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Short chain fatty acids (SCFAs) are primarily produced in the caecum and proximal colon via the bacterial fermentation of undigested carbohydrates that have avoided digestion in the small intestine. Increasing evidence supports the critical role that SCFAs play in health and homeostasis. Microbial SCFAs, namely butyric acid, serve as a principal energy source for colonocytes, and their production is essential for gut integrity. A direct link between SCFAs and some human pathological conditions, such as inflammatory bowel disease, irritable bowel syndrome, diarrhea, and cancer, has been proposed. The direct measurement of SCFAs in feces provides a non-invasive approach to demonstrating connections between SCFAs, microbiota, and metabolic diseases to estimate their potential applicability as meaningful biomarkers of intestinal health. This study aimed to adapt a robust analytical method (liquid–liquid extraction, followed by isobutyl chloroformate derivatization and GC–MS analysis), with comparable performances to methods from the literature, and to use this tool to tackle the question of pre-analytical conditions, namely stool processing. We focused on the methodology of managing stool samples before the analysis (fresh stool or dilution in either ethanol/methanol, lyophilized stool, or RNAlater®), as this is a significant issue to consider for standardizing results between clinical laboratories. The objective was to standardize methods for future applications as diagnostic tools. In this paper, we propose a validated GC–MS method for SCFA quantification in stool samples, including pre- and post-analytical comparison studies that could be easily used for clinical laboratory purposes. Our results show that using lyophilization as a stool-processing method would be the best method to achieve this goal. [ABSTRACT FROM AUTHOR]

Reshaping the intestinal microbiota by the ingestion of fiber, such as pectin, improves alcohol-induced liver lesions in mice by modulating bacterial metabolites, including indoles, as well as bile acids (BAs). In this context, we aimed to elucidate how oral supplementation of pectin affects BA metabolism in alcohol-challenged mice receiving feces from patients with alcoholic hepatitis. Pectin reduced alcohol liver disease. This beneficial effect correlated with lower BA levels in the plasma and liver but higher levels in the caecum, suggesting that pectin stimulated BA excretion. Pectin modified the overall BA composition, favoring an augmentation in the proportion of hydrophilic forms in the liver, plasma, and gut. This effect was linked to an imbalance between hydrophobic and hydrophilic (less toxic) BAs in the gut. Pectin induced the enrichment of intestinal bacteria harboring genes that encode BA-metabolizing enzymes. The modulation of BA content by pectin inhibited farnesoid X receptor signaling in the ileum and the subsequent upregulation of Cyp7a1 in the liver. Despite an increase in BA synthesis, pectin reduced BA serum levels by promoting their intestinal excretion. In conclusion, pectin alleviates alcohol liver disease by modifying the BA cycle through effects on the intestinal microbiota and enhanced BA excretion. [ABSTRACT FROM AUTHOR]

• Homocysteine metabolism is complex and dependent on vitamins as cofactors. • Here is described the case of a patient with a 1562 μmol/L plasma homocysteine concentration. • Association of secondary etiologies may lead to major hyperhomocysteinemia. The metabolism of homocysteine is complex and involves many enzymes as well as vitamin-derived cofactors. Any dysregulation of this metabolism may lead to hyperhomocysteinemia (HHCy) which is responsible for many clinical disorders including thromboembolic events. HHCy may result from very different etiologies and is generally classified into three groups according to homocysteine concentrations: moderate (<30 µmol/L), intermediate (30–100 µmol/L) or major (>100 μmol/L). Major HHCy cases are generally due to monogenic defects of key enzymes involved in homocysteine metabolism, such as cystathionine-β-synthase or 5,10-methylene-tetrahydrofolate reductase, or to any defect in vitamin B 12 absorption, transport or metabolism. By contrast, moderate and intermediate HHCy tend to result from so-called "secondary" etiologies (e.g. tobacco, drugs, alcohol, vitamin deficiencies or pathological contexts). Here we describe the case of a patient with an unusually high plasma homocysteine concentration (1562 μmol/L) which was only explained by a combination of such secondary etiologies, among them chronic renal failure, hypothyroidism, the homozygous C677T MTHFR variant, a novel heterozygous variant of the MSR gene, and a vitamin deficiency. In addition, this patient exhibited a spectacular decline in homocysteine concentrations (returning to normal) after betaine and vitamin administration. In conclusion, this case highlights that major HHCy may also result from the combination of secondary etiologies, with vitamin deficiency as a triggering factor. [ABSTRACT FROM AUTHOR]

Introduction: Haemoglobin A1c (HbA1c) is a key analyte for the monitoring of glycemic balance in diabetic patients and is used for diabetes diagnosis in many countries. The potential interference of carbamylated haemoglobin (cHb) and labile glycated haemoglobin (LA1c) on HbA1c assays must remain a matter of vigilance. Such a situation has occurred in our laboratory with a kit replacement on the Bio-Rad Variant? II testing system, a cation-exchange high performance liquid chromatography (HPLC) system. With this method, LA1c and cHb coeluted in a same peak which may have different consequences on HbA1c values. Materials and methods: The influence of increasing LA1c and cHb values on HbA1c results was studied with in vitro glycation and carbamylation of samples. Samples from patients with high and normal blood urea concentrations were assayed by HPLC and immunological assay. Results: We observed that the degree of interference greatly varied depending on the nature of the interfering Hb fractions found under the socalled "LA1c peak". Thus, we have decided to apply a decision tree using "LA1c" thresholds depending on: (i) the retention time, (ii) the shape of the peak, (iii) other analytes, like urea. If the peak recognized as "LA1c" is mainly formed by LA1c, we consider that there is no interference until 4%. If the peak is mainly formed by cHb, we consider an interference threshold equal to 2%. Conclusions: This situation reminds that cHb and LA1c remain critical issues in chromatography-based HbA1c assays and that adapted criteria must be set up for result interpretation. [ABSTRACT FROM AUTHOR]

Background: Glycated hemoglobin (HbA1c) is widely used for the monitoring of glycemic balance in diabetic patients and has also been proposed as a tool for the diagnostic of diabetes mellitus. Accordingly, HbA1c quantification must be performed using robust, reliable and efficient methods. Here are reported the results of the evaluation of a new high performance liquid chromatography (HPLC) system for HbA1c quantification, the D-100™ system from Bio-Rad Laboratories. Methods: The analytical performances of the method as well as the influence of the most frequent interferences regarding HbA1c assays (e.g., labile HbA1c, carbamylated hemoglobin, high HbF) have been tested. Results: Intra- and between-assay CVs were respectively lower than 0.93% and 1.46% (HbA1c results expressed in NGSP units) and lower than 1.67% and 2.27% (HbA1c results expressed in IFCC units). The linearity proved to be excellent from 15 mmol/mol (3.5%) to 184 mmol/mol (19.0%) (r = 0.999). The results were well correlated with those obtained by another HPLC method (VARIANT™ II Hemoglobin A1c Program reorder pack 270-2101NU-Bio-Rad): HbA1c [VARIANT™ II, mmol/mol] = 1.013 x HbA1c [D-100™, mmol/mol]+0.637 (r = 0.993, n = 2000). The D-100™ system provided results consistent with IFCC-assigned external quality control samples and the presence of labile HbA1c, carbamylated hemoglobin and HbF did not interfere with HbA1c measurement. Conclusions: The D-100™ system proved to be a robust and reliable method for HbA1c measurement suitable for routine practice in clinical chemistry laboratories. [ABSTRACT FROM AUTHOR]

Background: An autopsy case of a two-month-old male infant who suddenly and unexpectedly died during his sleep, eight days after the onset of benign varicella. Objectives: To describe post-mortem combined histological and tissue molecular biological techniques for the diagnosis of cytomegalovirus and varicella zoster virus co-infection as a cause of death. Study design: Real-time quantitative PCR and RT-PCR assays for Herpesviruses, respiratory viruses, Adenovirus, Enterovirus and Parvovirus B19 were performed on multi-organ frozen samples and paraffin-embedded tissues in combination with histology. Results: Cytomegalovirus and varicella zoster virus were detected by molecular biology with highest viral loads detected in the lungs (4.6×107 and 1.9×105 genome copies per million of cells, respectively). Pulmonary extensive necrotizing inflammation and immunohistochemistry correlated to virological data. Virological molecular biology was negative on paraffin-embedded tissues. Conclusions: This case shows that thorough quantitative virological investigations on frozen tissues must be performed in combination with histology and immunohistochemistry for the determination of the cause of a sudden unexplained infant death. [ABSTRACT FROM AUTHOR]

This article reports on four cases of glycated hemoglobin (HbA1c) assays performed in patients without any specific information from the clinical units. It concludes that the use of separative methods for assaying glycated hemoglobin may lead to the detection of hemoglobin variants. It is also noted that the measurement of glycated hemoglobin with a reliable method is essential for establishing the diagnosis of β-thalassemia.

Introduction: Haemoglobin A1c (HbA1c) is considered to be the gold standard for the follow-up of glycaemic control in patients with diabetes mellitus and is also a diagnostic tool. Accordingly, reliable and efficient methods must be used for its quantification. Roche Diagnostics have recently adapted the Tina-quant® HbA1c Third Generation immunoassay on a fully dedicated analyser, the Cobas c513, which allows a high throughput of up to 400 samples per hour. The present article deals with the evaluation of the analytical performances of this system which has been recently introduced to the market. Materials and methods: Precision, comparison with two ion-exchange high-performance liquid chromatography (HPLC) methods (Variant II and D-100 systems, BioRad Laboratories) using Passing Bablok and Bland-Altman analyses, accuracy and interference of the most frequent haemoglobin (Hb) variants on HbA1c measurement were evaluated. Results: Precision was high, with coefficients of variation lower than 1.1% (HbA1c values expressed in National Glycohemoglobin Standardization Program units, 1.7% for values expressed in International Federation of Clinical Chemistry and Laboratory Medicine [IFCC] units). The comparison study showed similar results with the two HPLC systems. The analysis of samples with IFCC-assigned values showed high methodological accuracy. Finally, no interference of bilirubin, triglycerides and common Hb variants (Hb AC, AD, AE, AS) was observed. Conclusions: This evaluation showed that the analytical performance of the Cobas c513 analyser for HbA1c assay makes it suitable for a routine use in clinical chemistry laboratories. [ABSTRACT FROM AUTHOR]