117,445 research outputs found
Bis(L-Amino Acid Amidato)Copper(II) Complexes as Chiral Eluents in the Enantiomeric Separation of D,L-Dansylamino Acids by Reversed-Phase High-Performance Liquid Chromatography
No full textGlucose kinetics and splanchnic uptake following mixed meal ingestion in cirrhotic-diabetic subjects.
No full textAlthough glucose intolerance and/or overt diabetes are common in cirrhotic
subjects, the mechanism(s) that lead to post-prandial hyperglycemia in cirrhosis
are not entirely known. To this aim, we measured whole-body rates of glucose
appearance (Ra) and of disappearance (Rd) in cirrhotic-diabetic subjects and in
controls, before and following a 4-hr administration of a mixed meal. In the
post-prandial phase, endogenous and dietary glucose Ra, as well as first-pass
splanchnic uptake of dietary glucose, were measured using a double (ie oral and
intravenous) glucose tracer technique. In the fasting state, the cirrhotic
patients were hyperglycemic (12.0 +/- 1.4 vs 4.4 +/- 0.2 mmol/l in controls, p <
0.001), had a higher glucose Ra (17.0 +/- 2.7 vs 10.2 +/- 0.5 micromol x kg(-1) x
min(-1), p < 0.05) and a lower clearance rate (1.51 +/- 0.19 vs 2.32 +/- 0.06 ml
x kg x min, p < 0.02). Following the meal, plasma glucose increased to greater
values (p < 0.002) in the patients (to 16.8 +/- 2 mmol/l, mean values of the last
40 min) than in the controls (to 7.2 +/- 0.4 mmol/l). Insulin increased in both
groups but it was 35% lower (p > 0.05) in the patients. Post-prandial total
glucose Ra (cirrhotics: 21.3 +/- 2.6; controls: 19.2 +/- 1.4 pmol x kg(-1) x
min(-1)), endogenous Ra (cirrhotics: 7.3 +/- 1.5; controls: 7.0 +/- 1.3 micromol
x kg(-1) x min(-1)) and first-pass splanchnic uptake of dietary glucose
(cirrhotics: 9.8 +/- 2.6; controls: 11.5 +/- 1.6 micromol x kg x min(-1)), were
not different between the 2 groups, whereas glucose clearance remained lower
(p<0.001) in the patients (1.31 +/- 0.25 ml x kg(-1) x min)-1)) than in the
controls (2.72 +/- 0.26). These data demonstrate that, in cirrhotic-diabetic
patients, post-pran-dial hyperglycemia is not due to a reduced extraction of
dietary glucose nor to an increased endogenous production, but rather to a defect
in peripheral glucose clearance, secondary to either insulin-resistance and/or
relative insulin deficienc
Differences in estimates of forearm protein synthesis between leucine and phenylalanine tracers following unbalanced amino acid infusion.
No full textWe compared the leucine (Leu) and phenylalanine (Phe) tracer-determined response
of forearm protein synthesis (PS) before and after stimulation of protein
anabolism by intravenous infusion of Leu-enriched, Phe-deficient amino acids and
insulin (increased to approximately 100 microU/mL) with the euglycemic clamp. Six
healthy subjects received primed-constant infusions of L-[ring-2H5]-Phe and
L-[1-(14)C]-Leu, and steady-state forearm Phe and Leu kinetics were determined.
Following the combined infusion, the arterial Leu concentration increased
approximately 70% (P < .001), whereas Phe decreased about 15% (P < .01). Forearm
PS and net balance (NB) increased (P < .05 or less v basal) using both amino acid
tracers. However, the relative increments observed with the Leu tracer were more
than 75% larger (P < .05 or less) than those observed with the Phe tracer, even
when the data were corrected for the standard relative abundance of these two
amino acids in forearm protein(s). Thus, the calculated changes of forearm PS and
NB in response to an unbalanced amino acid infusion with hyperinsulinemia were
affected by the plasma level of leucine and phenylalanine, whose tracers were
used to estimate forearm protein turnover. Since these two essential amino acids
share the same transport system, a competition at this level cannot be exclude
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
Protein metabolism in glucagonoma.
No full textAlthough protein wasting and reduced amino acid concentrations are common findings in glucagonoma patients, the mechanisms underlying these alterations are unclear. Therefore, we studied basal postabsorptive leucine, phenylalanine and tyrosine turnover following L-[D3]-Leucine, L-[D5]-Phenylalanine and L-[D2]-Tyrosine i.v. infusions in one male and one female patient with glucagonoma, compared with healthy control volunteers. Plasma amino acid concentrations were reduced (-40 to 80%, delta >2 SD vs. control subjects) in both patients. Plasma leucine, phenylalanine and tyrosine rates of appearance in patients with glucagonoma were similar to values in the control subjects, except leucine rate of appearence in the female patient with glucagonoma (+ approximately 30%, delta >2 SD). In contrast, the intracellular leucine rate of appearence, reflecting protein degradation, was considerably increased in both patients (+60-80%, delta >2 SD). Phenylalanine hydroxylation was moderately higher only in the male patient with glucagonoma (+ approximately 30%, delta >2 SD). Leucine, phenylalanine and tyrosine clearances (+100-300%), as well as phenylalanine hydroxylative clearance (+75-100%) were also increased in the patients. In conclusion, whole-body protein breakdown is enhanced in patients with glucagonoma compared with healthy control subjects. Phenylalanine hydroxylative clearance is also higher. Reduced plasma amino acid concentrations are probably due, at least in part, to their increased clearance. These alterations could contribute to the determination of the catabolic state of the glucagonoma syndrome
Relationships between phenylalanine hydroxylation and plasma aromatic amino acid concentrations in humans.
No full textWe investigated the relationships between phenylalanine hydroxylation (Phe Hy) and plasma concentrations of phenylalanine, tyrosine, and glucagon in healthy male volunteers (N = 13; age, 29 +/- 3 years). Phe Hy, as well as the Phe and Tyr rate of appearance (Ra), were measured during L-[2H5]-Phe and L-[2H2]-Tyr continuous intravenous (i.v.) infusions both under basal postabsorptive conditions (N = 13) and following divergent changes of plasma aromatic amino acids (AAA) concentrations. Namely, AAA were increased by administration of a balanced synthetic mixed meal (n = 6) or selectively decreased by i.v. infusion of insulin along with a Phe-deficient, Tyr and tryptophan-deprived amino acid mixture ([IAA] n = 7). Following the meal, plasma Phe (54 +/- 3 to 81 +/- 12 micromol/L), plasma Tyr (54 +/- 4 to 91 +/- 7), Phe Hy (0.09 +/- 0.01 to 0.15 +/- 0.02 micromol/kg x min), Phe Ra (0.65 +/- 0.04 to 0.96 +/- 0.07), and Tyr Ra (0.51 +/- 0.03 to 0.93 +/- 0.11) all significantly increased (P < or = .05 v basal). IAA infusion significantly decreased plasma Phe (to 47 +/- 3 micromol/L), plasma Tyr (to 25 +/- 4), Phe Hy (to 0.07 +/- 0.004 micromol/kg x min), and Tyr Ra (to 0.29 +/- 0.02; all P < or = .05 v sal), while Phe Ra did not change (0.64 +/- 0.04, NS). Plasma glucagon did not change in the three experimental periods (basal, 85 +/- 7; meal, 72 +/- 10; IAA, 92 +/- 14 pg/mL; NS). Using linear regression analysis, plasma Phe was positively related to both Phe Hy (R2 = .76, P < .001) and plasma Tyr (R2 = .80, P < .001); Phe Hy and plasma Tyr were also significantly correlated (R2 = .60, P < .001). No correlation was found between Phe Hy and basal plasma glucagon (R2 = .04, NS). Using multiple regression analysis with plasma Tyr as the dependent variable, plasma Phe was still correlation with plasma Tyr (t = 4.29, P = .0002), while the relationship between Phe Hy and plasma Tyr was no longer significant (t = 0.69, P = .49). These data indicate that plasma Phe is closely associated with its own hydroxylative disposal in humans, and confirm that Phe conversion to Tyr may play a physiological role in maintaining balanced plasma phenylalanine and tyrosine concentrations
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
Therapeutic strategies for sarcopenic obesity: a systematic review
No full textPURPOSE OF REVIEW: Tough plenty of literature investigated therapeutic options for body composition changes targeting elderly people, evidence concerning potential treatments of sarcopenic obesity as a unique condition is scarce. The aim of the present review was to summarize recent evidence regarding treatment of sarcopenic obesity in adult and older individuals. RECENT FINDINGS: Exercise-based interventions were effective in ameliorating lean mass or sarcopenia-related indices and reducing total adiposity. Importantly, in one study, modifications of body composition were obtained in the absence of significant changes in body mass index. The majority of studies relied on resistance training, and all provided with beneficial effects in body composition. Conversely, effects in terms of muscle strength and functional ability were heterogeneous. Electrical acupuncture and whole-body electromyostimulation associated with nutritional supplementation resulted to be novel effective strategies in inducing body composition changes. Nonetheless, findings from nutritional supplementations are not conclusive, leading to conflicting results on strength and functional outcomes. SUMMARY: Specific interventions could improve sarcopenic obesity, but overall significance is limited by scarcity of data and lack of uniformity in the definition of sarcopenic obesity itself. Further research should clarify optimal treatment options for sarcopenic obesity in age classes other than the geriatric population
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
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