A Low or High Physical Activity Level Does Not Modulate Prostate Tumor Tissue Protein Synthesis Rates

INTRODUCTION

Physical activity level has been identified as an important factor in the development and progression of various types of cancer. In this study, we determined the impact of a low versus high physical activity level on skeletal muscle, healthy prostate, and prostate tumor protein synthesis rates in vivo in prostate cancer patients.

METHODS

Thirty prostate cancer patients (age, 66 ± 5 yr; body mass index, 27.4 ± 2.9 kg·m -2 ) were randomized to a low (<4000 steps per day, n = 15) or high (>14,000 steps per day, n = 15) physical activity level for 7 d before their scheduled radical prostatectomy. Daily deuterium oxide administration was combined with the collection of plasma, skeletal muscle, nontumorous prostate, and prostate tumor tissue during the surgical procedure to determine tissue protein synthesis rates throughout the intervention period.

RESULTS

Daily step counts averaged 3610 ± 878 and 17,589 ± 4680 steps in patients subjected to the low and high physical activity levels, respectively ( P < 0.001). No differences were observed between tissue protein synthesis rates of skeletal muscle, healthy prostate, or prostate tumor between the low (1.47% ± 0.21%, 2.74% ± 0.70%, and 4.76% ± 1.23% per day, respectively) and high (1.42% ± 0.16%, 2.64% ± 0.58%, and 4.72% ± 0.80% per day, respectively) physical activity group (all P > 0.4). Tissue protein synthesis rates were nearly twofold higher in prostate tumor compared with nontumorous prostate tissue.

CONCLUSIONS

A short-term high or low physical activity level does not modulate prostate or prostate tumor protein synthesis rates in vivo in prostate cancer patients. More studies on the impact of physical activity level on tumor protein synthesis rates and tumor progression are warranted to understand the potential impact of lifestyle interventions in the prevention and treatment of cancer.

Low Levels of Serum and Intracellular Vitamin C in Hospitalized COVID-19 Patients

Vitamin C is a crucial micronutrient for human immune cell function and has potent antioxidant properties. It is hypothesized that vitamin C serum levels decline during infection. However, the precise mechanisms remain unknown. To gain deeper insights into the true role of vitamin C during infections, we aimed to evaluate the body's vitamin C storage during a SARS-CoV-2 infection. In this single-center study, we examined serum and intracellular vitamin C levels in peripheral blood mononuclear cells (PBMCs) of 70 hospitalized COVID-19 patients on the first and fifth days of hospitalization. Also, clinical COVID-19 severity was evaluated at these timepoints. Our findings revealed a high prevalence of hypovitaminosis C and vitamin C deficiency in hospitalized COVID-19 patients (36% and 15%). Moreover, patients with severe or critical disease exhibited a higher prevalence of low serum vitamin C levels than those with moderate illness. Serum vitamin C levels had a weak negative correlation with clinical COVID-19 severity classification on the day of hospitalization; however, there was no correlation with intracellular vitamin C. Intracellular vitamin C levels were decreased in this cohort as compared to a healthy cohort and showed further decline during hospitalization, while serum levels showed no relevant change. Based on this observation, it can be suggested that the reduction of intracellular vitamin C may be attributed to its antioxidative function, the need for replenishing serum levels, or enhanced turnover by immune cells. These data give an incentive to further investigate the role of intracellular vitamin C in a larger and more heterogeneous cohort as well as the underlying mechanisms.

No Effect of Vitamin C Administration on Neutrophil Recovery in Autologous Stem Cell Transplantation for Myeloma or Lymphoma: A Blinded, Randomized Placebo-Controlled Trial

Vitamin C is an important micronutrient for various immune cells. It increases phagocytic cell function and is necessary for T and natural killer (NK) cell development. Patients in need of an autologous hematopoietic stem cell transplantation (HSCT) are often vitamin C-depleted. We therefore hypothesized that vitamin C supplementation could improve immune recovery in autologous HSCT patients. This blinded, placebo-controlled trial included 44 patients randomized to receive vitamin C or a placebo. The following outcome measures used were clinical and immunological parameters, among others: time to neutrophil recovery, serum, and intracellular vitamin C values. Twenty-one patients received vitamin C, and 23 received a placebo. The time to neutrophil recovery did not differ between the two groups at 11.2 days (p = 0.96). There were no differences in hospitalization time (19.7 vs. 19.1 days, p = 0.80), the incidence of neutropenic fever (57% vs. 78%, p = 0.20), or 3-month overall survival (90.5% vs. 100%, p = 0.13). Bacteremia seemed to occur less in the vitamin C group (10% vs. 35%, p = 0.07). Our study shows no benefit from vitamin C supplementation on neutrophil recovery and hospitalization, despite possible lower rates of bacteremia in the vitamin C group. Therefore, we do not advise vitamin C supplementation in this treatment group.

Cardiac Troponin T: The Impact of Posttranslational Modifications on Analytical Immunoreactivity in Blood up to the Excretion in Urine

Cardiac troponin T (cTnT) is a sensitive and specific biomarker for detecting cardiac muscle injury. Its concentration in blood can be significantly elevated outside the normal reference range under several pathophysiological conditions. The classical analytical method in routine clinical analysis to detect cTnT in serum or plasma is a single commercial immunoassay, which is designed to quantify the intact cTnT molecule. The targeted epitopes are located in the central region of the cTnT molecule. However, in blood cTnT exists in different biomolecular complexes and proteoforms: bound (to cardiac troponin subunits or to immunoglobulins) or unbound (as intact protein or as proteolytic proteoforms). While proteolysis is a principal posttranslational modification (PTM), other confirmed PTMs of the proteoforms include N-terminal initiator methionine removal, N-acetylation, O-phosphorylation, O-(N-acetyl)-glucosaminylation, N(ɛ)-(carboxymethyl)lysine modification and citrullination. The immunoassay probably detects several of those cTnT biomolecular complexes and proteoforms, as long as they have the centrally targeted epitopes in common. While analytical cTnT immunoreactivity has been studied predominantly in blood, it can also be detected in urine, although it is unclear in which proteoform cTnT immunoreactivity is present in urine. This review presents an overview of the current knowledge on the pathophysiological lifecycle of cTnT. It provides insight into the impact of PTMs, not only on the analytical immunoreactivity, but also on the excretion of cTnT in urine as one of the waste routes in that lifecycle. Accordingly, and after isolating the proteoforms from urine of patients suffering from proteinuria and acute myocardial infarction, the structures of some possible cTnT proteoforms are reconstructed using mass spectrometry and presented.

P4503A multi-site coronary vein sampling study on cardiac troponin T degradation in non-ST-elevation myocardial infarction

Background

High-sensitivity cardiac troponin (hs-cTn) assays have reduced specificity for myocardial infarction (MI). In conditions other than MI, cardiac troponin T (cTnT) elevations have been attributed to small cTnT fragments. In search of improved cTnT assay specificity for MI, determination of the in-vivo molecular appearance of cTnT during MI is pivotal.

Purpose

To determine cTnT composition close to its site of release and during the course of MI by multi-site coronary venous system (CVS) and peripheral sampling.

Methods

Lithium-heparinized (LH) plasma and serum samples were obtained from multiple CVS locations in NSTEMI patients. Additionally, samples were drawn from a peripheral artery and vein followed by collections at 6- and 12 hours post-catheterization. cTnT concentrations were measured using the hs-cTnT immunoassay (Roche). The molecular cTnT composition was determined by gel filtration chromatography and Western blotting in an early and late presenting patient.

Results

CVS hs-cTnT concentrations were 28% higher than in the peripheral artery sample (n=71, p<0.001). In contrast to LH plasma, serum caused pre-analytical cTn T-I-C complex disintegration and cTnT degradation. CVS samples demonstrated presence of cTn T-I-C complex, free intact cTnT, and 29 kDa and 15–18 kDa cTnT fragments in higher absolute concentrations than measured peripherally. While the proportion of cTn T-I-C complex decreased and disappeared over time, 15–18 kDa cTnT fragments increased. Moreover, cTn T-I-C complex was more prominent in the early versus the late presenting patient.

Central illustration

Conclusions

In NSTEMI, cTnT is released as a combination of cTn T-I-C complex, free intact cTnT and multiple cTnT fragments. Over time, the composition of observed cTnT forms changes due to in-vivo degradation. These findings serve as a stepping stone to improve diagnostic accuracy of the hs-cTnT assay for MI.

Leucine coingestion augments the muscle protein synthetic response to the ingestion of 15 g of protein following resistance exercise in older men

Older adults have shown an attenuated postexercise increase in muscle protein synthesis rates following ingestion of smaller amounts of protein compared with younger adults. Consequently, it has been suggested that older adults require the ingestion of more protein to increase postexercise muscle protein synthesis rates compared with younger adults. We investigated whether coingestion of 1.5 g of free leucine with a single 15-g bolus of protein further augments the postprandial muscle protein synthetic response during recovery from resistance-type exercise in older men. Twenty-four healthy older men (67 ± 1 yr) were randomly assigned to ingest 15 g of milk protein concentrate (MPC80) with (15G+LEU; n = 12) or without (15G; n = 12) 1.5 g of free leucine after performing a single bout of resistance-type exercise. Postprandial protein digestion and amino acid absorption kinetics, whole body protein metabolism, and postprandial myofibrillar protein synthesis rates were assessed using primed, continuous infusions with l-[ring-²H₅]phenylalanine, l-[ring-²H₂]tyrosine, and l-[1-¹³C]leucine combined with ingestion of intrinsically l-[1-¹³C]phenylalanine-labeled milk protein. A total of 70 ± 1% (10.5 ±0.2 g) and 75 ± 2% (11.2 ± 0.3 g) of the protein-derived amino acids were released in the circulation during the 6-h postexercise recovery phase in 15G+LEU and 15G, respectively (P < 0.05). Postexercise myofibrillar protein synthesis rates were 16% (0.058 ± 0.003 vs. 0.049 ± 0.002%/h, P < 0.05; based on l-[ring-²H₅]phenylalanine) and 19% (0.071 ± 0.003 vs. 0.060 ± 0.003%/h, P < 0.05; based on l-[1-¹³C]leucine) greater in 15G+LEU compared with 15G. Leucine coingestion further augments the postexercise muscle protein synthetic response to the ingestion of a single 15-g bolus of protein in older men.

Multi-Site Coronary Vein Sampling Study on Cardiac Troponin T Degradation in Non-ST-Segment-Elevation Myocardial Infarction: Toward a More Specific Cardiac Troponin T Assay

Background Cardiac troponin T ( cTnT ) is seen in many other conditions besides myocardial infarction, and recent studies demonstrated distinct forms of cTnT . At present, the in vivo formation of these different cTnT forms is incompletely understood. We therefore performed a study on the composition of cTnT during the course of myocardial infarction, including coronary venous system sampling, close to its site of release. Methods and Results Baseline samples were obtained from multiple coronary venous system locations, and a peripheral artery and vein in 71 non- ST -segment-elevation myocardial infarction patients. Additionally, peripheral blood was drawn at 6- and 12-hours postcatheterization. cTnT concentrations were measured using the high-sensitivity- cTnT immunoassay. The cTnT composition was determined via gel filtration chromatography and Western blotting in an early and late presenting patient. High-sensitivity - cTnT concentrations were 28% higher in the coronary venous system than peripherally (n=71, P<0.001). Coronary venous system samples demonstrated cT n T-I-C complex, free intact cTnT , and 29 kD a and 15 to 18 kD a cTnT fragments, all in higher concentrations than in simultaneously obtained peripheral samples. While cT n T-I-C complex proportionally decreased, and disappeared over time, 15 to 18 kD a cTnT fragments increased. Moreover, cT n T-I-C complex was more prominent in the early than in the late presenting patient. Conclusions This explorative study in non- ST -segment-elevation myocardial infarction shows that cTnT is released from cardiomyocytes as a combination of cT n T-I-C complex, free intact cTnT , and multiple cTnT fragments indicating intracellular cTnT degradation. Over time, the cT n T-I-C complex disappeared because of in vivo degradation. These insights might serve as a stepping stone toward a high-sensitivity- cTnT immunoassay more specific for myocardial infarction.

Brain tissue plasticity: protein synthesis rates of the human brain

All tissues undergo continuous reconditioning via the complex orchestration of changes in tissue protein synthesis and breakdown rates. Skeletal muscle tissue has been well studied in this regard, and has been shown to turnover at a rate of 1-2% per day in vivo in humans. Few data are available on protein synthesis rates of other tissues. Because of obvious limitations with regard to brain tissue sampling no study has ever measured brain protein synthesis rates in vivo in humans. Here, we applied stable isotope methodology to directly assess protein synthesis rates in neocortex and hippocampus tissue of six patients undergoing temporal lobectomy for drug-resistant temporal lobe epilepsy (Clinical trial registration: NTR5147). Protein synthesis rates of neocortex and hippocampus tissue averaged 0.17 ± 0.01 and 0.13 ± 0.01%/h, respectively. Brain tissue protein synthesis rates were 3-4-fold higher than skeletal muscle tissue protein synthesis rates (0.05 ± 0.01%/h; P < 0.001). In conclusion, the protein turnover rate of the human brain is much higher than previously assumed.

Dose-Dependent Increases in Whole-Body Net Protein Balance and Dietary Protein-Derived Amino Acid Incorporation into Myofibrillar Protein During Recovery from Resistance Exercise in Older Men

BACKGROUND

Age-related decline in skeletal muscle mass is at least partly attributed to anabolic resistance to food intake. Resistance exercise sensitizes skeletal muscle tissue to the anabolic properties of amino acids.

OBJECTIVE

The present study assessed protein digestion and amino acid absorption kinetics, whole-body protein balance, and the myofibrillar protein synthetic response to ingestion of different amounts of protein during recovery from resistance exercise in older men.

METHODS

Forty-eight healthy older men [mean ± SEM age: 66 ± 1 y; body mass index (kg/m2): 25.4 ± 0.3] were randomly assigned to ingest 0, 15, 30, or 45 g milk protein concentrate after a single bout of resistance exercise consisting of 4 sets of 10 repetitions of leg press and leg extension and 2 sets of 10 repetitions of lateral pulldown and chest press performed at 75-80% 1-repetition maximum. Postprandial protein digestion and amino acid absorption kinetics, whole-body protein metabolism, and myofibrillar protein synthesis rates were assessed using primed, continuous infusions of l-[ring-2H5]-phenylalanine, l-[ring-2H2]-tyrosine, and l-[1-13C]-leucine combined with ingestion of intrinsically l-[1-13C]-phenylalanine and l-[1-13C]-leucine labeled protein.

RESULTS

Whole-body net protein balance showed a dose-dependent increase after ingestion of 0, 15, 30, or 45 g of protein (0.015 ± 0.002, 0.108 ± 0.004, 0.162 ± 0.008, and 0.215 ± 0.009 μmol Phe · kg-1 · min-1, respectively; P < 0.001). Myofibrillar protein synthesis rates were higher after ingesting 30 (0.0951% ± 0.0062%/h, P = 0.07) or 45 g of protein (0.0970% ± 0.0062%/h, P < 0.05) than after 0 g (0.0746% ± 0.0051%/h). Incorporation of dietary protein-derived amino acids (l-[1-13C]-phenylalanine) into de novo myofibrillar protein showed a dose-dependent increase after ingestion of 15, 30, or 45 g protein (0.0171 ± 0.0017, 0.0296 ± 0.0030, and 0.0397 ± 0.0026 mole percentage excess, respectively; P < 0.05).

CONCLUSIONS

Dietary protein ingested during recovery from resistance exercise is rapidly digested and absorbed. Whole-body net protein balance and dietary protein-derived amino acid incorporation into myofibrillar protein show dose-dependent increases. Ingestion of ≥30 g protein increases postexercise myofibrillar protein synthesis rates in older men. This trial was registered at Nederlands Trial Register as NTR4492.

Mass Spectrometric Identification of Cardiac Troponin T in Urine of Patients Suffering from Acute Myocardial Infarction

BACKGROUND

Because of its high cardiospecificity, cardiac troponin T (cTnT) is one of the first-choice biomarkers to diagnose acute myocardial infarction (AMI). cTnT is extensively fragmented in serum of patients suffering from AMI. However, it is currently unknown whether all cTnT is completely degraded in the body or whether some cTnT fragments can leave the body via urine. The aim of the present study is to develop a method for the detection of cTnT in urine and to examine whether cTnT is detectable in patient urine.

METHODS

Proteins in urine samples of 20 patients were precipitated using a cTnT-specific immunoprecipitation technique and a nonspecific acetonitrile protein precipitation. After in-solution digestion of the precipitated proteins, the resulting peptides were separated and analyzed using HPLC and mass spectrometry with a targeted selected ion monitoring assay with data-dependent tandem mass spectrometry (t-SIM/dd-MS2).

RESULTS

The t-SIM/dd-MS2 assay was validated using a synthetic peptide standard containing 10 specific cTnT peptides of interest and with purified human intact cTnT spiked in urine from healthy individuals. Using this assay, 6 different cTnT-specific peptides were identified in urine samples from 3 different patients, all suffering from AMI.

CONCLUSIONS

We show here for the first time that cTnT can be present in the urine of AMI patients using a targeted LC-MS/MS assay. Whether the presence of cTnT in urine reflects a physiological or pathophysiological process still needs to be elucidated.

Identification and Characterization of Cardiac Troponin T Fragments in Serum of Patients Suffering from Acute Myocardial Infarction

BACKGROUND

Cardiac troponin T (cTnT) is the preferred biomarker for the diagnosis of acute myocardial infarction (AMI). It has been suggested that cTnT is present predominantly in fragmented forms in human serum following AMI. In this study, we have used a targeted mass spectrometry assay and epitope mapping using Western blotting to confirm this hypothesis.

METHODS

cTnT was captured from the serum of 12 patients diagnosed with AMI using an immunoprecipitation technique employing the M11.7 catcher antibody and fractionated with SDS-PAGE. Coomassie-stained bands of 4 patients at 37, 29, and 16 kDa were excised from the gel, digested with trypsin, and analyzed on a Q Exactive instrument set on targeted Selected Ion Monitoring mode with data-dependent tandem mass spectrometry (MS/MS) for identification. Western blotting employing 3 different antibodies was used for epitope mapping.

RESULTS

Ten cTnT peptides of interest were targeted. By using MS/MS, all of these peptides were identified in the 37-kDa, intact, cTnT band. In the 29- and 16-kDa fragment bands, 8 and 4 cTnT-specific peptides were identified, respectively. Some of these peptides were "semitryptic," meaning that their C-termini were not formed by trypsin cleavage. The C-termini of these semitryptic peptides represent the C-terminal end of the cTnT molecules present in these bands. These results were confirmed independently by epitope mapping.

CONCLUSIONS

Using LC-MS, we have succeeded in positively identifying the 29- and 16-kDa fragment bands as cTnT-derived products. The amino acid sequences of the 29- and 16-kDa fragments are Ser79-Trp297 and Ser79-Gln199, respectively.

Increasing Insulin Availability Does Not Augment Postprandial Muscle Protein Synthesis Rates in Healthy Young and Older Men

CONTEXT

Skeletal muscle protein synthesis is highly responsive to food intake. It has been suggested that the postprandial increase in circulating insulin modulates the muscle protein synthetic response to feeding.

OBJECTIVE

The objective of the study was to investigate whether a greater postprandial rise in circulating insulin level increases amino acid uptake in muscle and augments postprandial muscle protein synthesis rates.

PARTICIPANTS AND DESIGN

Forty-eight healthy young (age 22 ± 1 y; body mass index 22.0 ± 0.3 kg/m²) and older males (age 68 ± 1 y; body mass index 26.3 ± 0.4 kg/m²) ingested 20 g intrinsically L-[1-¹³C]-leucine- and L-[1-¹³C]-phenylalanine-labeled casein protein with or without local insulin infusion. Primed continuous infusions of L-[1-¹³C]-leucine and L-[ring-²H₅]-phenylalanine were applied, with arterial and venous blood samples and muscle biopsies being collected during a 5-hour postprandial period.

RESULTS

Insulin administration did not increase overall leg blood flow (P = .509) but increased amino acid uptake over the leg in both young and older subjects (P = .003). The greater amino acid uptake over the leg did not further increase postprandial muscle protein synthesis rates (0.050% ± 0.006% and 0.037% ± 0.004% per hour vs 0.044% ± 0.004% and 0.037% ± 0.002% per hour in the insulin-stimulated vs control condition in the young and older groups, respectively; P = .804) and did not affect postprandial deposition of dietary protein-derived amino acids in de novo muscle protein (P = .872).

CONCLUSION

Greater postprandial plasma insulin availability stimulates amino acid uptake over the leg but does not further augment postprandial muscle protein synthesis rates or stimulate the postprandial deposition of protein derived amino acids into de novo muscle protein in healthy young and older men.

Validation, optimisation, and application data in support of the development of a targeted selected ion monitoring assay for degraded cardiac troponin T

Cardiac troponin T (cTnT) fragmentation in human serum was investigated using a newly developed targeted selected ion monitoring assay, as described in the accompanying article: “Development of a targeted selected ion monitoring assay for the elucidation of protease induced structural changes in cardiac troponin T” [1]. This article presents data describing aspects of the validation and optimisation of this assay. The data consists of several figures, an excel file containing the results of a sequence identity search, and a description of the raw mass spectrometry (MS) data files, deposited in the ProteomeXchange repository with id PRIDE: PXD003187.

Ascorbic acid serum levels are reduced in patients with hematological malignancies

In this paper we demonstrate that patients treated with chemotherapy and/or hematopoietic stem cell transplantation (HSCT) have highly significant reduced serum ascorbic acid (AA) levels compared to healthy controls. We recently observed in in vitro experiments that growth of both T and NK cells from hematopoietic stem cells is positively influenced by AA. It might be of clinical relevance to study the function and recovery of immune cells after intensive treatment, its correlation to AA serum levels and the possible effect of AA supplementation.

Post-Prandial Protein Handling: You Are What You Just Ate

Background

Protein turnover in skeletal muscle tissue is highly responsive to nutrient intake in healthy adults.

Objective

To provide a comprehensive overview of post-prandial protein handling, ranging from dietary protein digestion and amino acid absorption, the uptake of dietary protein derived amino acids over the leg, the post-prandial stimulation of muscle protein synthesis rates, to the incorporation of dietary protein derived amino acids in de novo muscle protein.

Design

12 healthy young males ingested 20 g intrinsically [1-¹³C]-phenylalanine labeled protein. In addition, primed continuous L-[ring-²H₅]-phenylalanine, L-[ring-²H₂]-tyrosine, and L-[1-¹³C]-leucine infusions were applied, with frequent collection of arterial and venous blood samples, and muscle biopsies throughout a 5 h post-prandial period. Dietary protein digestion, amino acid absorption, splanchnic amino acid extraction, amino acid uptake over the leg, and subsequent muscle protein synthesis were measured within a single in vivo human experiment.

Results

55.3±2.7% of the protein-derived phenylalanine was released in the circulation during the 5 h post-prandial period. The post-prandial rise in plasma essential amino acid availability improved leg muscle protein balance (from -291±72 to 103±66 μM·min^-1·100 mL leg volume^-1; P<0.001). Muscle protein synthesis rates increased significantly following protein ingestion (0.029±0.002 vs 0.044±0.004%·h^-1 based upon the muscle protein bound L-[ring-²H₅]-phenylalanine enrichments (P<0.01)), with substantial incorporation of dietary protein derived L-[1-¹³C]-phenylalanine into de novo muscle protein (from 0 to 0.0201±0.0025 MPE).

Conclusion

Ingestion of a single meal-like amount of protein allows ~55% of the protein derived amino acids to become available in the circulation, thereby improving whole-body and leg protein balance. About 20% of the dietary protein derived amino acids released in the circulation are taken up in skeletal muscle tissue following protein ingestion, thereby stimulating muscle protein synthesis rates and providing precursors for de novo muscle protein synthesis.

Trial Registration

trialregister.nl 3638

Integrating multiple omics to unravel mechanisms of Cyclosporin A induced hepatotoxicity in vitro

In order to improve attrition rates of candidate-drugs there is a need for a better understanding of the mechanisms underlying drug-induced hepatotoxicity. We aim to further unravel the toxicological response of hepatocytes to a prototypical cholestatic compound by integrating transcriptomic and metabonomic profiling of HepG2 cells exposed to Cyclosporin A. Cyclosporin A exposure induced intracellular cholesterol accumulation and diminished intracellular bile acid levels. Performing pathway analyses of significant mRNAs and metabolites separately and integrated, resulted in more relevant pathways for the latter. Integrated analyses showed pathways involved in cell cycle and cellular metabolism to be significantly changed. Moreover, pathways involved in protein processing of the endoplasmic reticulum, bile acid biosynthesis and cholesterol metabolism were significantly affected. Our findings indicate that an integrated approach combining metabonomics and transcriptomics data derived from representative in vitro models, with bioinformatics can improve our understanding of the mechanisms of action underlying drug-induced hepatotoxicity. Furthermore, we showed that integrating multiple omics and thereby analyzing genes, microRNAs and metabolites of the opposed model for drug-induced cholestasis can give valuable information about mechanisms of drug-induced cholestasis in vitro and therefore could be used in toxicity screening of new drug candidates at an early stage of drug discovery.

Integrative cross-omics analysis in primary mouse hepatocytes unravels mechanisms of cyclosporin A-induced hepatotoxicity

The liver is responsible for drug metabolism and drug-induced hepatotoxicity is the most frequent reason for drug withdrawal, indicating that better pre-clinical toxicity tests are needed. In order to bypass animal models for toxicity screening, we exposed primary mouse hepatocytes for exploring the prototypical hepatotoxicant cyclosporin A. To elucidate the mechanisms underlying cyclosporin A-induced hepatotoxicity, we analyzed expression levels of proteins, mRNAs, microRNAs and metabolites. Integrative analysis of transcriptomics and proteomics showed that protein disulfide isomerase family A, member 4 was up-regulated on both the protein level and mRNA level. This protein is involved in protein folding and secretion in the endoplasmic reticulum. Furthermore, the microRNA mmu-miR-182-5p which is predicted to interact with the mRNA of this protein, was also differentially expressed, further emphasizing endoplasmic reticulum stress as important event in drug-induced toxicity. To further investigate the interaction between the significantly expressed proteins, a network was created including genes and microRNAs known to interact with these proteins and this network was used to visualize the experimental data. In total 6 clusters could be distinguished which appeared to be involved in several toxicity related processes, including alteration of protein folding and secretion in the endoplasmic reticulum. Metabonomic analyses resulted in 5 differentially expressed metabolites, indicative of an altered glucose, lipid and cholesterol homeostasis which can be related to cholestasis. Single and integrative analyses of transcriptomics, proteomics and metabonomics reveal mechanisms underlying cyclosporin A-induced cholestasis demonstrating that endoplasmic reticulum stress and the unfolded protein response are important processes in drug-induced liver toxicity.

Critical appraisal of 13C breath tests for microsomal liver function: aminopyrine revisited

As liver diseases are a major health problem and especially the incidence of metabolic liver diseases like non-alcoholic fatty liver disease (NAFLD) is rising, the demand for non-invasive tests is growing to replace liver biopsy. Non-invasive tests such as carbon-labelled breath tests can provide a valuable contribution to the evaluation of metabolic liver function. This review aims to critically appraise the value of the (13) C-labelled microsomal breath tests for the evaluation of metabolic liver function, and to discuss the role of cytochrome P450 enzymes in the metabolism of the different probe drugs, especially of aminopyrine. Although a number of different probe drugs have been used in breath tests, the perfect drug to assess the functional metabolic capacity of the liver has not been found. Data suggest that both the (13) C(2) -aminopyrine and the (13) C-methacetin breath test can play a role in assessing the capacity of the microsomal liver function and may be useful in the follow-up of patients with chronic liver diseases. Furthermore, CYP2C19 seems to be an important enzyme in the N-demethylation of aminopyrine, and polymorphisms in this gene may influence breath test values, which should be kept in mind when performing the (13) C(2) -aminopyrine breath test in clinical practice.

Cardiac troponin in ischemic cardiomyocytes: intracellular decrease before onset of cell death

AIM

Cardiac troponin I (cTnI) and T (cTnT) are the most important biomarkers in the diagnosis of acute myocardial infarction (AMI). Nevertheless, they can be elevated in the absence of AMI. It is unclear if such elevations represent irreversible cardiomyocyte-damage or leakage from viable cardiomyocytes. Our objective is to evaluate whether cTn is released from viable cardiomyocytes in response to ischemia and to identify differences in the release of cTn and its molecular forms.

METHODS AND RESULTS

HL-1 cardiomyocytes (mouse) were subjected to ischemia (modeled by anoxia with glucose deprivation). The total contents and molecular forms of cTn were determined in culture media and cell lysates. Cell viability was assessed from the release of lactate dehydrogenase (LDH). Before the release of LDH, the intracellular cTn content in ischemic cells decreased significantly compared to control (52% for cTnI; 23% for cTnT) and was not matched by a cTn increase in the medium. cTnI decreased more rapidly than cTnT, resulting in an intracellular cTnT/cTnI ratio of 25.5 after 24 h of ischemia. Western blots revealed changes in the relative amounts of fragmented cTnI and cTnT in ischemic cells.

CONCLUSIONS

HL-1 cardiomyocytes subjected to simulated ischemia released cTnI and cTnT only in combination with the release of LDH. We find no evidence of cTn release from viable cardiomyocytes, but did observe a significant decrease in cTn content, before the onset of cell death. Intracellular decrease of cTn in viable cardiomyocytes can have important consequences for the interpretation of cTn values in clinical practice.

Characterization of the perfusate proteome of human donor kidneys

BACKGROUND

Preservation of deceased donor kidneys by hypothermic machine perfusion results in superior transplant outcomes as compared with static cold storage and provides the opportunity to measure biomarkers of cellular injury in perfusate samples. Identification of biomarkers predicting early graft dysfunction so far has met with limited success.

METHODS

Two-dimensional difference gel electrophoresis and mass spectrometry were used to explore the proteome of perfusate samples from machine-perfused human donor kidneys (N = 18) and to discover novel biomarkers of ischaemic acute kidney injury.

RESULTS

Thirty-two protein spots were successfully identified, representing 19 unique proteins that were derived from renal tissue and from residual plasma in the renal microcirculation. Two unidentified protein spots were significantly up-regulated, whereas one protein spot--identified as haptoglobin--was significantly down-regulated in the perfusate of ischaemically injured kidneys from donors after cardiac death as compared with kidneys from brain-dead donors who had not suffered warm ischaemic injury. Furthermore, two protein spots were up-regulated in kidneys that never functioned after transplantation, whereas one spot was up-regulated--identified as α1-antitrypsin--in kidneys with delayed graft function.

CONCLUSIONS

We provide the first description of the renal perfusate proteome and present preliminary evidence of differentially expressed biomarkers in human donor kidneys with different levels of acute ischaemic injury. Their diagnostic value for the selection of marginal kidneys in clinical transplantation should be determined in future studies.

Prediction of asthma exacerbations in children: results of a one-year prospective study

BACKGROUND

Underdiagnosis and low levels of asthma control are frequent occurring problems in patients with asthma.

OBJECTIVE

The study aim was to evaluate the ability of non-invasive inflammatory markers in exhaled breath to predict exacerbations of childhood asthma, and to assess the time course of changes in these exhaled markers before, during and after exacerbations.

METHODS

The design was a prospective one-year longitudinal study. Regular two-month visits at the outpatient clinic were performed. Forty children with asthma (aged 6-16 years) participated. The primary outcome measure was the occurrence of an exacerbation. Assessment was made of the presence and severity of pulmonary symptoms, use of medication, and measurements of forced expiratory volume in 1 s using home monitor. The following independent parameters were assessed during outpatient visits: (1) exhaled nitric oxide, (2) inflammatory markers in exhaled breath condensate: acidity, nitrite, hydrogen peroxide, interleukin-1α, -5, -13, interferon-γ, (3) lung function, (4) asthma control score.

RESULTS

Thirty-eight of 40 children completed the study. Sixteen children developed exacerbations, of which ten were moderate and six severe. Univariate Cox regression analysis revealed that condensate acidity, interleukin-5 and asthma control score were significant predictors of an asthma exacerbation (P < 0.05). In the multivariate Cox regression analysis, exacerbations were best predicted by the asthma control score and by the level of interleukin-5 in exhaled breath condensate (Wald scores of 7.19 and 4.44, P = 0.007 and P = 0.035 respectively). The predicted survival curve of this multivariate model showed a two times reduced risk on exacerbations in the category of children with the 10% most optimal values of IL-5 and asthma control score.

CONCLUSIONS AND CLINICAL RELEVANCE

Both exhaled breath condensate interleukin-5 level and asthma control score were significant predictors of asthma exacerbations. These findings open up the possibility of assessing the potential of such parameters to titrate asthma treatment in future studies.

Differential protein expression in serum of abdominal aortic aneurysm patients - a proteomic approach

OBJECTIVE

The aim of the study is to investigate the differential expression of proteins in serum of abdominal aortic aneurysm (AAA) patients in relation to aneurysm size (D(max)) and progression.

METHODS

Two-dimensional differential in-gel electrophoresis (2D-DIGE) together with tandem mass spectrometry (MS/MS) was used to analyse the serum proteome from patients with small (D(max) 30-54 mm) AAA, either stable (increase D(max) <5 mm year⁻¹; n = 8) or progressive (increase D(max) ≥5 mm year⁻¹; n = 8), and large (D(max) ≥ 55 mm; n = 8) AAA. The identified proteins were quantitatively validated in a larger population (n = 80).

RESULTS

Several proteins were differentially expressed in serum of small stable, small progressive and large AAA. Three validated proteins (immunoglobulin G (IgG), α1-antitrypsin (α1-AT) and Factor XII activity) showed strong correlation with D(max). Size combined with either Factor XII activity or α1-antitrypsin had minimal effect on the prognostic value in predicting aneurysm progression compared with size alone (area under the curve (AUC), 0.85; 95% confidence interval (CI), 0.73-0.97; p < 0.001 and AUC, 0.85; 95% CI, 0.72-0.98; p < 0.001 vs. AUC, 0.83; 95% CI, 0.71-0.96; p < 0.001, respectively).

CONCLUSION

The present study indicates that both Factor XII and α1-antitrypsin are found in increased amounts in the serum of patients with expanding AAA. However, combination of either Factor XII or α1-antitrypsin with aneurysm diameter had little effect on prediction of aneurysm progression versus diameter alone.

Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men

The loss of muscle mass with aging has been, at least partly, attributed to a blunted muscle protein synthetic response to food intake. Leucine coingestion has been reported to stimulate postprandial insulin release and augment postprandial muscle protein accretion. We assessed the clinical benefits of 6 mo of leucine supplementation in elderly, type 2 diabetes patients. Sixty elderly males with type 2 diabetes (age, 71 ± 1 y; BMI, 27.3 ± 0.4 kg/m(2)) were administered 2.5 g L-leucine (n = 30) or a placebo (n = 30) with each main meal during 6 mo of nutritional intervention (7.5 g/d leucine or placebo). Body composition, muscle fiber characteristics, muscle strength, glucose homeostasis, and basal plasma amino acid and lipid concentrations were assessed prior to, during, and after intervention. Lean tissue mass did not change or differ between groups and at 0, 3, and 6 mo were 61.9 ± 1.1, 62.2 ± 1.1, and 62.0 ± 1.0 kg, respectively, in the leucine group and 62.2 ± 1.3, 62.2 ± 1.3, and 62.2 ± 1.3 kg in the placebo group. There also were no changes in body fat percentage, muscle strength, and muscle fiber type characteristics. Blood glycosylated hemoglobin did not change or differ between groups and was 7.1 ± 0.1% in the leucine group and 7.2 ± 0.2% in the placebo group. Consistent with this, oral glucose insulin sensitivity and plasma lipid concentrations did not change or differ between groups. We conclude that prolonged leucine supplementation (7.5 g/d) does not modulate body composition, muscle mass, strength, glycemic control, and/or lipidemia in elderly, type 2 diabetes patients who habitually consume adequate dietary protein.

FSH isoform pattern in classic galactosemia

Female classic galactosemia patients suffer from primary ovarian insufficiency (POI). The cause for this long-term complication is not fully understood. One of the proposed mechanisms is that hypoglycosylation of complex molecules, a known secondary phenomenon of galactosemia, leads to FSH dysfunction. An earlier study showed less acidic isoforms of FSH in serum samples of two classic galactosemia patients compared to controls, indicating hypoglycosylation. In this study, FSH isoform patterns of five classic galactosemia patients with POI were compared to the pattern obtained in two patients with a primary glycosylation disorder (phosphomannomutase-2-deficient congenital disorders of glycosylation, PMM2-CDG) and POI, and in five postmenopausal women as controls. We used FPLC chromatofocussing with measurement of FSH concentration per fraction, and discovered that there were no significant differences between galactosemia patients, PMM2-CDG patients and postmenopausal controls. Our results do not support that FSH dysfunction due to a less acidic isoform pattern because of hypoglycosylation is a key mechanism of POI in this disease.

Gonadal function in male and female patients with classic galactosemia

BACKGROUND

Hypergonadotropic hypoestrogenic infertility is the most burdensome complication for females suffering from classic galactosemia. In contrast, male gonadal function seems less affected. The underlying mechanism is not understood and several pathogenic mechanisms have been proposed. Timing of the lesion, prenatal or chronic post-natal, or a combination of both are not yet clear.

METHODS

This review focuses on gonadal function in males and females, ovarian imaging and histology in this disease. It is based on the literature known to the authors and a Pubmed search using the keywords galactosemia, GALT deficiency, (premature) ovarian failure/insufficiency/dysfunction, testicular function, gonadotrophins, FSH, LH (published between January 1971 and April 2009).

RESULTS

Male gonads are less affected, boys spontaneously reach puberty, although onset can be delayed. Semen quality has not been extensively studied. Several affected males are known to have fathered a child. Female gonads are invariably affected, although to a varied extent (hypergonadotropic hypoestrogenic ovarian dysfunction). Intriguingly, FSH is often already increased in infancy. Imaging usually shows hypoplastic and streak-like ovaries. Histological findings in some cases reveal the presence of morphologically normal but decreased numbers of primordial follicles, with the absence of intermediate and Graafian follicles.

CONCLUSION

Gonads in males seem less affected than in females who exhibit hypergonadotropic hypoestrogenic subfertility. FSH can be elevated in infancy, and ovarian histology sometimes shows the presence of normal primordial follicles with absence of intermediate and Graafian follicles. These findings are similar to other genetic diseases primarily affecting the ovary.

Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men

BACKGROUND

It has been reported that the blunted muscle protein synthetic response to food intake in the elderly can be normalized by increasing the leucine content of a meal.

OBJECTIVE

The objective was to assess the effect of 3 mo of leucine supplementation on muscle mass and strength in healthy elderly men.

DESIGN

Thirty healthy elderly men with a mean (+/-SEM) age of 71 +/- 4 y and body mass index (BMI; in kg/m(2)) of 26.1 +/- 0.5 were randomly assigned to either a placebo-supplemented (n = 15) or leucine-supplemented (n = 15) group. Leucine or placebo (2.5 g) was administered with each main meal during a 3-mo intervention period. Whole-body insulin sensitivity, muscle strength (one-repetition maximum), muscle mass (measured by computed tomography and dual-energy X-ray absorptiometry), myosin heavy chain isoform distribution, and plasma amino acid and lipid profiles were assessed before, during, and/or after the intervention period.

RESULTS

No changes in skeletal muscle mass or strength were observed over time in either the leucine- or placebo-supplemented group. No improvements in indexes of whole-body insulin sensitivity (oral glucose insulin sensitivity index and the homeostasis model assessment of insulin resistance), blood glycated hemoglobin content, or the plasma lipid profile were observed.

CONCLUSION

Long-term leucine supplementation (7.5 g/d) does not augment skeletal muscle mass or strength and does not improve glycemic control or the blood lipid profile in healthy elderly men. This trial was registered at clinicaltrials.gov as NCT00807508.

A SELDI-TOF-MS study in Lacunar Stroke with Subsequent Haptoglobin Phenotyping

Using Surface-Enhanced Laser Desorption / Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS), we aimed to detect differences in protein profile in serum samples of two lacunar stroke subtypes. SELDI-TOF-MS, followed by protein identification, was performed in samples of 8 first-ever lacunar stroke patients with MR imaging showing a single symptomatic lacunar lesion (type 1), and 8 with multiple additional "silent" lacunar lesions and extensive white matter lesions (type 2). A 16 kDa protein, identified as alpha-2-chain of haptoglobin (Hp), was found to be overrepresented in type 1 compared to type 2 (peak intensity 12.5 vs. 5.0; p=0.02). As a polymorphism with two alleles, Hp-1 and Hp 2, determines the presence of alpha-1 and/or alpha-2-chains in the Hp-molecule, Hp phenotypic analysis was performed. Hp 1 : Hp-2 allele frequency was 0.562 : 0.438 in type 1 and 0.812 : 0.188 in type 2 (population reference approximately 0.4 : 0.6). We conclude that the overrepresentation of the alpha-2-chain in lacunar stroke type 1 compared to type 2 relates to a higher Hp-2 allele frequency in the former. Yet, compared to population reference, the phenotype distribution in both patient groups deviates towards a high Hp-1 allele frequency. Our findings suggest a role for the Hp gene in the etiology of cerebral small vessel disease. Larger studies are now needed to explore this new candidate gene.

Protein supplementation before and after exercise does not further augment skeletal muscle hypertrophy after resistance training in elderly men

BACKGROUND

Considerable discrepancy exists in the literature on the proposed benefits of protein supplementation on the adaptive response of skeletal muscle to resistance-type exercise training in the elderly.

OBJECTIVE

The objective was to assess the benefits of timed protein supplementation on the increase in muscle mass and strength during prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein.

DESIGN

Healthy elderly men (n = 26) aged 72 +/- 2 y were randomly assigned to a progressive, 12-wk resistance-type exercise training program with (protein group) or without (placebo group) protein provided before and immediately after each exercise session (3 sessions/wk, 20 g protein/session). One-repetition maximum (1RM) tests were performed regularly to ensure a progressive workload during the intervention. Muscle hypertrophy was assessed at the whole-body (dual-energy X-ray absorptiometry), limb (computed tomography), and muscle fiber (biopsy) level.

RESULTS

The 1RM strength increased approximately 25-35% in both groups (P < 0.001). Dual-energy X-ray absorptiometry and computed tomography scans showed similar increases in leg muscle mass (6 +/- 1% in both groups; P < 0.001) and in the quadriceps (9 +/- 1% in both groups), from 75.9 +/- 3.7 and 73.8 +/- 3.2 to 82.4 +/- 3.9 and 80.0 +/- 3.0 cm2 in the placebo and protein groups, respectively (P < 0.001). Muscle fiber hypertrophy was greater in type II (placebo: 28 +/- 6%; protein: 29 +/- 4%) than in type I (placebo: 5 +/- 4%; protein: 13 +/- 6%) fibers, but the difference between groups was not significant.

CONCLUSION

Timed protein supplementation immediately before and after exercise does not further augment the increase in skeletal muscle mass and strength after prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein. This trial was registered at clinicaltrials.gov as NCT00744094.

Biomarkers in exhaled breath condensate indicate presence and severity of cystic fibrosis in children

Chronic airway inflammation is present in cystic fibrosis (CF). Non-invasive inflammometry may be useful in disease management. The aim of the present cross-sectional study was to investigate: (i) the ability of fractional exhaled nitric oxide and inflammatory markers (IM) [exhaled breath condensate (EBC) acidity, nitrite, nitrate, hydrogen peroxide (H(2)O(2)), 8-isoprostane, Th1/Th2 cytokines] to indicate (exacerbations of) CF; and (ii) the ability of these non-invasive IM to indicate CF disease severity. In 98 children (48 CF/50 controls), exhaled nitric oxide was measured using the NIOX, and condensate was collected using a glass condenser. In CF interferon (IFN-gamma) and nitrite concentrations were significantly higher, whereas exhaled nitric oxide levels were significantly lower compared with controls (3.3 +/- 0.3 pg/ml, 2.2 +/- 0.2 microM, 10.0 +/- 1.2 p.p.b. vs. 2.6 +/- 0.2 pg/ml, 1.4 +/- 0.1 microM, 15.4 +/- 1.4 p.p.b. respectively). Using multivariate logistic regression models, the presence of CF was best indicated by 8-isoprostane, nitrite and IFN-gamma [sensitivity 78%, specificity 83%; area under receiver operating characteristic curve (AUC) 0.906, p < 0.001]. An exacerbation of CF was best indicated by 8-isoprostane and nitrite (sensitivity 40%, specificity 97%, AUC curve 0.838, p = 0.009). Most indicative biomarkers of CF severity were exhaled nitric oxide, and condensate acidity (sensitivity 96%, specificity 67%; AUC curve 0.751, p = 0.008). In this cross-sectional study, the combination of different exhaled IM could indicate (exacerbations of) CF, and severity of the disease in children. Longitudinal data are necessary to further confirm the role of these markers for the management of CF in children.

Comparison of the anti-inflammatory effects of extra-fine hydrofluoroalkane-beclomethasone vs fluticasone dry powder inhaler on exhaled inflammatory markers in childhood asthma

BACKGROUND

Extra-fine hydrofluoroalkane-beclomethasone differs from other inhaled corticosteroids by its fine aerosol characteristics. Therefore, extra-fine hydrofluoroalkane-beclomethasone may be particularly useful for treating peripheral airway inflammation in asthma.

OBJECTIVE

To analyze the anti-inflammatory effects of extra-fine hydrofluoroalkane-beclomethasone vs fluticasone dry powder inhaler (DPI) in asthmatic children by measuring bronchial and alveolar nitric oxide (NO) and inflammatory markers in exhaled breath condensate (EBC).

METHODS

In a 6-month crossover study, 33 children aged 6 to 12 years with moderate persistent asthma were randomly treated with extra-fine hydrofluoroalkane-beclomethasone (200 microg daily via an Autohaler) and fluticasone DPI (200 microg daily via a Diskus). The primary outcome variables were alveolar NO concentration and bronchial NO flux. The secondary outcome variables were levels of inflammatory markers in EBC, lung function indices, symptoms, exacerbations, and adverse effects. All the variables were recorded at baseline and after each treatment period.

RESULTS

Mean +/- SE alveolar NO concentration and bronchial NO flux were comparable after treatment with hydrofluoroalkane-beclomethasone vs fluticasone DPI (4.7 +/- 0.5 vs 4.3 +/- 0.5 ppb, P = .55, and 1,124.3 +/- 253.6 vs 1,029.1 +/- 195.5 pL/s, P = .70, respectively). In addition, levels of inflammatory markers in EBC, lung function indices, and symptoms did not differ between treatments. Patients used fewer beta2-agonists during the last 2 weeks of hydrofluoroalkane-beclomethasone treatment.

CONCLUSION

The anti-inflammatory effects of hydrofluoroalkane-beclomethasone are similar to those of fluticasone DPI in children with moderate persistent asthma.

Exhaled nitric oxide and biomarkers in exhaled breath condensate indicate the presence, severity and control of childhood asthma

BACKGROUND

Exhaled nitric oxide and inflammatory biomarkers in exhaled breath condensate may be useful to diagnose and monitor childhood asthma. Their ability to indicate an asthma diagnosis, and to assess asthma severity and control, is largely unknown.

OBJECTIVE

To study (1) the ability of exhaled nitric oxide and inflammatory markers in exhaled breath condensate (nitrite, nitrate, hydrogen peroxide, 8-isoprostane, IFN-gamma, TNF-alpha, IL-2, -4, -5, -10 and acidity) to discriminate between childhood asthma and controls. (2) The ability of these biomarkers to indicate asthma severity and control.

METHODS

One-hundred and fourteen children were included: 64 asthmatics (10.7+/-3.0 years, 67.2% atopic) and 50 controls (10.0+/-0.4 years). Condensate was collected using a glass condenser.

RESULTS

Exhaled nitric oxide, IFN-gamma and IL-4 in exhaled breath condensate differed significantly between asthma and controls. Multivariate backward logistic regression models demonstrated that IL-4 (odds ratio 7.9, 95% confidence interval 1.2-51.0) was the only significant indicator of an asthma diagnosis. Asthma control was best assessed by exhaled nitric oxide, 8-isoprostane, IFN-gamma and IL-4 (sensitivity 82%, specificity 80%, P<0.05), whereas exhaled nitric oxide, 8-isoprostane, nitrate and nitrite in condensate were the best indicators of asthma severity (sensitivity 89%, specificity 72%, P<0.05).

CONCLUSION

Different markers in condensate are of an additional value to exhaled nitric oxide, and are needed in non-invasive inflammometry. They could be useful to diagnose asthma and to indicate asthma control and severity in childhood.

A specific immunoprecipitation method for isolating isoforms of insulin-like growth factor binding protein-3 from serum

BACKGROUND

This report describes an in-house developed immunoprecipitation method to isolate insulin-like growth factor binding protein-3 (IGFBP-3) and its isoforms from serum. The method was compared to other existing immunoprecipitation methods. The study of IGFBP-3 isoforms is relevant for further studies on congenital defects in glycosylation (CDG), galactosemia, and alcoholic liver cirrhosis.

METHODS

Monoclonal and/or polyclonal anti-human IGFBP-3 antibodies were covalently immobilised on protein-A Sepharose beads using dimethyl pimelimidate as cross-linker. By incubation with these immobilised antibodies, intact IGFBP-3 and fragments of IGFBP-3 were isolated from serum. Enzyme-linked immunosorbent assay (ELISA) and one-dimensional gel electrophoresis (1-DE) experiments were performed to define the optimal immunoprecipitation method. Isolated proteins were separated by 1-DE and two-dimensional gel electrophoresis (2-DE) and visualised by Western blotting.

RESULTS

ELISA and 1-DE results illustrated that an optimal isolation was performed using PBS for the incubation with serum. Laemmli sample buffer, containing 2-amino-2-(hydroxymethyl)-1,3-propanediol hydrochloride and sodium dodecyl sulfate, or urea/CHAPS was optimal for the elution. Clinical validation was performed using CDG-Ia serum samples. The 2-DE experiments showed characteristic isoform patterns for CDG-Ia.

CONCLUSIONS

The optimized in-house developed immunoprecipitation method resulted in specific detection of IGFBP-3 isoforms and is suitable for further studies on glycosylation defects.

Investigation of release and degradation of cardiac troponin T in patients with acute myocardial infarction

OBJECTIVES

Cardiac troponin T (cTnT) degradation after tissue release is still under debate. Because degradation of cTnT might have consequences on clearance of the molecule from the circulation, but also on the assay performance, the aim of this study was to investigate cTnT release and degradation in serum of AMI patients.

DESIGN AND METHODS

Serum samples were collected from 20 patients with AMI diagnosis undergoing rapid revascularization. Intact cTnT and fragments were detected using a combination of immunoprecipitation, SDS-PAGE and Western blotting.

RESULTS

The intact cTnT protein was detected only during the first 12 h after the cTnT concentration started to increase above the AMI cut-off value of 0.03 microg/L. Thereafter only fragments with molecular weights ranging from 10 to 30 kDa were detected, with two fragments being most prominent (15 and 25 kDa).

CONCLUSIONS

Intact cTnT rapidly disappears from the circulation during the early hours after AMI, but immunoreactive fragments remain present longer. The current cTnT immunoassay detects both intact cTnT and fragments.

SGA and measures for muscle mass and strength in surgical Vietnamese patients

OBJECTIVE

This study compared the outcome of the Subjective Global Assessment (SGA) in preoperative surgical patients with objective measurements of muscle mass and strength and with biochemical data. A secondary aim was to test the influence of inflammatory activity on muscle strength.

METHODS

Two hundred seventy-four consecutive patients who were admitted for elective major abdominal surgery were assessed using the SGA, anthropometry, muscle strength, and laboratory measurements (hemoglobin, protein, albumin, C-reactive protein, and lymphocytes). Normal values for midarm muscle circumference (MAMC) and handgrip strength were obtained in a healthy control group. For all other variables, normal values available for the Vietnamese population were used.

RESULTS

Of 274 patients (151 men, 123 women) assessed, 61 (22.3%) were classified as SGA class A (well nourished), 97 patients (35.4%) as class B (moderately malnourished), and 116 patients (42.3%) as class C (severely malnourished). There were significant differences in age, body weight, percentage of weight loss, triceps skinfold thickness, MAMC, and serum albumin across the three SGA classes. Almost all patients rated class A had normal MAMC and handgrip strength. However, a large proportion of patients rated as B or C also had normal MAMC and handgrip strength (38% of men, 50% of women). Handgrip strength per square meter correlated with serum albumin (r = 0.278, P < 0.001) and this correlation persisted when handgrip strength was controlled for MAMC (r = 0.296, P < 0.001 in men; r = 0.237, P < 0.01 in women).

CONCLUSION

The SGA correctly identifies patients with normal muscle mass and strength but a substantial number of patients rated SGA B or C have normal muscle mass and strength. Muscle strength is not only positively associated with muscle mass but also negatively with inflammatory activity.

Temporal patterns of electrical remodeling in canine ventricular hypertrophy: Focus on IKs downregulation and blunted β-adrenergic activation

OBJECTIVES

Electrical remodeling in cardiac hypertrophy often involves the downregulation of K+ currents, including beta-adrenergic (beta-A)-sensitive IKs. Temporal patterns of ion-channel downregulation are poorly resolved. In dogs with complete atrioventricular block (AVB), we examined (1) the time course of molecular alterations underlying IKs downregulation from acute to chronic hypertrophy; and (2) concomitant changing responses of repolarization to beta-adrenergic receptor (beta-AR) stimulation.

METHODS AND RESULTS

Serial left-ventricular (LV) biopsies were collected from anesthetized dogs during sinus rhythm (SR; control) and at 3, 7 and 30 days of AVB. KCNQ1 mRNA and protein decreased within 3 days (protein expression 58 +/- 10% of control), remaining low thereafter. beta1-AR mRNA and protein decreased more gradually to 53 +/- 8% at 7 days. In chronic-AVB LV myocytes, IKs -tail density was reduced: 1.4 +/- 0.3 pA/pF versus 2.6 +/- 0.4 pA/pF in controls. beta-A enhancement of IKs was reduced. Isoproterenol shortened action-potential duration in control cells, while causing heterogeneous repolarization responses in chronic AVB. beta-A early afterdepolarizations were induced in 4 of 13 chronic-AVB cells, but not in controls. In intact conscious dogs, isoproterenol shortened QTc at SR (by -8 +/- 3% from 295 ms), left it unaltered at 3 days AVB (+1 +/- 3% from 325 ms) and prolonged QTc at 30 days (+6 +/- 3% from 365 ms).

CONCLUSIONS

Profound decrease of KCNQ1 occurs within days after AVB induction and is followed by a more gradual decrease of beta1-AR expression. Downregulation and blunted beta-A activation of IKs contribute to the loss of beta-A-induced shortening of ventricular repolarization, favoring proarrhythmia. Provocation testing with isoproterenol identifies repolarization instability based on acquired channelopathy.

ACE I/D-corrected Z-scores to identify normal and elevated ACE activity in sarcoidosis

BACKGROUND

The value of elevated serum angiotensin-converting enzyme (ACE) activity in the diagnosis and follow-up in sarcoidosis is a matter of ongoing debate. This may be at least related to the insertion (I)/deletion (D) polymorphism in the ACE gene (ACE I/D). ACE activity is influenced by the ACE I/D polymorphism. As a consequence, the use of one reference interval instead of three genotype-specific reference intervals for ACE activity may lead to a less precise interpretation of ACE activity.

METHODS

In order to assess whether determination of ACE activity indeed requires the ACE I/D genotype to be taken into account, we established ACE I/D-corrected reference intervals in healthy, Caucasian volunteers (n=200). In addition, ACE activities in ACE I/D genotyped patients suspected of or having sarcoidosis (n=129) were expressed as the Z-score related to ACE I/D-corrected reference intervals.

RESULTS

Comparison of the Z-score with ACE activity in which ACE I/D is ignored rendered 8.5% misclassification of 'elevated' versus 'normal' ACE or vice versa.

CONCLUSIONS

Our data demonstrate a convenient way to circumvent the use of three reference intervals by introducing a Z-score for ACE activity. It also illustrates the need to re-investigating the possible clinical value of serum ACE activity in sarcoidosis by considering ACE I/D.

Standardization of calibration and quality control using surface enhanced laser desorption ionization-time of flight-mass spectrometry

BACKGROUND

Protein profiling by surface enhanced laser desorption ionization-time of flight-mass spectrometry (SELDI-TOF-MS) is gaining importance as a diagnostic tool for a whole range of diseases. This report describes a QC procedure, which acts prospectively by checking the calibration before starting profiling experiments.

METHODS

A well-defined protocol for calibration of the Protein Biosystem IIc instrument was established, using a commercial QC sample containing independent certified standards and by determination of acceptance criteria. Instrument calibration was performed externally every week with the standards provided by the manufacturer. QC was performed for the period of 5 months.

RESULTS

According to the acceptance criteria defined in this study, data points should be in the established range of the process mean+/-2 standard deviations for the mass-to-charge ratios (m/z values), peak intensities, signal-to-noise ratios (S/N), and peak resolutions for insulin and apomyoglobin in the QC sample. Moreover, it was demonstrated that the pipetting variability in the handling of the QC sample significantly contributed to systematic errors and that spotting of a larger volume of QC sample resulted in a better reproducibility.

CONCLUSIONS

Stringent quality control of the calibration part of SELDI-TOF-MS experiments prevents unreliable data acquisition from the very start.

Cinnamon supplementation does not improve glycemic control in postmenopausal type 2 diabetes patients

In vitro and in vivo animal studies have reported strong insulin-like or insulin-potentiating effects after cinnamon administration. Recently, a human intervention study showed that cinnamon supplementation (1 g/d) strongly reduced fasting blood glucose concentration (30%) and improved the blood lipid profile in patients with type 2 diabetes. The objective of this study was to investigate the effects of cinnamon supplementation on insulin sensitivity and/or glucose tolerance and blood lipid profile in patients with type 2 diabetes. Therefore, a total of 25 postmenopausal patients with type 2 diabetes (aged 62.9 +/- 1.5 y, BMI 30.4 +/- 0.9 kg/m2) participated in a 6-wk intervention during which they were supplemented with either cinnamon (Cinnamomum cassia, 1.5 g/d) or a placebo. Before and after 2 and 6 wk of supplementation, arterialized blood samples were obtained and oral glucose tolerance tests were performed. Blood lipid profiles and multiple indices of whole-body insulin sensitivity were determined. There were no time x treatment interactions for whole-body insulin sensitivity or oral glucose tolerance. The blood lipid profile of fasting subjects did not change after cinnamon supplementation. We conclude that cinnamon supplementation (1.5 g/d) does not improve whole-body insulin sensitivity or oral glucose tolerance and does not modulate blood lipid profile in postmenopausal patients with type 2 diabetes. More research on the proposed health benefits of cinnamon supplementation is warranted before health claims should be made.