117,387 research outputs found
Bis(diamido)-bridged basket resorcin[4]arenes as enantioselective receptors for amino acids and amines
No full textBotta B, D'Acquarica F, Nevola L, et al. Bis(diamido)-bridged basket resorcin[4]arenes as enantioselective receptors for amino acids and amines. European Journal of Organic Chemistry. 2007;2007(36):5995-6002.On the research avenue opened by the rigidified double-spanned resorcin[4]arene 1, we have synthesized both enantiomers of the two chiral basket resorcin[4]arenes 3 and 4, each containing two 1,2-diaminocyclohexane and 1,2-diphenylethylenediamine bridges, respectively. In the new compounds, the aromatic rims assume the expected flattened cone arrangement, whereas two different conformations, tentatively designated as "open wings" and "folded wings", were attributed to the bridge substituents according to molecular modeling studies. In MSn (ESI) experiments, the proton-bonded diastereomeric [4.H.A](+) complexes with amino acidic guests (A) exhibited a pronounced selectivity towards the enantiomers of tyrosine methyl ester (tyr(OMe)) and amphetamine (amph), whereas the chirality of tryptophan (trp) was ineffective. Moreover, a kinetic study on the base-induced displacement of the guest revealed that the L-tyr(OMe) (and L-amph) enantiomer is faster displaced from the heterochiral [4.H.L-tyr(OMe)](+) (or [ent-4.H.L-amph](+)) complex than from the homochiral [ent-4.H.L-tyr(OMe)](+) (or [4.H.L-amph](+)) one. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007
Left ventricular mass increase is associated with cognitive decline and dementia in the elderly independently of blood pressure
No full textAIMS: Left ventricular (LV) mass increase is considered part of composite target organ damage in hypertension and an independent risk factor for cardiovascular (CV) events. This study was designed to explore whether left ventricular mass index (LVMI) is associated with cognitive decline and dementia in elderly subjects, independently of blood pressure (BP) levels. METHODS AND RESULTS: Four hundred subjects (mean age 79 +/- 6 years) were studied. Left ventricular mass was measured echocardiographically in accordance with American Society of Echocardiography and normalized for body height to the 2.7 (LVMI). Global cognitive function was evaluated with the mini-mental state examination (MMSE) (maximum score 30). Dementia was defined as an MMSE score <21. Arterial stiffness was evaluated as carotid-femoral pulse wave velocity by Complior. Prevalence of hypertension was 70% and diabetes mellitus was diagnosed in 25%. No significant differences in traditional CV risk factors were observed across LVMI quartiles. Mini-mental state examination showed an inverse trend across LVMI quartiles (the higher the LVMI, the lower the MMSE, P for trend <0.05); systolic and diastolic BP levels were not different across LVMI quartiles. In multivariable logistic regression models, including age, sex, BP levels, and use of antihypertensive drugs as covariates, the highest LVMI was found to be independently associated with a two-fold higher likelihood of having dementia. The association persisted significant even after adjustment for arterial stiffness. CONCLUSION: In elderly subjects, LVMI is associated with a progressive cognitive decline. This association is independent of BP levels and/or large artery stiffness
Hepatocellular carcinoma and non-alcoholic fatty liver disease: a dangerous liaison
No full texte1299-Hepatocellular carcinoma and non-alcoholic fatty liver disease-a dangerous liaisonLiver cancer is one of the most frequent malignancies in the world, and its incidence rates are on the rise. Due to the global epidemic of metabolic syndrome, the incidence of hepatocellular carcinoma (HCC) secondary to non-alcoholic fatty liver disease (NAFLD) is increasing, contrary to viral forms. Characteristically NAFLD-related HCCs tend to occur at the earlier stages of liver disease, while often the diagnosis of neoplasia occurs later. They also affect an averagely older population, generally with a significantly higher number of co-morbidities. For these reasons, curative treatments are seldom applicable. Therefore, this work aims to illustrate the current state of knowledge on the NAFLD-related HCC and to underline the known pathogenetic mechanisms
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Increases in walking distance in patients with peripheral vascular disease treated with L-carnitine: A double-blind, cross-over study
No full textA double-blind, cross-over study was designed to evaluate the effects of L-carnitine in patients with peripheral vascular disease. After drug washout, 20 patients were randomly assigned to receive placebo or L-carnitine (2 g bid, orally) for a period of 3 weeks and were then crossed over to the other treatment for an additional 3 weeks. The effect on walking distance at the end of each treatment period was measured by treadmill test. Absolute walking distance rose from 174 ± 63 m with placebo to 306 ± 122 m (p < .01) with carnitine. Biopsy of the ischemic muscle, carried out before and after 15 days of L-carnitine administration in four additional patients, showed that treatment significantly increased total carnitine levels. An additional goal of this study was to ascertain the effects of L-carnitine on the metabolic changes induced by exercise in the affected limb. In six patients under control conditions, arterial and popliteal venous lactate and pyruvate concentrations were determined at rest, when the maximal walking distance was reached, and 5 min after the walking test. Twenty-four hours later, L-carnitine was administered intravenously (3 g as a bolus followed by an infusion of 2 mg/kg/min for 30 min) and metabolic assessments were repeated. Five minutes after the walking test, popliteal venous lactate concentration increased by 107 ± 16% before treatment and by only 54 ± 32% (p < .01) after carnitine. Furthermore, carnitine induced a more rapid recovery to the resting value of the lactate/pyruvate ratio. These data suggest that carnitine improves pyruvate utilization and oxidative phosphorylation efficiency in the skeletal muscle of the ischemic leg. L-Carnitine, administered intravenously to 18 patients at the same dosage as above, did not modify blood flow or the ankle/arm systolic blood pressure ratio. In an additional eight patients, this intravenous dose produced an increase in walking distance similar to that observed with oral treatment. In conclusion, this study demonstrates that L-carnitine, although not affecting the general or regional hemodynamics, improves the walking capacity of patients with intermittent claudication, probably through a metabolic mechanism
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Gaseous- versus solution-phase recognition of some aromatic amino esters by 2,8,14,20-tetrakis(L-valinamido)[4]resorcinarene
No full textThe effects of the physical environment on the molecular recognition of some aromatic amino esters (A = 3-(3,4)dihydroxyphenyl)alanine methyl ester (DOPAOMe), 3-(3,4)dihydroxyphenyl)alanine ethyl ester (DOPAOEt) and tryptophan ethyl ester (trpOEt)) by the flattened-cone 2,8,14,20- tetrakis(L-valinamido)[4]resorcinarene (1L) have been investigated in both the gas-phase by ESI-MS spectrometry and in CDCl3 solutions by 1H and 13C NMR spectroscopy. It is found that the non-covalent [1L·H·DOPAOMe]+ and [1L·H·DOPAOEt]+ complexes are stable in the gas-phase. The last one is stable in CDCl3 solutions as well, while [1L·H·trpOEt]+ is not. The formation of the stable [1L·H·DOPAOEt]+ complex in CDCl3 is not affected by the presence of traces of additives, like D2O, DCl or ethyl acetate, or by absorption on silica. APT-13C NMR analysis of [1L·H·DOPAOEt]+ suggests that the amino ester is mainly located inside the resorcinarene cavity, in conformity with the most stable structure arising from MC/MD simulations
Depression is associated with increased occurrence of left ventricle concentric geometry in older subjects independently of blood pressure levels
No full textBackground and Aim: Depression is emerging as an independent risk factor for CV events, though mechanisms underlying this association are unknown. We investigated the relation between depression and LV hypertrophy (LVH) and LV structure in a group of elderly subjects. Methods and Results: Three hundred seventy patients (mean age 79 +/- 6 years) were enrolled. CV risk factors were assessed. Depression was defined as a score >= 6 on the 15-item Geriatric Depression Scale. On the basis of the presence of LVH and of LV relative wall thickness (RWT) 4 echocardiographic patterns of LV adaptation were defined: concentric LVH (LVH with increased RWT); eccentric LVH (LVH with normal RWT); concentric LV remodeling (no LVH with increased RWT); normal LV (no LVH with normal RWT). Prevalence of hypertension was approximately 86% and 24.7% had diabetes (n.s. depressed vs not depressed subjects). BP was comparable in these two groups (134.7 +/- 1.4 vs 135.3 +/- 1.8 mmHg, 77.1 +/- 0.8 vs 76.3 +/- 1.0 mmHg for SBP and DBP respectively). Depressed subjects (n = 165) showed a significantly higher occurrence of concentric LVH than not depressed, after adjustment for age, sex, and hypertension. Depression was associated with a 2.1 fold higher risk of showing a LV concentric, either remodeling or LVH, pattern after adjustment for age, sex, and traditional CV risk factors. Conclusions: Depression is accompanied by a higher occurrence of concentric LVH in elderly subjects, independently of BP levels. (C) 2010 Elsevier B.V. All rights reserved
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