Cancer stem cell metabolism: A potential target for cancer therapy

© 2016 The Author(s). Cancer Stem cells (CSCs) are a unipotent cell population present within the tumour cell mass. CSCs are known to be highly chemo-resistant, and in recent years, they have gained intense interest as key tumour initiating cells that may also play an integral role in tumour recurrence following chemotherapy. Cancer cells have the ability to alter their metabolism in order to fulfil bio-energetic and biosynthetic requirements. They are largely dependent on aerobic glycolysis for their energy production and also are associated with increased fatty acid synthesis and increased rates of glutamine utilisation. Emerging evidence has shown that therapeutic resistance to cancer treatment may arise due to dysregulation in glucose metabolism, fatty acid synthesis, and glutaminolysis. To propagate their lethal effects and maintain survival, tumour cells alter their metabolic requirements to ensure optimal nutrient use for their survival, evasion from host immune attack, and proliferation. It is now evident that cancer cells metabolise glutamine to grow rapidly because it provides the metabolic stimulus for required energy and precursors for synthesis of proteins, lipids, and nucleic acids. It can also regulate the activities of some of the signalling pathways that control the proliferation of cancer cells. This review describes the key metabolic pathways required by CSCs to maintain a survival advantage and highlights how a combined approach of targeting cellular metabolism in conjunction with the use of chemotherapeutic drugs may provide a promising strategy to overcome therapeutic resistance and therefore aid in cancer therapy

Suppression of thermo-acoustic instability using air injection in horizontal Rijke tube

The thermo-acoustic instability arising out of coupling between the pressure fluctuation and the unsteady heat release, when grows sufficiently, is known to cause serious structural damage thereby reducing the life span of systems having combustor for example, jet engines, gas turbines and industrial burners. The present work involves experimental study of thermo-acoustic instabilities occurring in a Rijke tube and their suppression by means of diverting a very small fraction of the incoming air flow in the form of radial injection from the wall of the tube through micro jets. A horizontal quartz tube with pre-mixed burner is used as the test model of Rijke tube. The coefficient Rayleigh Index (RI) is estimated from simultaneous measurement of chemiluminescence using a PMT and pressure in the plane of burner head. Experiments were carried out at the equivalence ratio of phi = 1 for a range of the burner position inside the tube, velocity of micro jets, and total mass flow rate through the tube. The control technique of micro jets was found to completely suppress the thermo-acoustics in a range of jet velocity depending on the burner position and the total air mass flow rate. For complete suppression of the thermos-acoustics, the phase difference between the pressure and chemiluminescence waves was found to significantly increase and the RI was found to reduce to nearly zero. In such case, the flame luminescence was observed to significantly reduce. The proposed technique of air injection into the flame through radial micro jets is simple yet very effective in controlling the thermos-acoustic instability. (C) 2016 Energy Institute. Published by Elsevier Ltd. All rights reserved

Experiments on heat content inside a Rijke tube with suppression of thermo-acoustics instability

The present work describes the occurrence of thermo-acoustic instability inside a horizontal Rijke tube and its suppression using an open loop active control technique. The Rijke tube is provided with a co-axial pre-mixed gas burner as the source of heat, which could be placed at any desired position. Radial injection of air (less than 3% of the total mass flow) through micro-jets into the flame is used as a control technique to suppress the thermo-acoustic instability. The rise in heat content inside the Rijke tube, estimated from the temperature mapping, clearly shows reduction in the heat loss as a result of complete suppression of the thermo-acoustic instability. However, the stability achieved passively by means of a slight shift in the burner position does not result in any change in the heat content. There is a visible change in the appearance of the burner flame when the above two methods are used to suppress the thermo-acoustic instability. The flame is seen to significantly shrink in length and spread radially when the control technique was applied. The flame dynamics is believed to determine the heat loss and hence the heat content inside the Rijke tube