Serum apolipoprotein A1 and haptoglobin, in patients with suspected drug-induced liver injury (DILI) as biomarkers of recovery

BACKGROUND

There is a clear need for better biomarkers of drug-induced-liver-injury (DILI).

AIMS

We aimed to evaluate the possible prognostic value of ActiTest and FibroTest proteins apoliprotein-A1, haptoglobin and alpha-2-macroglobulin, in patients with DILI.

METHODS

We analyzed cases and controls included in the IMI-SAFE-T-DILI European project, from which serum samples had been stored in a dedicated biobank. The analyses of ActiTest and FibroTest had been prospectively scheduled. The primary objective was to analyze the performance (AUROC) of ActiTest components as predictors of recovery outcome defined as an ALT <2x the upper limit of normal (ULN), and BILI <2x ULN.

RESULTS

After adjudication, 154 patients were considered to have DILI and 22 were considered to have acute liver injury without DILI. A multivariate regression analysis (ActiTest-DILI patent pending) combining the ActiTest components without BILI and ALT (used as references), apolipoprotein-A1, haptoglobin, alpha-2-macroglobulin and GGT, age and gender, resulted in a significant prediction of recovery with 67.0% accuracy (77/115) and an AUROC of 0.724 (P<0.001 vs. no prediction 0.500). Repeated apolipoprotein-A1 and haptoglobin remained significantly higher in the DILI cases that recovered (n = 65) versus those that did not (n = 16), at inclusion, at 4-8 weeks and at 8-12 weeks. The same results were observed after stratification on APAP cases and non-APAP cases.

CONCLUSIONS

We identified that apolipoprotein-A1 and haptoglobin had significant predictive values for the prediction of recovery at 12 weeks in DILI, enabling the construction of a new prognostic panel, the DILI-ActiTest, which needs to be independently validated.

[The microRNAs as biomarkers: What prospects?]

MicroRNAs are nucleic acids of about twenty nucleotides that regulate about a third of the genome at the post-transcriptional level. Thanks to their different forms of transport, microRNAs are stable and can be detected in biological fluids such as blood, urine, cerebrospinal fluid, or saliva. In addition, the profile of circulating microRNAs is a specific part of the cells in which it is secreted and is modified according to the physiological or pathological conditions of these cells. MicroRNAs therefore appear as biomarkers of interest for many diseases. However, these applications face several challenges because there are currently considerable differences between the sample processing procedures, assay methods, and especially the result standardization strategies. This literature review aims to take stock of the current use of microRNAs as biomarkers mainly in biological fluids and address the perspectives that emerge from the fact that their vesicular circulating forms could be used to assess the state of the cells and the tissues that produce them.

MOG1: a new susceptibility gene for Brugada syndrome

BACKGROUND

Brugada syndrome (BrS) is caused mainly by mutations in the SCN5A gene, which encodes the α-subunit of the cardiac sodium channel Na(v)1.5. However, ≈ 20% of probands have SCN5A mutations, suggesting the implication of other genes. MOG1 recently was described as a new partner of Na(v)1.5, playing a potential role in the regulation of its expression and trafficking. We investigated whether mutations in MOG1 could cause BrS.

METHODS AND RESULTS

MOG1 was screened by direct sequencing in patients with BrS and idiopathic ventricular fibrillation. A missense mutation p.Glu83Asp (E83D) was detected in a symptomatic female patient with a type-1 BrS ECG but not in 281 controls. Wild type (WT)- and mutant E83D-MOG1 were expressed in HEK Na(v)1.5 stable cells and studied using patch-clamp assays. Overexpression of WT-MOG1 alone doubled sodium current (I(Na)) density compared to control conditions (P<0.01). In contrast, overexpression of mutant E83D alone or E83D+WT failed to increase I(Na) (P<0.05), demonstrating the dominant-negative effect of the mutant. Microscopy revealed that Na(v)1.5 channels failed to properly traffic to the cell membrane in the presence of the mutant. Silencing endogenous MOG1 demonstrated a 54% decrease in I(Na) density.

CONCLUSIONS

Our results support the hypothesis that dominant-negative mutations in MOG1 can impair the trafficking of Na(v)1.5 to the membrane, leading to I(Na) reduction and clinical manifestation of BrS. Moreover, silencing MOG1 reduced I(Na), demonstrating that MOG1 is likely to be important in the surface expression of Na(v)1.5 channels. All together, our data support MOG1 as a new susceptibility gene for BrS.

Desmosomal gene analysis in arrhythmogenic right ventricular dysplasia/cardiomyopathy: spectrum of mutations and clinical impact in practice

AIMS

Five desmosomal genes have been recently implicated in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) but the clinical impact of genetics remains poorly understood. We wanted to address the potential impact of genotyping.

METHODS AND RESULTS

Direct sequencing of the five genes (JUP, DSP, PKP2, DSG2, and DSC2) was performed in 135 unrelated patients with ARVD/C. We identified 41 different disease-causing mutations, including 28 novel ones, in 62 patients (46%). In addition, a genetic variant of unknown significance was identified in nine additional patients (7%). Distribution of genes was 31% (PKP2), 10% (DSG2), 4.5% (DSP), 1.5% (DSC2), and 0% (JUP). The presence of desmosomal mutations was not associated with familial context but was associated with young age, symptoms, electrical substrate, and extensive structural damage. When compared with other genes, DSG2 mutations were associated with more frequent left ventricular involvement (P = 0.006). Finally, complex genetic status with multiple mutations was identified in 4% of patients and was associated with more frequent sudden death (P = 0.047).

CONCLUSION

This study supports the use of genetic testing as a new diagnostic tool in ARVC/D and also suggests a prognostic impact, as the severity of the disease appears different according to the underlying gene or the presence of multiple mutations.

Analytical study of three cystatin C assays and their impact on cystatin C-based GFR-prediction equations

BACKGROUND

Cystatin C-based equations are used to estimate GFR. However, three cystatin C immunoassays are on the market. Difference in cystatin C assays could have strong consequences on the accuracy and precision of cystatin C-based equations. We have performed an analytical study of these three assays and studied potential differences between assays on the precision of cystatin C-based equations.

METHODS

We have studied imprecision, recovery, linearity and interferences of the three immunoassays (nephelometric assay from Siemens and turbidimetric assays from Dako and Gentian). The impact of differences in cystatin C assays has been studied for the equations published by Levey (Siemens assay) and Grubb (Dako assay).

RESULTS

Analytical performance of the Dako assay is slightly less high. For cystatin C values below 2.5 mg/L, no statistical difference is found between results given by the Dako and the Gentian assays. So, both assays can be used in the Grubb equation. Cystatin C results are different with the Siemens assay. The Levey equation, built with the Siemens assay, can only be used with cystatin C values measured with this assay. Using the Dako or Gentian assay results in the Levey equation can lead to differences in estimating GFR up to 6 mL/min/1.73 m2. Differences can reach 9.5 mL/min/1.73 m2 if the Siemens assay is used in the Grubb equation.

CONCLUSION

The Siemens and Gentian assays seem analytically more valid than the Dako assay for cystatin C determination. Differences in cystatin C assays can lead to significant differences in cystatin C-based equations. However, these differences seem less important than the differences observed with creatinine and creatinine-based equations.

Female predominance and transmission distortion in the long-QT syndrome

BACKGROUND

Congenital long-QT syndrome is a disorder resulting in ventricular arrhythmias and sudden death. The most common forms of the long-QT syndrome, types 1 and 2, are caused by mutations in the potassium-channel genes KCNQ1 and KCNH2, respectively. Although inheritance of the long-QT syndrome is autosomal dominant, female predominance has often been observed and has been attributed to an increased susceptibility to cardiac arrhythmias in women. We investigated the possibility of an unbalanced transmission of the deleterious trait.

METHODS

We investigated the distribution of alleles for the long-QT syndrome in 484 nuclear families with type 1 disease and 269 nuclear families with type 2 disease, all with fully genotyped offspring. The families were recruited in five European referral centers for the long-QT syndrome. Mutation segregation, sex ratio, and parental transmission were analyzed after correction for single ascertainment.

RESULTS

Classic mendelian inheritance ratios were not observed in the offspring of either female carriers of the long-QT syndrome type 1 or male and female carriers of the long-QT syndrome type 2. Among the 1534 descendants, the proportion of genetically affected offspring was significantly greater than that expected according to mendelian inheritance: 870 were carriers of a mutation (57%), and 664 were noncarriers (43%, P<0.001). Among the 870 carriers, the allele for the long-QT syndrome was transmitted more often to female offspring (476 [55%]) than to male offspring (394 [45%], P=0.005). Increased maternal transmission of the long-QT syndrome mutations to daughters was also observed, possibly contributing to the excess of female patients with autosomal dominant long-QT syndrome.

CONCLUSIONS

Positive selection of the mutated alleles that cause the long-QT syndrome leads to transmission distortion, with increased proportions of mutation carriers among the offspring of affected families. Alleles for the long-QT syndrome are more often transmitted to daughters than to sons.

Increased adiponectin receptor-1 expression in adipose tissue of impaired glucose-tolerant obese subjects during weight loss

OBJECTIVE

To investigate the mRNA expression of adiponectin, AdipoR1 and AdipoR2, the two recently cloned adiponectin receptors and peroxisome proliferator activated receptor (PPAR)gamma2 in adipose tissue of obese individuals before and during a very low calorie diet (VLCD) inducing weight loss.

METHODS

Twenty-three non-diabetic obese subjects with normal (NGT, n = 11) or impaired glucose tolerance (IGT, n = 12) (age, 47 +/- 3 years; body mass index, 39.3 +/- 1.3 kg/m2) were studied before and after a 3-week 3.9 MJ diet daily without exercise. mRNA levels of nine IGT and six NGT subjects were measured by real-time PCR in s.c. abdominal adipose tissue.

RESULTS

Metabolic parameters and insulin sensitivity were improved by VLCD in the IGT group, but minimally affected in the NGT group. VLCD increased expression of AdipoR1 in the IGT (P = 0.02), but not in the NGT group. Adiponectin, AdipoR2 and PPARgamma2 mRNA levels did not change during VLCD in any group. In the IGT, but not in the NGT group, AdipoR1 and AdipoR2 expressions were positively related to that of PPARgamma2 and, after VLCD, AdipoR1 and AdipoR2 expressions were positively related to each other and to that of adiponectin.

CONCLUSION

In the NGT group, the 3-week VLCD inducing weight loss did not modify metabolic parameters, insulin sensitivity and the expression of the adiponectin system in adipose tissue. By contrast, in the IGT group, AdipoR1 expression increased and we found a coordinate regulation of the expression of adiponectin and its receptors. These modifications could participate, through adiponectin action on adipocytes, to the improved metabolic parameters observed in IGT subjects.

A new mutation in PRKAG2 gene causing hypertrophic cardiomyopathy with conduction system disease and muscular glycogenosis

Mutations in the gene encoding the gamma2 subunit of AMP-activated protein kinase (PRKAG2) cause familial cardiac hypertrophy and electrophysiological abnormalities, with glycogen accumulation in the heart of affected patients. The authors describe a 38-year-old man with a new heterozygous PRKAG2 mutation (Ser548Pro) manifesting by hypertrophic cardiomyopathy, severe conduction system abnormalities, and skeletal muscle glycogenosis. Considering those results, PRKAG2 gene could be a potential candidate for unexplained muscle glycogenosis associated with cardiac abnormalities.

Adrénoleucodystrophie liée à l'X chez une proposante symptomatique : présentation clinique, diagnostic biologique et conséquences familiales

INTRODUCTION

X-linked adrenoleukodystrophy (ALD) is the most frequent type of leukodystrophy (1/17 000 males). The phenotypic range in male patients varies from the severe cerebral presentations in children to the milder myeloneuropathy and to isolate adrenal insufficiency. More than a half of the carrier females display clinical symptoms over the age of 40 years.

OBSERVATION

Diagnosis of ALD was raised in a 40 year-old female who presented with spastic paraparesis and sphincterian dysfunction, occurring after the delivery of her first child. There was no family history of ALD. Very long-chain fatty acids (VLFCA) were assayed in her one-year-old son in order to propose appropriate hormonal and neurological survey. His dosage was abnormal and an adrenal insufficiency was subsequently found. A brain MRI will be proposed biannually when he reaches to age of for years. The proband's mother had an increased level of VLCFA, showing that she was a carrier. Family screening was extended to the proband's sisters and maternal aunt who already had children, but also to her brother, who may express a mild form of the disease later on, and to her maternal uncles who might be asymptomatic carriers. A frameshift mutation was found in the ABCD1 gene and will allow accurate carrier identification and prenatal diagnosis in the family.

CONCLUSION

ALD diagnosis should be evoked in a woman affected by myelopathy despite the lack of family history. Such a diagnosis has severe consequences since some of the related males may carry the mutation although they do not display any symptom at time of diagnosis, and because carrier females have a risk to both have a clinical expression of the disease and give birth to an affected boy.

[Alpha 2 macroglobulin immunoturbidimetric assays (DakoCytomation reagents) on Roche Diagnostic analysers (Modular P, Cobas Integra). Application to FibroTest-Actic-Test]

BACKGROUND

Alpha2Macroglobulin (A2M) measure showed a revival since it was introduced into FibroTest-ActiTest-Fibro (FT-AT-Fibro) algorithm. More often than not, this assay is performed in immunonephelemetry. Progresses in the comprehension of fibrosis dynamics and better treatment efficacy follow-up will increase FT-AT-Fibro prescriptions. Despite efforts to standardize methods of enzymatic activity measure and proteins measure, we still observe important interlaboratory and intersystem variability.

AIM

The primary aim of the study is to validate immunoturbidimetric measure of A2M on Modular P and Cobas Integra analysers (Roche Diagnostics) in utility channel using DakoCytomation reagents in order to extend the analytical system range allowed to measure A2M. The secondary aim of the study is to verify transferability of the six FT-AT composants (A2M, haptoglobin, apolipoprotein A1, total bilirubin, GGT and ALT) to Roche Diagnostics equipment by comparing with results measured on the reference system.

RESULTS

A2M measures (n = 146) showed linearity, repetitiveness and were reproducible. Readjustments to adapt A2M measures were required. A corrector factor of 0.84 for Modular P and of 0.87 for Cobas Integra was introduced in order to readjust the immunoturbidimetric method to the immunonephelemetric method. The rationale of proposed corrector factors is based on the use of Dade Behring and DakoCytomation reagents (antisera and calibrant). Biologist vigilance is required to point out modifications or variations in reagents that could be done by the company. The six parameters results transferability from the reference system to Roche Diagnostics was demonstrated by statistic analysis. FT-AT showed excellent correlations to the reference system for Modular P and Cobas Integra analysers. In this study no difference more than 0.11 was recorded and only few subjects had differences between 0.05 and 0.10. Therefore this very low inter-analysers variability has no significant clinical impact.

CONCLUSION

This study showed that the analytical system made of Modular P, Cobas Integra, Roche Diagnostics and DakoCytomation reagents can be used for FibroTest-ActiTest-Fibro parameters assessment. Their statistical and clinical variability were acceptable compared to the reference system.

[Results transferability on RXL, ARX, X-Pand, BN2 (Dade Behring) and modular DP (Roche Diagnostics) analysers: application to component assays of fibrotest and Actitest]

The follow up of patients with chronic liver diseases and the data from multicentric clinical studies are affected by the variability of assay results for the same parameter between the different laboratories. Today, the main objective in clinical chemistry throughout the world is to harmonise the assay results between the laboratories after the confirmation of their traceability, in relation to defined reference systems. In this context, the purpose of our study was to verify the homogeneity of haptoglobin, apolipoprotein A1, total bilirubin, GGT activity, ALAT activity results, which are combined in Fibrotest and Actitest, between Dimension Analysers RXL, ARX and X-PAND (Dade Behring Society). Moreover, we verified the transferability of Fibrotest and Actitest results between the RXL, and either the BN2 (haptoglobin and apolipoprotein A1) or the Modular DP (total bilirubin, GGT and ALAT activity concentrations). The serum samples from 150 hospitalised patients were analysed on the different analysers. Specific protein assays were calibrated using solutions standardised against reference material on Dimension and BN2 analysers. Total bilirubin assays were performed by a diazoreaction on Dimension and Modular DP analysers. The GGT and ALAT activity measurements on the Dimension analysers were performed in accordance with the reference methods defined by the International Federation of Clinical Chemisty and Laboratory Medicine (IFCC). On the Modular, enzyme activity measurements were performed according to the Szasz method (L-gamma- glutamyl-4-nitroanilide as substrate) modified by Persijn and van der Slik (L-gamma- glutamyl-3-carboxy- 4-nitroanilide as substrat) for GGT and according to the IFCC specifications for ALAT. The methods of enzymatic activity measurement were calibrated on the Modular only. Liver fibrosis and necroinflammatory activity indices were determined using calculation algorithms, after having adjusted each component's result of Fibrotest and Actitest for gender and age. Our study has shown, for each parameter, harmonious results between the Dimension analysers and between RXL and BN2- Modular DP. Disregarding alpha-2 macroglobulin which cannot be assayed on RXL, the results of Fibrotest and Actitest were similar as performed on BN2- Modular DP and RXL.

Decreased expression of ABCD4 and BG1 genes early in the pathogenesis of X-linked adrenoleukodystrophy

Childhood cerebral adrenoleukodystrophy (CCER), adrenomyeloneuropathy (AMN) and AMN with cerebral demyelination (AMN-C) are the main phenotypic variants of X-linked adrenoleukodystrophy (ALD). It is caused by mutations in the ABCD1 gene encoding a half-size peroxisomal transporter that has to dimerize to become functional. The biochemical hallmark of ALD is the accumulation of very-long-chain fatty acids (VLCFA) in plasma and tissues. However, there is no correlation between the ALD phenotype and the ABCD1 gene mutations or the accumulation of VLCFA in plasma and fibroblast from ALD patients. The absence of genotype-phenotype correlation suggests the existence of modifier genes. To elucidate the mechanisms underlying the phenotypic variability of ALD, we studied the expression of ABCD1, three other peroxisomal transporter genes of the same family (ABCD2, ABCD3 and ABCD4) and two VLCFA synthetase genes (VLCS and BG1) involved in VLCFA metabolism, as well as the VLCFA concentrations in the normal white matter (WM) from ALD patients with CCER, AMN-C and AMN phenotypes. This study shows that: (1) ABCD1 gene mutations leading to truncated ALD protein are unlikely to cause variation in the ALD phenotype; (2) accumulation of saturated VLCFA in normal-appearing WM correlates with ALD phenotype and (3) expression of the ABCD4 and BG1, but not of the ABCD2, ABCD3 and VLCS genes, tends to be correlated with the severity of the disease, acting early in the pathogenesis of ALD.

Soluble transferrin receptor in hemochromatosis patients during phlebotomy therapy

BACKGROUND

The monitoring of phlebotomies in hemochromatosis patients depends on iron status measured by ferritin and transferrin saturation (TS). However, in the presence of inflammation or liver injury, soluble transferrin receptor (sTfR) determination was proposed to replace ferritin for diagnosing iron deficiency (ID). The present study evaluated performances of sTfR for the prediction of iron deficiency in a large number of hemochromatosis patients under phlebotomy therapy.

METHODS

We studied 52 patients undergoing therapeutic phlebotomies and obtained 2 samples from 37 patients. Biological parameters were determined before each phlebotomy began. Performances of sTfR and TS in the diagnosis of iron deficiency were compared, according to ferritin levels under 12 microg/l.

RESULTS

Ferritin and TS were correlated with removed iron (r=0.473, p<0.005 and r=0.345, p<0.05, respectively) and sTfR was correlated with the decrease in hemoglobin levels induced by phlebotomies (r=-0.678, p<0.0001). Areas under Receiver Operating Characteristics (ROC) curves for sTfR and TS were not statistically different for prediction of iron deficiency and sensitivity/specificity of sTfR at 1.64 mg/l were 67/86%.

CONCLUSIONS

sTfR determination could be used to predict iron depletion induced by phlebotomies when ferritin is of limited interest, to avoid the appearance of anemia.

Intra-laboratory analytical variability of biochemical markers of fibrosis (Fibrotest) and activity (Actitest) and reference ranges in healthy blood donors

Combinations of tests comprising alpha2-macroglobulin, haptoglobin, apolipoprotein Al, gamma-glutamyltransferase, total bilirubin (Fibrotest) and alanine aminotransferase (Actitest) are being developed as alternatives to liver biopsy in patients with chronic hepatitis C. The aim of this study was to assess in the same laboratory the impact of parameter assay variations on Fibrotest and Actitest results and intra-patient reproducibility of the two tests. The stability of the samples for each test was studied after storage at -80 degrees C and -20 degrees C. Within-run, between-run and total imprecision for each parameter assay, and for Fibrotest and Actitest results, were determined. Transferability of assay results between different analyzers was studied. Intra-patient reproducibility was assessed in 55 hospitalized patients. Fibrotest and Actitest reference ranges were determined in 300 blood donors (reference group). The stability of the parameters was affected by serum storage at -20 degrees C only. The impact of parameter analytical variability on Fibrotest and Actitest results was less than 10% and intra-patient reproducibility was acceptable (p > 0.05). The transferability between different analyzers of results of assays performed under the same standardized and calibration conditions was excellent. Fibrotest and Actitest reference ranges in blood donors were (mean+/-SE) 0.075+/-0.004 and 0.068+/-0.004, respectively. The low intra-laboratory and intra-patient variability in Fibrotest and Actitest results confirm Fibrotest and Actitest reliability.

New mutations of SCN4A cause a potassium-sensitive normokalemic periodic paralysis

BACKGROUND

Periodic paralysis is classified into hypokalemic (hypoPP) and hyperkalemic (hyperPP) periodic paralysis according to variations of blood potassium levels during attacks.

OBJECTIVE

To describe new mutations in the muscle sodium channel gene SCN4A that cause periodic paralysis.

METHODS

A thorough clinical, electrophysiologic, and molecular study was performed of four unrelated families who presented with periodic paralysis.

RESULTS

The nine affected members had episodes of muscle weakness reminiscent of both hyperPP and hypoPP. A provocative test with potassium chloride was positive in two patients. However, repeated and carefully performed tests of blood potassium levels during attacks resulted in normal potassium levels. Remarkably, two patients experienced hypokalemic episodes of paralysis related to peculiar provocative factors (corticosteroids and thyrotoxicosis). Similarly to hyperPP, electromyography in nine patients revealed increased compound muscle action potentials after short exercise and a delayed decline during rest after long exercise as well as myotonic discharges in one patient. With use of molecular genetic analysis of the gene SCN4A, three new mutations were found affecting codon 675. They resulted in an amino acid substitution of a highly conserved arginine (R) to either a glycine (G), a glutamine (Q), or a tryptophan (W). Interestingly, hypoPP is caused by both mutations affecting nearby codons as well as the change of an arginine into another amino acid.

CONCLUSION

A potassium-sensitive and normokalemic type of periodic paralysis caused by new SCN4A mutations at codon 675 is reported.

New KCNQ1 mutations leading to haploinsufficiency in a general population; Defective trafficking of a KvLQT1 mutant

OBJECTIVE

KCNQ1 mutations lead to the long QT syndrome (LQTS), characterized by a prolonged QT interval, syncopes and sudden death. However, some mutations are associated with non-penetrant phenotype (no symptoms, QTc normal or borderline). The objective of this study was to determine whether KCNQ1 variants are associated with borderline QTc prolongation in a general population and to evaluate the frequency of carriers.

METHODS

We selected 2008 unrelated and untreated healthy individuals from a non-patient population. The KCNQ1 gene was screened by denaturing high-performance liquid chromatography (dHPLC) in 50 men and 50 women presenting the longest QTc intervals (403 to 443 ms).

RESULTS

We identified a nonsense mutation, Y148X, and an in-frame deletion of the serine residue 276 (DeltaS276), in S2 and S5 transmembrane domains, respectively. DeltaS276 KvLQT1 channels expressed in COS-7 cells failed to conduct any K+ current in the homozygous state. Besides, a slight reduction in channel activity was observed when coexpressed with WT KvLQT1 and IsK. Confocal microscopy performed on transfected COS-7 cells revealed that DeltaS276 KvLQT1 was retained in the endoplasmic reticulum, whereas WT KvLQT1 was localized in the cell membrane. The two mutation carriers presented borderline QTc interval prolongation at slow heart rate but a 24-h ECG recording revealed a marked QTc prolongation at higher heart rate for the Y148X carrier.

CONCLUSIONS

In this population, two subjects with borderline QTc prolongations (438 and 443 ms) were carriers of KCNQ1 mutations leading to haploinsufficiency and are potentially at risk of developing drug-induced arrhythmia. The study provides the first demonstration of a defective cell surface localization of a KvLQT1 mutant missing one amino acid in a transmembrane domain.

[Influence of pyridoxal phosphate in measuring aminotransferases activities in patients with viral hepatitis]

Effect of a pyridoxal phosphate (PP) supplementation of reagents used for ALT and AST measurement was studied in serum of 20 patients suffering from viral hepatitis. Measurements of enzyme activities were carried out at 37 degrees C, using an automate (AU 600, Olympus). Significant differences (p < 0.0001) were observed both for ALT and AST, meanwhile they were more marked for ALT than for AST. This difference was associated with a strong interindividual variability regarding PP activation effect on ALT. In conclusion, aminotransferase measurements should be carried out with a reagent supplemented with PP, when the enzyme activity is used to evaluate a cytolysis. The same recommendation applies when ALT results are integrated into various combinations developed for the evaluation of liver status.

Overview of the diagnostic value of biochemical markers of liver fibrosis (FibroTest, HCV FibroSure) and necrosis (ActiTest) in patients with chronic hepatitis C

Background

Recent studies strongly suggest that due to the limitations and risks of biopsy, as well as the improvement of the diagnostic accuracy of biochemical markers, liver biopsy should no longer be considered mandatory in patients with chronic hepatitis C. In 2001, FibroTest ActiTest (FT-AT), a panel of biochemical markers, was found to have high diagnostic value for fibrosis (FT range 0.00–1.00) and necroinflammatory histological activity (AT range 0.00–1.00). The aim was to summarize the diagnostic value of these tests from the scientific literature; to respond to frequently asked questions by performing original new analyses (including the range of diagnostic values, a comparison with other markers, the impact of genotype and viral load, and the diagnostic value in intermediate levels of injury); and to develop a system of conversion between the biochemical and biopsy estimates of liver injury.

Results

A total of 16 publications were identified. An integrated database was constructed using 1,570 individual data, to which applied analytical recommendations. The control group consisted of 300 prospectively studied blood donors. For the diagnosis of significant fibrosis by the METAVIR scoring system, the areas under the receiver operating characteristics curves (AUROC) ranged from 0.73 to 0.87. For the diagnosis of significant histological activity, the AUROCs ranged from 0.75 to 0.86. At a cut off of 0.31, the FT negative predictive value for excluding significant fibrosis (prevalence 0.31) was 91%. At a cut off of 0.36, the ActiTest negative predictive value for excluding significant necrosis (prevalence 0.41) was 85%. In three studies there was a direct comparison in the same patients of FT versus other biochemical markers, including hyaluronic acid, the Forns index, and the APRI index. All the comparisons favored FT (P < 0.05). There were no differences between the AUROCs of FT-AT according to genotype or viral load. The AUROCs of FT-AT for consecutive stages of fibrosis and grades of necrosis were the same for both moderate and extreme stages and grades. A conversion table was constructed between the continuous FT-AT values (0.00 to 1.00) and the expected semi-quantitative fibrosis stages (F0 to F4) and necrosis grades (A0 to A3).

Conclusions

Based on these results, the use of the biochemical markers of liver fibrosis (FibroTest) and necrosis (ActiTest) can be recommended as an alternative to liver biopsy for the assessment of liver injury in patients with chronic hepatitis C. In clinical practice, liver biopsy should be recommended only as a second line test, i.e., in case of high risk of error of biochemical tests.

Systemic low-grade inflammation is related to both circulating and adipose tissue TNFalpha, leptin and IL-6 levels in obese women

OBJECTIVE

We assessed the relationships between four circulating acute phase proteins and the circulating and adipose tissue levels of three adipocytokines.

SUBJECTS

In all, 15 nondiabetic obese women with a body mass index (BMI) above 32 kg/m(2) were investigated.

METHOD

Circulating concentrations of C-reactive protein (CRP), alpha 1 acid glycoprotein (AAG), fibrinogen, alpha 1 antitrypsin and both circulating and adipose tissue levels of interleukin (IL)-6, tumor necrosis factor (TNF)alpha and leptin were measured by either nephelometry or enzyme-linked immunosorbent assay.

RESULTS

We found a strong positive correlation between both circulating and adipose tissue levels of IL-6, TNFalpha and leptin and serum CRP levels. All these adipose tissue adipocytokines were also positively correlated with serum AAG levels. These correlations disappeared when adjusted for fat mass, suggesting that the relationship observed was dependent on fat amount.

CONCLUSION

Our results indicate a strong relationship between adipocytokines and inflammatory markers, and suggest that cytokines secreted by adipose tissue in obese subjects could play a role in increased inflammatory proteins secretion by the liver.

Low incidence of cardiac events with ?-blocking therapy in children with long QT syndrome

AIMS

To evaluate the effect of beta-blockers in children with long QT syndrome (LQTS) we reviewed the outcome of 122 patients (pts).

METHODS

LQTS was diagnosed in 24 neonates and in 98 pts aged 0.5-15 years. Diagnosis was made because of syncope in 51 pts, bradycardia in 10 neonates and family history in 61 pts. The longest QTc ranged from 400 to 700 ms. Thirteen pts had 2:1 atrioventricular block and/or ventricular arrhythmias. Screening for mutations was performed in 118 pts. All children were treated with beta-blockers, annually checked by exercise testing and/or 24 h ECG monitoring.

RESULTS

Four pts died. Survivors were followed-up for 1-18 years (7.5 +/- 5.3 years). Five neonates and 3 older pts received a prophylactic pacemaker (1 death) so that only 111/122 pts survived and were followed-up with beta-blockers alone. None of them died and five experienced a non-fatal cardiac event. There was no cardiac event among pts who were diagnosed because of familial history and among symptomatic KCNQ1 pts who were effectively treated with beta-blockers.

CONCLUSION

The outcome of children with LQTS under effective beta-blockers is favourable. Persisting arrhythmia or symptoms despite beta-blockers should aim at identifying other genotypes than KCNQ1.

Intra-individual fasting versus postprandial variation of biochemical markers of liver fibrosis (FibroTest) and activity (ActiTest)

BACKGROUND: Biochemical marker combinations, including alpha2-macroglobulin, haptoglobin, apolipoprotein A1, gamma-glutamyl transpeptidase, and total bilirubin (all part of FibroTest) plus alanine aminotransferase (all part of ActiTest), are being developed as alternatives to liver biopsy in patients with chronic hepatitis C and other various chronic liver diseases. Considering this premise, the primary aim of this study was to assess the impact of meal intake on FibroTest and ActiTest results. Such studies are very important for patients, as many clinical errors have been related to the absence of baseline evidence. RESULTS: Intra-individual variation was assessed for the 6 above components and for FibroTest and ActiTest, by measuring time dependent variations before and one hour after a standard meal in 64 subjects. These consisted of 29 healthy volunteers and 35 patients with chronic liver diseases. Meal intake had no significant impact on any of the six components, or on FibroTest or ActiTest, as assessed by repeated measure variance analyses (ANOVA all p > 0.90); the Spearman correlation coefficient ranged from 0.87 (total bilirubin) to 0.995 (gamma-glutamyl transpeptidase). The coefficients of variation (CV) between fasting and postprandial measurements fluctuated for the six components from 0.09 (apolipoprotein A1) to 0.14 (alpha2-macroglobulin), and from 0.09 for FibroTest to 0.13 for ActiTest. In contrast, meal intake had a significant impact on triglycerides (ANOVA p = 0.01, CV = 0.65) and glucose (ANOVA p = 0.04, CV = 0.31). As for the prediction of liver injury, the concordance between fasting and postprandial predicted histological stages and grades was almost perfect, both for FibroTest (kappa = 0.91, p < 0.001) and ActiTest (kappa = 0.80, p < 0.001). CONCLUSIONS: The intra-individual variation of biochemical markers was low, and it was shown that measurements of FibroTest, ActiTest and their components are not significantly modified by meal intake. This fact makes the screening of patients at risk of chronic liver diseases more convenient.

Adiponutrin: A new gene regulated by energy balance in human adipose tissue

Adiponutrin is a newly identified nonsecreted adipocyte protein regulated by changes in energy balance in rodents. We documented the influence of energy balance modification on adiponutrin gene expression in humans. We investigated the mRNA expression in sc adipose tissue of nonobese women and in obese women during 2-d very low-calorie diet (VLCD) and subsequent refeeding as well as before and after a VLCD of 3 wk (21-d VLCD). The adiponutrin mRNA levels of the nonobese and obese women were not different (P > 0.05). Two-day VLCD reduced the average level of adiponutrin mRNA expression by 36% (P = 0.0016), whereas refeeding elevated the mRNA level by 31% (P = 0.004). The 3-wk VLCD caused a dramatic 58% fall of the adiponutrin mRNA expression level (P = 0.001). The mRNA level was negatively correlated with fasting glucose (Rho = -0.62; P < 0.0001), and subjects with high adiponutrin mRNA level had an increased insulin sensitivity. Compared with other adipocyte proteins such as leptin and adiponectin, adiponutrin mRNA did not show correlation with either adiposity indexes or with leptin or adiponectin mRNAs. These results indicate that adiponutrin gene expression in humans is highly regulated by changes in energy balance.

[Neonatal forms of congenital long QT syndrome]

The neonatal congenital long QT syndrome (LQTS) is rare and of bad prognosis due to the presence of severe ventricular arrhythmia and conduction abnormalities.

METHODS

we included 24 propositus newborns from our population with LQTS. Genetic study was possible in 19 cases.

RESULTS

the diagnosis of LQTS was made according to a QT prolongation associated with a sinusal neonatal bradycardia (n=9) or a 2/1 AV block (n=15). The onset presentation consisted of syncope (n=2), torsades de pointes (n=7), cardiovascular collapse (n=5), cardiac arrest (n=1). The mean QTc was at 550+60 ms. During the neonatal period the treatment consisted of beta-blocking agents in all cases, associated with a definitive pacemaker implantation in 10 cases with 2/1 AV block. Three newborns with a 2/1 AV block died during the first month of life (one case due to a septecemia after implantation of a pacemaker, and two who were waiting for that implantation). All survivors remained asymptomatic during a follow-up period of 7 years. In all cases with a 2/1 AV block we identified mutations in HERG (n=8). Newborns with isolated sinusal bradycardia presented all a mutation in KCNQ1 (n=9).

CONCLUSION

the LTQS with 2/1 AV block is preferably associated with mutation in HERO with a bad initial prognosis.

Long QT syndrome in neonates: conduction disorders associated with HERG mutations and sinus bradycardia with KCNQ1 mutations

OBJECTIVES

We hypothesized that neonatal long QT syndrome (LQTS) with 2:1 atrioventricular block (AVB) could be related to HERG mutations.

BACKGROUND

Early onset of LQTS is rare but carries a high risk of life-threatening events such as ventricular arrhythmias and conduction disorders. There are no data on possible gene specificity.

METHODS

We analyzed the characteristics and outcomes of 23 neonate probands from our LQTS population. Samples of DNA were available in 18 cases.

RESULTS

Long QT syndrome was diagnosed because of corrected QT interval (QTc) prolongation (mean QTc of 558 +/- 62 ms) and neonatal bradycardia attributable to sinus bradycardia (n = 8) or 2:1 AVB (n = 15). Symptoms included syncope (n = 2), torsades de pointes (n = 7), and hemodynamic failure (n = 6). Three infants with 2:1 AVB died during the first month of life. During the neonatal period, all living patients received beta-blockers (BB) and 13 had a combination of BB and permanent cardiac pacing. Under treatment, patients remained asymptomatic, with a mean follow-up of seven years. Mutations were identified in HERG (n = 8) and KCNQ1 (n = 8), and one child had three mutations (HERG, KCNQ1, and SCN5A). Conduction disorders were associated with LQT2, whereas sinus bradycardia was associated with LQT1.

CONCLUSIONS

Two-to-one AVB seems preferentially associated with HERG mutations, either isolated or combined. Long QT syndrome with relative bradycardia attributable to 2:1 AVB has a poor prognosis during the first month of life. In contrast, sinus bradycardia seems to be associated with KCNQ1 mutations, with a good short-term prognosis under BB therapy.

Lack of association of the potassium channel-associated peptide MiRP2-R83H variant with periodic paralysis

A missense variant (R83H) of the gene (KCNE3) encoding a potassium channel-associated peptide, MinK-related peptide 2 (MiRP2), has been reported in periodic paralysis patients. In the current study, no difference in the frequency of the MiRP2-R83H variant between periodic paralysis patients and healthy individuals was found. Furthermore, there was no segregation of this gene variant with the disease. These observations weaken the proposal that MiRP2-R83H causes periodic paralysis.

Identification of the genotypes causing hypertrophic cardiomyopathy in northern Sweden

Hypertrophic cardiomyopathy (HCM) is a heterogenous disease, with variable genotypic and phenotypic expressions, often caused by mutations in sarcomeric protein genes. The aim of this study was to identify the genotypes and associated phenotypes related to HCM in northern Sweden. In 46 unrelated individuals with familial or sporadic HCM, mutation analysis of eight sarcomeric protein genes was performed; the cardiac beta-myosin heavy chain, cardiac myosin-binding protein C, cardiac troponin T, alpha-tropomyosin, cardiac essential and regulatory myosin light chains, cardiac troponin I and cardiac alpha-actin. A total of 11 mutations, of which six were novel ones, were found in 13 individuals. Seven mutations were located in the myosin-binding protein C gene, two in the beta-myosin heavy chain gene and one in the regulatory myosin light chain and troponin I genes, respectively. This is the first Swedish study, where a population with HCM has been genotyped. Mutations in the cardiac myosin-binding protein C gene were the most common ones found in northern Sweden, whereas mutations in the beta-myosin heavy chain gene were less frequent than previously described. There are differences in the phenotypes mediated by these genes characterised by a more late-onset disease for the myosin-binding protein C gene mutations. This should be taken into consideration, when evaluating clinical findings in the diagnosis of the disease, especially in young adults in families with HCM, where penetrance can be expected to be incomplete in the presence of a myosin-binding protein C gene mutation.

Hypertrophic cardiomyopathy: distribution of disease genes, spectrum of mutations, and implications for a molecular diagnosis strategy

BACKGROUND

Hypertrophic cardiomyopathy is an autosomal-dominant disorder in which 10 genes and numerous mutations have been reported. The aim of the present study was to perform a systematic screening of these genes in a large population, to evaluate the distribution of the disease genes, and to determine the best molecular strategy in clinical practice.

METHODS AND RESULTS

The entire coding sequences of 9 genes (MYH7, MYBPC3, TNNI3, TNNT2, MYL2, MYL3, TPM1, ACTC, andTNNC1) were analyzed in 197 unrelated index cases with familial or sporadic hypertrophic cardiomyopathy. Disease-causing mutations were identified in 124 index patients ( approximately 63%), and 97 different mutations, including 60 novel ones, were identified. The cardiac myosin-binding protein C (MYBPC3) and beta-myosin heavy chain (MYH7) genes accounted for 82% of families with identified mutations (42% and 40%, respectively). Distribution of the genes varied according to the prognosis (P=0.036). Moreover, a mutation was found in 15 of 25 index cases with "sporadic" hypertrophic cardiomyopathy (60%). Finally, 6 families had patients with more than one mutation, and phenotype analyses suggested a gene dose effect in these compound-heterozygous, double-heterozygous, or homozygous patients.

CONCLUSIONS

These results might have implications for genetic diagnosis strategy and, subsequently, for genetic counseling. First, on the basis of this experience, the screening of already known mutations is not helpful. The analysis should start by testing MYBPC3 and MYH7 and then focus on TNNI3, TNNT2, and MYL2. Second, in particularly severe phenotypes, several mutations should be searched. Finally, sporadic cases can be successfully screened.

Interpretation of circulating C-reactive protein levels in adults: body mass index and gender are a must

OBJECTIVE

The recently demonstrated association between C-reactive protein (CRP) level and body mass index (BMI) raised the question of the link between CRP and the degree of obesity. In the present study, we measured CRP in a healthy population with a wide range of BMI in order to appreciate the influence of overweight in the interpretation of CRP results in clinical use.

METHOD

Blood donors, aged from 19 to 65 years, were included in the study. According to BMI, subjects were classified into 3 groups: A (BMI<25 kg/m(2), n=611); B (25-30, n=147); C (> 30, n=34).

RESULTS

CRP values were different among women and men. CRP progressively increased with BMI in women. These results clearly showed that average level of CRP was quite different according to BMI and gender of the subjects and generated different normal ranges of CRP expressed in mg/L (median, 75(th) percentile): Group A: women: 0.44, 0.93; men: 0.40, 0.79, Group B: women: 1.28, 1.84; men: 0.84, 2.17, Group C: women: 3.61, 7.21; men: 1.16, 3.08.

CONCLUSION

Our results suggest that for an inflammatory disease diagnosis, a CRP concentration of 5 mg/L is normal for obese women but is five times the 75(th) percentile for normal people.

Genetic testing and genetic counselling in hypertrophic cardiomyopathy: the French experience

AIMS

A major breakthrough in the molecular genetics of hypertrophic cardiomyopathy (HCM) has made genetic testing now available in clinical practice, raising new questions about its implications, potential benefits, and the organisation of the procedure. The aim of this work was (1) to discuss the different questions related to genetic testing in HCM, and propose guidelines for the different situations, (2) to report our preliminary experience with a specific procedure.

METHODS AND RESULTS

The main questions asked by patients and relatives concern presymptomatic diagnosis and prenatal counselling/diagnosis, while clinicians sometimes discuss diagnostic and prognostic testing. To take into account the complex medical and psychological implications of this new approach, we developed a specific, multidisciplinary, and multiple step procedure, including a cardiologist, a geneticist, and a psychologist. Seventy subjects were examined, including (1) 29 adults for presymptomatic diagnosis (of whom 10 left the procedure after the first visit and 19 continued, among whom six had a mutation and two experienced negative psychological impact, observed during follow up), (2) nine couples of parents for presymptomatic diagnosis in their children (the procedure was stopped after the first visit in eight and continued in one), (3) 22 couples for prenatal counselling (no prenatal genetic testing was asked for after the first visit), and (4) 10 subjects for diagnostic testing. We decided to perform no prognostic testing.

CONCLUSION

Our preliminary experience confirms the complexity of the situation and suggests the necessity for a specific procedure to ensure good practice in genetic testing of HCM.

Adipose tissue IL-6 content correlates with resistance to insulin activation of glucose uptake both in vivo and in vitro

Obesity and type 2 diabetes are associated with insulin resistance, the mechanisms of which remain poorly understood. A significant correlation between circulating IL-6 level and insulin sensitivity has recently been found in humans. Because adipose tissue could be a significant source of IL-6, we analyzed the relationship between the levels of adipose tissue IL-6 and insulin action in vivo, during a hyperinsulinemic normoglycemic clamp, and in vitro by measuring glucose transport in adipocytes from 12 obese subjects with (n = 7) or without (n = 5) diabetes. We observed an inverse correlation between adipose tissue IL-6 content and maximal insulin-responsiveness measured in vivo (P < 0.02) and in vitro (P < 0.02). Conversely, there was no significant correlation between these two later parameters and adipose tissue leptin or tumor necrosis factor-alpha protein contents. Furthermore, we showed, for the first time, the presence of immunoreactive IL-6 receptors in the plasma membrane of human abdominal sc adipocytes. This suggests that locally secreted IL-6 could act on adipocytes by an autocrine/paracrine mechanism. In conclusion, increased IL-6 production by sc adipose cells might participate to the insulin-resistant state observed in human obesity.

Eicosapentaenoic acid induces mRNA expression of peroxisome proliferator-activated receptor gamma

OBJECTIVE

To verify whether polyunsaturated fatty acids (PUFAs) can regulate the expression of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) in human adipose tissue.

RESEARCH METHODS AND PROCEDURES

The effect of various PUFAS on PPARgamma1 and -gamma2 mRNA expression was investigated in freshly isolated adipocytes prepared from fat samples obtained during surgery. PPARgamma mRNA levels were also determined in subcutaneous adipose tissue biopsies of 11 obese women, in the fasting state, to search for in vivo associations between PPARgamma expression and plasma PUFA concentrations. PPARgamma mRNA levels were determined by reverse-transcription competitive polymerase chain reaction.

RESULTS

Eicosapentaenoic acid (EPA) significantly increased PPARgamma1 mRNA levels in isolated adipocytes, without affecting the expression of PPARgamma2. The other tested fatty acids (linolenic acid, docosahexaenoic acid and omega-6 PUFAs) had no effect. The effect of EPA was dependent on the concentration (maximal effect after 6 hours with 50 microM) and was not reproduced by activators of the different members of the PPAR family. In addition, a strong positive correlation was found between plasma EPA concentrations and PPARgamma mRNA levels in adipose tissue of obese subjects.

DISCUSSION

Our results demonstrate that adipose tissue PPARgamma1 mRNA concentration is positively regulated by EPA, suggesting that the composition of dietary lipids may affect PPARgamma gene expression in vivo in humans. These data also suggest that an induction of the expression of this nuclear receptor isoform might be involved in the mechanism of action of EPA and in some of its beneficial effects.

Adipose tissue IL-6 content correlates with resistance to insulin activation of glucose uptake both in vivo and in vitro

Obesity and type 2 diabetes are associated with insulin resistance, the mechanisms of which remain poorly understood. A significant correlation between circulating IL-6 level and insulin sensitivity has recently been found in humans. Because adipose tissue could be a significant source of IL-6, we analyzed the relationship between the levels of adipose tissue IL-6 and insulin action in vivo, during a hyperinsulinemic normoglycemic clamp, and in vitro by measuring glucose transport in adipocytes from 12 obese subjects with (n = 7) or without (n = 5) diabetes. We observed an inverse correlation between adipose tissue IL-6 content and maximal insulin-responsiveness measured in vivo (P < 0.02) and in vitro (P < 0.02). Conversely, there was no significant correlation between these two later parameters and adipose tissue leptin or tumor necrosis factor-alpha protein contents. Furthermore, we showed, for the first time, the presence of immunoreactive IL-6 receptors in the plasma membrane of human abdominal sc adipocytes. This suggests that locally secreted IL-6 could act on adipocytes by an autocrine/paracrine mechanism. In conclusion, increased IL-6 production by sc adipose cells might participate to the insulin-resistant state observed in human obesity.

Hypokalaemic periodic paralysis type 2 caused by mutations at codon 672 in the muscle sodium channel gene SCN4A

Hypokalaemic periodic paralysis (hypoPP) is an autosomal dominant muscle disorder characterized by episodic attacks of muscle weakness associated with a decrease in blood potassium levels. Mutations in the gene encoding the skeletal muscle voltage-gated calcium channel alpha-1 subunit (CACNL1A3) account for the majority of cases. Recently, mutations in the gene coding for the skeletal muscle voltage-gated sodium channel alpha subunit (SCN4A) have been reported in a small number of hypoPP families. In order to determine the relative frequency of the CANCL1A3 and SCN4A mutations in a large population of hypoPP patients, and to specify the clinical and pathological features associated with each of them, we searched for mutations in 58 independent hypoPP index cases. We detected the causative mutation in 45 cases: 40 were linked to the CACNL1A3 gene and five to the SCN4A gene. One mutation has not been described before. Some remarkable clinical features were observed in a large hypoPP family carrying an SCN4A mutation: a complete penetrance in men and women, an early age at onset, postcritic myalgias and an increased number and severity of attacks induced by acetazolamide. A muscle biopsy, performed in two members of this family, revealed a peculiar myopathy characterized by tubular aggregates. In contrast, vacuoles were predominant in muscles from hypoPP patients carrying CACNL1A3 mutations. Our findings point to the usefulness of a molecular characterization of hypoPP patients in clinical practice. They also provide new clues for understanding the mechanisms behind functional and structural alterations of the skeletal muscle in hypoPP.