causing increased oxidative stress; the endogenous insulin response is probably responsible for countering any inhibitory effect on vascular function
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