Synthesis,Characterization, and in Vitro Stability of Chitosan-Methotrexate Conjugates

Pharmaceutical Research -     

Tunnelling of caudal epidural catheters in infants

The working conditions in the developing world necessitate the development of many adaptations and improvizations of accepted anaesthetic techniques to improve patient care. Subcutaneous tunnelling of caudally placed epidural catheters is one such improvization to prevent the soiling of the catheter by urine and faeces. This study compares the duration of retention of catheter in a group with tunnelled catheters with an untunnelled group. The absence of a catheter emerging through skin at the site of catheter insertion hastens healing thus prolonging the retention of catheter in the tunnelled group and soiling ceases to be a major problem.     

Tripartite synapses: glia, the unacknowledged partner.

According to the classical view of the nervous system, the numerically superior glial cells have inferior roles in that they provide an ideal environment for neuronal-cell function. However, there is a wave of new information suggesting that glia are intimately involved in the active control of neuronal activity and synaptic neurotransmission. Recent evidence shows that glia respond to neuronal activity with an elevation of their internal Ca2+ concentration, which triggers the release of chemical transmitters from glia themselves and, in turn, causes feedback regulation of neuronal activity and synaptic strength. In view of these new insights, this article suggests that perisynaptic Schwann cells and synaptically associated astrocytes should be viewed as integral modulatory elements of tripartite synapses.     

Glutamate‐dependent astrocyte modulation of synaptic transmission between cultured hippocampal neurons

The idea that astrocytes merely provide structural and trophic support for neurons has been challenged by the demonstration that astrocytes can regulate neuronal calcium levels. However, the physiological consequences of astrocyte–neuron signalling are unknown. Using mixed cultures of rat hippocampal astrocytes and neurons we have determined functional consequences of elevating astrocyte calcium levels on co-cultured neurons. Electrical or mechanical stimulation of astrocytes to increase their calcium level caused a glutamate-dependent slow inward current (SIC) in associated neurons. Microinjection of 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA) into astrocytes to prevent the stimulus-dependent increase in astrocyte calcium level, blocks the appearance of the neuronal SIC. Pharmacological manipulations indicate that this astrocyte-dependent SIC is mediated by extracellular glutamate acting on N-methyl-d -aspartate (NMDA) and non-NMDA glutamate receptors. Additionally, stimulation of astrocytes reduced the magnitude of action potential-evoked excitatory and inhibitory postsynaptic currents through the activation of metabotropic glutamate receptors. The demonstration that astrocytes modulate neuronal currents and synaptic transmission raises the possibility that astrocytes play a neuromodulatory role by controlling the extracellular level of glutamate.     

Anaesthetic management of a patient with adrenocortical tumour

Adrenocortical tumours in children are rare. They produce many changes in haemodynamics and blood chemistry due to hormones of the adrenal cortex. The details of perioperative management and the need for perioperative steroid supplementation are discussed.