A number of studies have indicated that antagonists of the N-methyl-d-aspartate (NMDA) subtypes of glutamate receptors can cause schizophrenia-like symptoms in healthy individuals and exacerbate symptoms in individuals with schizophrenia. These findings have led to the glutamate hypothesis of schizophrenia. Here we review the evidence for this hypothesis in postmortem studies of brain tissue from individuals affected by schizophrenia, summarizing studies of glutamate neuron morphology, of expression of glutamate receptors and transporters, and of the synthesizing and metabolizing enzymes for glutamate and its co-agonists. We found consistent evidence of morphological alterations of dendrites of glutamatergic neurons in the cerebral cortex of subjects with schizophrenia and of reduced levels of the axon bouton marker synaptophysin. There were no consistent alterations of mRNA expression of glutamate receptors, although there has been limited study of the corresponding proteins. Studies of the glutamate metabolic pathway have been limited, although there is some evidence that excitatory amino acid transporter-2, glutamine synthetase, and glutaminase have altered expression in schizophrenia. Future studies would benefit from additional direct examination of glutamatergic proteins. Further advances, such as selective testing of synaptic microdomains, cortical layers, and neuronal subtypes, may also be required to elucidate the nature of glutamate signaling impairments in schizophrenia.

Nutrient pollution is of worldwide environmental and health concerns due to extensive use of nitrogen fertilizers and release of livestock waste, which induces nitrite compounds in aquatic systems. Here-in a surface-enhanced Raman scattering (SERS) sensor is developed for nitrite detection based on coupling between the plasmonic gold nanostars and the silver nanopyramid array. When nitrite is present in the assay, an azo group is formed between the 1-naphthylamine-functionalized silver nanopyramids and the 4-aminothiophenol-functionalized gold nanostars. This not only generates the SERS spectral finger-print for selective detection, but also creates “hot spots” at the gap between the Au nanostars and the Ag nanopyramids where the azo group is located, amplifying SERS signals remarkably. Finite-difference time-domain (FDTD) simulation shows a SERS enhancement factor of 4×1010 at the “hot spots”. As a result, the SERS sensor achieves a limit of detection of 0.6 pg/mL toward nitrite in water, and enables nitrite detection in real-world river water samples. In addition, this sensor eliminates the use of any Raman reporter and any expensive molecular recognition probe such as antibody and aptamer. This highly sensitive, selective and inexpensive SERS sensor has unique advantages over colorimetric, electrochemical and fluorescent devices for small molecule detection.

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Significant increases in physiological response at some doses suggest that users were exposed to pharmacologically active doses of nicotine. The lack of reliable subjective effects may be the product of the dosing regimen or the relatively small sample size. Findings highlight the need for identification of doses of snus that may promote abuse among naïve users.