Ingestion of free amino acids compared with an equivalent amount of intact protein results in more rapid amino acid absorption and greater postprandial plasma amino acid availability without affecting muscle protein synthesis rates in young adults in a double-blind randomized trial

Background The rate of protein digestion and amino acid absorption determines the postprandial rise in circulating amino acids and modulates postprandial muscle protein synthesis rates. Objective We sought to compare protein digestion, amino acid absorption kinetics, and the postprandial muscle protein synthetic response following ingestion of intact milk protein or an equivalent amount of free amino acids. Methods Twenty-four healthy, young participants (mean ± SD age: 22 ± 3 y and BMI 23 ± 2 kg/m2; sex: 12 male and 12 female participants) received a primed continuous infusion of l-[ring-2H5]-phenylalanine and l-[ring-3,5–2H2]-tyrosine, after which they ingested either 30 g intrinsically l-[1–13C]-phenylalanine–labeled milk protein or an equivalent amount of free amino acids labeled with l-[1–13C]-phenylalanine. Blood samples and muscle biopsies were obtained to assess protein digestion and amino acid absorption kinetics (secondary outcome), whole-body protein net balance (secondary outcome), and mixed muscle protein synthesis rates (primary outcome) throughout the 6-h postprandial period. Results Postprandial plasma amino acid concentrations increased after ingestion of intact milk protein and free amino acids (both P < 0.001), with a greater increase following ingestion of the free amino acids than following ingestion of intact milk protein (P-time × treatment < 0.001). Exogenous phenylalanine release into plasma, assessed over the 6-h postprandial period, was greater with free amino acid ingestion (76 ± 9%) than with milk protein treatment (59 ± 10%; P < 0.001). Ingestion of free amino acids and intact milk protein increased mixed muscle protein synthesis rates (P-time < 0.001), with no differences between treatments (from 0.037 ± 0.015%/h to 0.053 ± 0.014%/h and 0.039 ± 0.016%/h to 0.051 ± 0.010%/h, respectively; P-time × treatment = 0.629). Conclusions Ingestion of a bolus of free amino acids leads to more rapid amino acid absorption and greater postprandial plasma amino acid availability than ingestion of an equivalent amount of intact milk protein. Ingestion of free amino acids may be preferred over ingestion of intact protein in conditions where protein digestion and amino acid absorption are compromised

A multi-center blinded study on the efficiency of phenotypic screening methods to detect glycopeptide intermediately susceptible Staphylococcus aureus (GISA) and heterogeneous GISA (h-GISA)

Contains fulltext : 52338.pdf (publisher's version ) (Open Access)BACKGROUNDS: To determine the true incidence of hGISA/GISA and its consequent clinical impact, methods must be defined that will reliably and reproducibly discriminate these resistant phenotypes from vancomycin susceptible S. aureus (VSSA). METHODS: This study assessed and compared the ability of eight Dutch laboratories under blinded conditions to discriminate VSSA from hGISA/GISA phenotypes and the intra- and inter-laboratory reproducibility of agar screening plates and the Etest method. A total of 25 blinded and unique strains (10 VSSA, 9 hGISA and 6 GISA) were categorized by the PAP-AUC method and PFGE typed to eliminate clonal duplication. All strains were deliberately added in quadruplets to evaluate intra-laboratory variability and reproducibility of the methods. Strains were tested using three agar screening methods, Brain Heart Infusion agar (BHI) + 6 microg/ml vancomycin, Mueller Hinton agar (MH) + 5 microg/ml vancomycin and MH + 5 microg/ml teicoplanin) and the Etest macromethod using a 2 McFarland inoculum. RESULTS AND DISCUSSION: The ability to detect the hGISA/GISA phenotypes varied significantly between methods and phenotypes. BHI vancomycin and MH vancomycin agar screens lacked the ability to detect hGISA. The MH teicoplanin agar screen was more sensitive but still inferior to Etest that had a sensitivity of 98.5% and 99.5%, for hGISA and GISA, respectively. Intra- and inter-laboratory reproducibility varied between methods with poorest performance seen with BHI vancomycin. CONCLUSION: This is the first multi-center blinded study to be undertaken evaluating various methods to detect GISA and hGISA. These data showed that the ability of clinical laboratories to detect GISA and hGISA varied considerably, and that screening plates with vancomycin have a poor performance in detecting hGISA

PCR colorimetric dot-blot assay and clinical pretest probability for diagnosis of Pulmonary Tuberculosis in Smear-Negative patients

<p>Abstract</p> <p>Background</p> <p>Smear-negative pulmonary tuberculosis (SNPTB) accounts for 30% of Pulmonary Tuberculosis (PTB) cases reported annually in developing nations. Polymerase chain reaction (PCR) may provide an alternative for the rapid detection of <it>Mycobacterium tuberculosis </it>(MTB); however little data are available regarding the clinical utility of PCR in SNPTB, in a setting with a high burden of TB/HIV co-infection.</p> <p>Methods</p> <p>To evaluate the performance of the PCR dot-blot in parallel with pretest probability (Clinical Suspicion) in patients suspected of having SNPTB, a prospective study of 213 individuals with clinical and radiological suspicion of SNPTB was carried out from May 2003 to May 2004, in a TB/HIV reference hospital. Respiratory specialists estimated the pretest probability of active disease into high, intermediate, low categories. Expectorated sputum was examined by direct microscopy (Ziehl-Neelsen staining), culture (Lowenstein Jensen) and PCR dot-blot. Gold standard was based on culture positivity combined with the clinical definition of PTB.</p> <p>Results</p> <p>In smear-negative and HIV subjects, active PTB was diagnosed in 28.4% (43/151) and 42.2% (19/45), respectively. In the high, intermediate and low pretest probability categories active PTB was diagnosed in 67.4% (31/46), 24% (6/25), 7.5% (6/80), respectively. PCR had sensitivity of 65% (CI 95%: 50%–78%) and specificity of 83% (CI 95%: 75%–89%). There was no difference in the sensitivity of PCR in relation to HIV status. PCR sensitivity and specificity among non-previously TB treated and those treated in the past were, respectively: 69%, 43%, 85% and 80%. The high pretest probability, when used as a diagnostic test, had sensitivity of 72% (CI 95%:57%–84%) and specificity of 86% (CI 95%:78%–92%). Using the PCR dot-blot in parallel with high pretest probability as a diagnostic test, sensitivity, specificity, positive and negative predictive values were: 90%, 71%, 75%, and 88%, respectively. Among non-previously TB treated and HIV subjects, this approach had sensitivity, specificity, positive and negative predictive values of 91%, 79%, 81%, 90%, and 90%, 65%, 72%, 88%, respectively.</p> <p>Conclusion</p> <p>PCR dot-blot associated with a high clinical suspicion may provide an important contribution to the diagnosis of SNPTB mainly in patients that have not been previously treated attended at a TB/HIV reference hospital.</p

Does supplementation with leucine-enriched protein alone and in combination with fish-oil-derived n–3 PUFA affect muscle mass, strength, physical performance, and muscle protein synthesis in well-nourished older adults? A randomized, double-blind, placebo-controlled trial

peer-reviewedBackground Leucine-enriched protein (LEU-PRO) and long-chain (LC) n–3 (ω–3) PUFAs have each been proposed to improve muscle mass and function in older adults, whereas their combination may be more effective than either alone. Objective The impact of LEU-PRO supplementation alone and combined with LC n–3 PUFAs on appendicular lean mass, strength, physical performance and myofibrillar protein synthesis (MyoPS) was investigated in older adults at risk of sarcopenia. Methods This 24-wk, 3-arm parallel, randomized, double-blind, placebo-controlled trial was conducted in 107 men and women aged ≥65 y with low muscle mass and/or strength. Twice daily, participants consumed a supplement containing either LEU-PRO (3 g leucine, 10 g protein; n = 38), LEU-PRO plus LC n–3 PUFAs (0.8 g EPA, 1.1 g DHA; LEU-PRO+n–3; n = 38), or an isoenergetic control (CON; n = 31). Appendicular lean mass, handgrip strength, leg strength, physical performance, and circulating metabolic and renal function markers were measured pre-, mid-, and postintervention. Integrated rates of MyoPS were assessed in a subcohort (n = 28). Results Neither LEU-PRO nor LEU-PRO+n–3 supplementation affected appendicular lean mass, handgrip strength, knee extension strength, physical performance or MyoPS. However, isometric knee flexion peak torque (treatment effect: −7.1 Nm; 95% CI: −12.5, −1.8 Nm; P < 0.01) was lower postsupplementation in LEU-PRO+n–3 compared with CON. Serum triacylglycerol and total adiponectin concentrations were lower, and HOMA-IR was higher, in LEU-PRO+n–3 compared with CON postsupplementation (all P < 0.05). Estimated glomerular filtration rate was higher and cystatin c was lower in LEU-PRO and LEU-PRO+n–3 postsupplementation compared with CON (all P < 0.05). Conclusions Contrary to our hypothesis, we did not observe a beneficial effect of LEU-PRO supplementation alone or combined with LC n–3 PUFA supplementation on appendicular lean mass, strength, physical performance or MyoPS in older adults at risk of sarcopenia. This trial was registered at clinicaltrials.gov as NCT03429491.Horizon 2020 Framework ProgrammeThis work was supported by the Department of Agriculture, Food and the Marine Food Institutional Research Measure grant entitled NUTRIMAL “Novel Nutritional Solutions for the Prevention of Malnutrition” (grant 14F822), the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie Grant Agreement No. 666010, and a Research Fellowship awarded to CHM by the European Society of Clinical Nutrition and Metabolism (ESPEN). HMR was supported by funding from the Joint Programming Initiative Healthy Diet for a Healthy Life (JPI HDHL) EU Food Biomarkers Alliance “FOODBAll” with Science Foundation Ireland (14/JPHDHL/B3076)

Nucleolus: the fascinating nuclear body

Nucleoli are the prominent contrasted structures of the cell nucleus. In the nucleolus, ribosomal RNAs are synthesized, processed and assembled with ribosomal proteins. RNA polymerase I synthesizes the ribosomal RNAs and this activity is cell cycle regulated. The nucleolus reveals the functional organization of the nucleus in which the compartmentation of the different steps of ribosome biogenesis is observed whereas the nucleolar machineries are in permanent exchange with the nucleoplasm and other nuclear bodies. After mitosis, nucleolar assembly is a time and space regulated process controlled by the cell cycle. In addition, by generating a large volume in the nucleus with apparently no RNA polymerase II activity, the nucleolus creates a domain of retention/sequestration of molecules normally active outside the nucleolus. Viruses interact with the nucleolus and recruit nucleolar proteins to facilitate virus replication. The nucleolus is also a sensor of stress due to the redistribution of the ribosomal proteins in the nucleoplasm by nucleolus disruption. The nucleolus plays several crucial functions in the nucleus: in addition to its function as ribosome factory of the cells it is a multifunctional nuclear domain, and nucleolar activity is linked with several pathologies. Perspectives on the evolution of this research area are proposed

Commercial Nucleic-Acid Amplification Tests for Diagnosis of Pulmonary Tuberculosis in Respiratory Specimens: Meta-Analysis and Meta-Regression

BACKGROUND: Hundreds of studies have evaluated the diagnostic accuracy of nucleic-acid amplification tests (NAATs) for tuberculosis (TB). Commercial tests have been shown to give more consistent results than in-house assays. Previous meta-analyses have found high specificity but low and highly variable estimates of sensitivity. However, reasons for variability in study results have not been adequately explored. We performed a meta-analysis on the accuracy of commercial NAATs to diagnose pulmonary TB and meta-regression to identify factors that are associated with higher accuracy. METHODOLOGY/PRINCIPAL FINDINGS: We identified 2948 citations from searching the literature. We found 402 articles that met our eligibility criteria. In the final analysis, 125 separate studies from 105 articles that reported NAAT results from respiratory specimens were included. The pooled sensitivity was 0.85 (range 0.36-1.00) and the pooled specificity was 0.97 (range 0.54-1.00). However, both measures were significantly heterogeneous (p<.001). We performed subgroup and meta-regression analyses to identify sources of heterogeneity. Even after stratifying by type of commercial test, we could not account for the variability. In the meta-regression, the threshold effect was significant (p = .01) and the use of other respiratory specimens besides sputum was associated with higher accuracy. CONCLUSIONS/SIGNIFICANCE: The sensitivity and specificity estimates for commercial NAATs in respiratory specimens were highly variable, with sensitivity lower and more inconsistent than specificity. Thus, summary measures of diagnostic accuracy are not clinically meaningful. The use of different cut-off values and the use of specimens other than sputum could explain some of the observed heterogeneity. Based on these observations, commercial NAATs alone cannot be recommended to replace conventional tests for diagnosing pulmonary TB. Improvements in diagnostic accuracy, particularly sensitivity, need to be made in order for this expensive technology to be worthwhile and beneficial in low-resource countries