Indirect calorimetry: From bench to bedside

Accurate determination of energy expenditure (EE) is vitally important yet often neglected in clinical practice. Indirect calorimetry (IC) provides one of the most sensitive, accurate, and noninvasive measurements of EE in an individual. Over the last couple of decades, this technique has been applied to clinical circumstances such as acute illness and parenteral nutrition. Beyond assessing the nutritional needs, it has also shed light on various aspects of nutrient assimilation, thermogenesis, the energetics of physical exercise, and the pathogenesis of obesity and diabetes. However, because of little or no experience with IC provided during medical education, the benefits of IC are poorly appreciated. Newer technology, cost-effectiveness, and a better understanding of how to interpret measurements should lead to more frequent use of IC. This review focuses on the physicochemical background of IC, the various indications for use, techniques and instruments, potential pitfalls in measurement, and the recent advances in technology that has adapted the technique to long-term studies in humans

Super-enhancer associated core regulatory circuits mediate susceptibility to retinoic acid in neuroblastoma cells

Peer reviewed: TrueAcknowledgements: We gratefully thank Prof. Deborah Tweddle for providing the neuroblastoma cell lines. We thank Prof. Jason Carroll, and Shakhzada Ibragimova for helpful discussions. Finally, we thank Divinn Lal, Dr. Sathishkumar Ramaswamy, and Maha ELNaofal from Al Jalila Genomics Center for their help. We would like to acknowledge the support of the Mohammed Bin Rashid University of Medicine and Health Sciences and Al Jalila Foundation.Neuroblastoma is a pediatric tumour that accounts for more than 15% of cancer-related deaths in children. High-risk tumours are often difficult to treat, and patients’ survival chances are less than 50%. Retinoic acid treatment is part of the maintenance therapy given to neuroblastoma patients; however, not all tumours differentiate in response to retinoic acid. Within neuroblastoma tumors, two phenotypically distinct cell types have been identified based on their super-enhancer landscape and transcriptional core regulatory circuitries: adrenergic (ADRN) and mesenchymal (MES). We hypothesized that the distinct super-enhancers in these different tumour cells mediate differential response to retinoic acid. To this end, three different neuroblastoma cell lines, ADRN (MYCN amplified and non-amplified) and MES cells, were treated with retinoic acid, and changes in the super-enhancer landscape upon treatment and after subsequent removal of retinoic acid was studied. Using ChIP-seq for the active histone mark H3K27ac, paired with RNA-seq, we compared the super-enhancer landscape in cells that undergo neuronal differentiation in response to retinoic acid versus those that fail to differentiate and identified unique super-enhancers associated with neuronal differentiation. Among the ADRN cells that respond to treatment, MYCN-amplified cells remain differentiated upon removal of retinoic acid, whereas MYCN non-amplified cells revert to an undifferentiated state, allowing for the identification of super-enhancers responsible for maintaining differentiation. This study identifies key super-enhancers that are crucial for retinoic acid-mediated differentiation.</jats:p

Nutritional Intake in Low Body Mass Index (BMI) Males with Type 1 Diabetes and Fibrocalcific Pancreatic Diabetes: What are the Unmet Needs? A Cross-Sectional Study from a South Indian Tertiary Care Hospital

Introduction: There is paucity of data on the nutritional intake in low Body Mass Index (BMI) Asian Indians with diabetes. Aim: To study the difference in the nutrient intake pattern in low-BMI Type 1 Diabetes Mellitus (T1DM) and Fibrocalcific Pancreatic Diabetes (FCPD) patients. Materials and Methods: This cross-sectional study consisted of T1DM (n=40) and FCPD (n=20) male patients with similar BMI. Nutritional data was collected using the 24 hour recall method and food diaries. Fasting blood samples were analysed for lipid profile, serum creatinine, glycosylated haemoglobin, albumin, calcium and vitamin D. Stool samples were analysed for pancreatic elastase. Percentage analysis, Independent sample t-test and Pearson coefficient correlation were used to analyse the data. A p-value<0.05 was considered as statistically significant. Results: The FCPD patients, on biochemical analysis, had significantly lower vitamin D levels compared to the T1DM group (p=0.035). However, haemoglobin, triglycerides, low density lipoproteins, creatinine, albumin and calcium were similar between the groups. In the nutrient data, FCPD patients had a significant higher intake of fat (p=0.039), fibre (p<0.001), calcium (p=0.047), phosphorous (p=0.035), and niacin (p=0.001) and calories from fat (p=0.047). The T1DM group had a significantly higher intake of thiamine (p=0.047) and carbohydrates (p=0.014). Conclusion: T1DM and FCPD groups have similar dietary pattern deficit in fibre, calories, macronutrients and micronutrients. Malabsorption and poor glycaemic control in FCPD patients can be attributed to a higher dietary fat intake. A balanced diet can ensure better glycaemic control

Rv0474 is a copper-responsive transcriptional regulator that negatively regulates expression of RNA polymerase subunit in Mycobacterium tuberculosis

We characterize Rv0474, a putative transcriptional regulatory protein of Mycobacterium tuberculosis, which is found to function as a copper-responsive transcriptional regulator at toxic levels of copper. It is an autorepressor, but at elevated levels (10-250 m) of copper ions the repression is relieved resulting in an increase in Rv0474 expression. Copper-bound Rv0474 is recruited to the rpoB promoter leading to its repression resulting in the growth arrest of the bacterium. Mutational analysis showed that the helix-turn-helix and leucine zipper domains of Rv0474 are essential for its binding to Rv0474 and rpoB promoters, respectively. The mechanism of Rv0474-mediated rpoB regulation seems to be operational only in pathogenic mycobacteria that can persist inside the host

Hypothetical protein Rv3423.1 of Mycobacterium tuberculosis is a histone acetyltransferase

We isolated an 8 kDa mycobacterial hypothetical protein, Rv3423.1, from the chromatin of human macrophages infected with Mycobacterium tuberculosis H37Rv. Bioinformatics predictions followed by in vitro biochemical assays with purified recombinant protein showed that Rv3423.1 is a novel histone acetyltransferase that acetylates histone H3 at the K9/K14 positions. Transient transfection of macrophages containing GFP-tagged histone H1 with RFP-tagged Rv3423.1 revealed that the protein co-localizes with the chromatin in the nucleus. Co-immunoprecipitation assays confirmed that the Rv3423.1-histone interaction is specific. Rv3423.1 protein was detected in the culture filtrate of virulent but not avirulent M. tuberculosis. Infection of macrophages with recombinant Mycobacterium smegmatis constitutively expressing Rv3423.1 resulted in a significant increase in the number of intracellular bacteria. However, the protein did not seem to offer any growth advantage to free-living recombinant M. smegmatis. It is highly likely that, by binding to the host chromatin, this histone acetyltransferase from M. tuberculosis may manipulate the expression of host genes involved in anti-inflammatory responses to evade clearance and to survive in the intracellular environment