Guanine sulphinate is a major stable product of photochemical oxidation of DNA 6-thioguanine by UVA irradiation.

The DNA of patients taking the immunosuppressant and anticancer drugs azathioprine or 6-mercaptopurine contains 6-thioguanine (6-TG). The skin of these patients is selectively sensitive to ultraviolet A radiation (UVA) and they suffer an extremely high incidence of sunlight-induced skin cancer with long-term treatment. DNA 6-TG interacts with UVA to generate reactive oxygen species, which oxidize 6-TG to guanine sulphonate (G(SO3)).

NCX3 knockout mice exhibit increased hippocampal CA1 and CA2 neuronal damage compared to wild-type mice following global cerebral ischemia.

There is uncertainty as to whether the plasma membrane Na(+)/Ca(2+)exchanger (NCX) has a neuroprotective or neurodamaging role following cerebral ischemia. To address this issue we compared hippocampal neuronal injury in NCX3 knockout mice (Ncx3(-/-)) and wild-type mice (Ncx3(+/+)) following global cerebral ischemia. Using a bilateral common carotid artery occlusion (BCCAO) model of global ischemia we subjected NCX3 knockout and wild-type mice to 17 and 15 minutes of ischemia.

The role of the Na(+)/Ca(2+) exchanger (NCX) in neurons following ischaemia.

The Na(+)/Ca(2+) exchanger (NCX) is a bi-directional membrane ion transporter. Under normal conditions, the exchanger transports one calcium ion out of the cell and three sodium ions into the cell. This is known as the calcium exit, or "forward" mode.

Novel DNA lesions generated by the interaction between therapeutic thiopurines and UVA light.

The therapeutic effect of the thiopurines, 6-thioguanine (6-TG), 6-mercaptopurine, and its prodrug azathioprine, depends on the incorporation of 6-TG into cellular DNA. Unlike normal DNA bases, 6-TG absorbs UVA radiation, and UVA-mediated photochemical damage of DNA 6-TG has potentially harmful side effects. When free 6-TG is UVA irradiated in solution in the presence of molecular oxygen, reactive oxygen species are generated and 6-TG is oxidized to guanine-6-sulfonate (G(SO3)) and guanine-6-thioguanine in reactions involving singlet oxygen.

Leptomeningeal carcinomatosis: an unusual cause of sudden onset bilateral sensorineural hearing loss.

We report a 66-year-old woman who developed sudden-onset bilateral sensorineural deafness due to leptomeningeal carcinomatosis involving the vestibulocochlear nerves. The clinical and diagnostic features of leptomeningeal carcinomatosis are discussed.

Spinal cord ganglioglioma presenting as acute paraparesis.

A 17-year-old male presented with acute onset paraparesis in the lower limbs. Urinary retention was present and the patient required catheterisation. Clinical examination confirmed severe bilateral lower limb weakness and a sensory level at T8.

Functioning paraganglioma of the thoracic spine: case report.

Objective And Importance: Paragangliomas of the thoracic spine are rare. Previously described cases involved nonfunctioning tumors. This report documents the diagnosis and surgical treatment for a patient who presented with a functioning thoracic paraganglioma.

Enantioselection in peptide bond formation.

Selectivity in abiotic condensations of amino acids remains controversial and stereochemically little explored. We find that competitive activated couplings of N-acyl derivatives of glycine, alanine, valine, proline and phenylalanine with binary, ternary and quaternary mixtures of amides and esters of the same group of amino acids show little selectivity among the reactants, except with respect to configuration, where a consistent and significant preference for heterochiral outcomes, mostly > 80%, is observed. One possible explanation of this selectivity predicts a predisposition to homochiral coupling under conditions that would require the two carboxyl functions to be co-facial in the activated complex.