101,864 research outputs found
A RADIOMETRIC ASSAY FOR GANGLIOSIDE SIALIDASE APPLIED TO THE DETERMINATION OF THE ENZYME SUBCELLULAR LOCATION IN CULTURED HUMAN-FIBROBLASTS
No full textA radiometric method for the assay of ganglioside sialidase in cultured human fibroblasts was set up. As substrate, highly radioactive (1.28 Ci/mmol) ganglioside GD1a isotopically tritium-labeled at carbon C-3 of the long chain base was employed; the liberated, and TLC separated [3H]GM1 was determined by computer-assisted radiochromatoscanning. Under experimental conditions that provided a low and quite acceptable (4-5%) coefficient of variation, the detection limit of the method was 0.1 nmol of liberated GM1, using as low as 10 μg of fibroblast homogenate as protein. The detection limit could be lowered to 0.02-0.03 nmol, adopting conditions that, however, carried a higher analytical error (coefficient of variation over 10%). The content of ganglioside sialidase in human fibroblasts cultured in 75-cm2 plastic flasks was 5.8 ∓ 2.5 (SD) nmol liberated GM1 h-1 mg protein-1. Subfractionation studies performed on fibroblast homogenate showed that the ganglioside sialidase was mainly associated with the light membrane subfraction that was rich in plasma and intracellular membranes. This subfraction displayed almost no sialidase activity on the artificial substrate 4-methylumbelliferyl-d-N-acetylneuraminic acid. A small but measurable ganglioside sialidase activity was also present in the lysosome-enriched subfraction, which contained a very high sialidase activity on the above artificial substrate. All this supports the hypothesis that human fibroblasts contain sialidases with different subcellular location and substrate specificity. Particularly, the sialidase acting on gangliosides seems to have two sites of subcellular location, a major one at the level of plasma membranes and/or intracellular organelles functionally related with the plasma membranes and a minor one in the lysosomes
Transintestinal transport of L-carnitine and carnitine esters in the rat
No full textL-carnitine is transported in small intestine via a carrier-mediate active transport system. At pharmacological doses a diffusional component is predominant
L-carnitine and carnitine ester transport in the rat small intestine
No full textL-Carnitine and its esters (acetyl-L-carnitine and propionyl-L-carnitine) at pharmacological doses (1,5 and 100 mM) are absorbed by the rat jejunum by simple diffusion. Partition coefficients of carnitin eesters determined in lipophilic media (diethyl ether/water and olive oil/water) are greater than that of L-carnitine. It would therefore seem that esters diffuse more easily through th elipid component of the intestinal barrier. The transport of acetyl- and propionyl-L-carnitine at pharmacological doses seems to be linearly and positively correlated with K+ transport but not with Na+ transport
HEMODYNAMIC AND METABOLIC-ACTIVITIES OF PROPIONYL-L-CARNITINE IN RATS WITH PRESSURE-OVERLOAD CARDIAC-HYPERTROPHY
No full textEvidence has been put forth that a number of human and experimental cardiomyopathies are associated with a lower myocardial carnitine content. This study was performed to test the hypothesis that the correction of carnitine deficiency by a naturally occurring carnitine derivative, propionyl-L-carnitine (PLC), may improve cardiac function. Repeated administration of PLC was compared to saline with respect to cardiac function in rats with pressure-overload cardiac hypertrophy and low myocardial carnitine levels. Cardiac hypertrophy was induced by abdominal aorta constriction in rats. Separate groups of rats were used for (a) determination of myocardial carnitine content, (b) evaluation of in vivo hemodynamics, and (c) evaluation of performance and metabolic state of Langendorff perfused hearts. Results showed the following: (i) The myocardial carnitine content was inversely correlated to cardiac hypertrophy (r = 0.68, p 1,400 mg, the effect of PLC on CO, CW, SV, SW, and total peripheral resistance (TPR) was significantly different from that of saline (CO, CW, SV, and SW, p < 0.005 each; TPR, p < 0.05). The effect was observed 24 h after the first PLC administration and significantly diminished following a 4 day suspension of the treatment. (iii) Perfused hearts from PLC-treated rats displayed a significantly lower left ventricular end- diastolic pressure (p < 0.01) and greater relaxation rate (p < 0.05) than those from control rats. Moreover, in PLC-treated hearts, the content of creatine phosphate, ATP, and total adenine nucleotides (ATP + ADP + AMP; TAN) was significantly increased (CP, p < 0.05; ATP and TAN, p < 0.01 vs. control). These data show that PLC exerts a stimulatory activity on hearts with hypertrophy and low carnitine content, implying that carnitine deficiency may contribute to the depression of cardiac function in this model
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
The Right to Strike under the United States Constitution: Theory, Practice, and Possible Implications for Canada
No full textAnswering critics of the Canadian Supreme Court's judgment in B.C. Health, the author argues that the Court laid the foundation for a principled and durable doctrine protecting constitutional labour rights, one that goes directly to the heart of the matter — the inequality of workers’ power in the employment relation. In the author’s view, two paths could lead from B.C. Health to the recognition of Charter protec- tion for a right to strike: one that treats the right as an accessory to col- lective bargaining, and one that upholds the right directly on the basis of the Charter values of equality and participation. The author supports the latter approach, contending that constitutional rights should be defined in relation to fundamental values, in a way that is not contingent on time-bound or fact-sensitive assessments about the role of strikes within a particular collective bargaining regime. Although a Charter right to strike may involve the courts in difficult choices about when to defer to legislative policy decisions, and courts may lack the institutional capac- ity to deal effectively with labour law issues, the author points out that judges can look to ILO standards for expert guidance. Noting that the U.S. experience in this area might be of considerable use to Canadians, the author concludes by providing an overview of American case law concerning a constitutional right to strike.Peer reviewe
Plasma concentration, urinary excretion and renal clearance of L-carnitine during pregnancy: a reversible secondary L-carnitine deficiency.
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