The immediate-early gene Arc is transcribed in neurons that are part of stable neural networks activated during spatial exploratory behaviors. Arc protein has been demonstrated to regulate AMPA-type glutamate receptor trafficking by recruiting endosomal pathways, suggesting a direct role in synaptic plasticity. The purpose of the present study is to examine the fidelity of Arc mRNA translation and the temporal dynamics of behaviorally induced Arc protein expression after rats explore a novel environment. These experiments reveal two waves of Arc protein expression after a single exploration session. In the initial wave, virtually all cells that express Arc mRNA in the hippocampus and parietal cortex also express Arc protein, indicating, at a cellular level, that mRNA transcription and translation are closely correlated from 30 min to 2 h in hippocampal CA and parietal neurons. A second wave of protein expression spans the interval from 8 to 24 h and is also remarkably specific to cells active in the original behavior-induced network. This second wave is detected in a subset of the original active network and displays the novel property that the proportions of Arc-positive neurons become correlated among regions at 24 h. This suggests that the second expression wave is driven by network activity, and the stabilization of circuits reflecting behavioral experience may occur in temporally discrete phases, as memories become consolidated. This is the first demonstration of network-selective translational events consequent to spatial behavior and suggests a role for immediate-early genes in circuitspecific, late-phase synaptic biology.

Active behavior, such as exploring a novel environment, induces the expression of the immediate-early gene Arc (activity-regulated cytoskeletal associated protein, or Arg 3.1) in many brain regions, including the hippocampus, neocortex, and striatum. Arc messenger ribonucleic acid and protein are localized in activated dendrites, and Arc protein is required for the maintenance of long-term potentiation and memory consolidation. Although previous evidence suggests that Arc is expressed in neurons, there is no direct demonstration that only neurons can express Arc. Furthermore, there is no characterization of the main neuronal types that express Arc. The data reported here show that behavior- or seizure-induced Arc expression in the hippocampus, primary somatosensory cortex, and dorsal striatum of rats colocalizes only with neuronal (NeuN-positive) and not with glial (GFAP-positive) cells. Furthermore, Arc was found exclusively in non-GABAergic alpha-CaMKII-positive hippocampal and neocortical neurons of rats that had explored a novel environment. Some GAD65/67-positive neurons in these regions were observed to express Arc, but only after a very strong stimulus (electroconvulsive seizure). In the dorsal striatum, spatial exploration induced Arc only in GABAergic and alpha-CaMKII-positive neurons. Combined, these results show that although a very strong stimulus (seizure) can induce Arc in a variety of neurons, behavior induces Arc in the CaMKII-positive principal neurons of the hippocampus, neocortex, and dorsal striatum. These results, coupled with recent in vitro findings of interactions between Arc and CaMKII, are consistent with the hypothesis that Arc and CaMKII act as plasticity partners to promote functional and/or structural synaptic modifications that accompany learning.

Purpose: Green tea consumption has been associated with decreased risk of certain types of cancers in humans. Induction of detoxification enzymes has been suggested as one of the biochemical mechanisms responsible for the cancer-preventive effect of green tea. We conducted this clinical study to determine the effect of repeated green tea polyphenol administration on a major group of detoxification enzymes, glutathione S-transferases (GST). Methods: A total of 42 healthy volunteers underwent a 4-week washout period by refraining from tea or tea-related products. At the end of the washout period, a fasting blood sample was collected, and plasma and lymphocytes were isolated for assessment of GST activity and level. Following the baseline evaluation, study participants underwent 4 weeks of green tea polyphenol intervention in the form of a standardized Polyphenon E preparation at a dose that contains 800 mg epigallocatechin gallate (EGCG) once a day. Polyphenon E was taken on an empty stomach to optimize the oral bioavailability of EGCG. Upon completion of the intervention, samples were collected for postintervention GST assessment. Results: Four weeks of Polyphenon E intervention enhanced the GST activity in blood lymphocytes from 30.7 F 12.2 to 35.1 F 14.3 nmol/min/mg protein, P = 0.058. Analysis based on baseline activity showed that a statistically significant increase (80%, P = 0.004) in GST activity was observed in individuals with baseline activity in the lowest tertile, whereas a statistically significant decrease (20%, P = 0.02) in GST activity was observed in the highest tertile. In addition, Polyphenon E intervention significantly increased the GST-P level in blood lymphocytes from 2,252.9 F 734.2 to 2,634.4 F 1,138.3 ng/mg protein, P = 0.035. Analysis based on baseline level showed that this increase was only significant (P = 0.003) in individuals with baseline level in the lowest tertile, with a mean increase of 80%. Repeated Polyphenon E administration had minimal effects on lymphocyte GST-M and plasma GST-A levels. There was a small but statistically significant decrease (8%, P = 0.003) in plasma GST-A levels in the highest tertile. Conclusions: We conclude that 4 weeks of Polyphenon E administration resulted in differential effects on GST activity and level based on baseline enzyme activity/level, with GST activity and GST-P level increased significantly in individuals with low baseline enzyme activity/level. This suggests that green tea polyphenol intervention may enhance the detoxification of carcinogens in individuals with low baseline detoxification capacity. (Cancer Epidemiol Biomarkers Prev 2007;16(8):1662 -6)

The study may help identify appropriate high-risk populations for interventions that attenuate oxidative damage and appropriate biomarkers for clinical studies in smokers.

Thrombotic thrombocytopenia purpura (TTP) is a hematological emergency that requires rapid assessment followed by prompt initiation of therapy due to high mortality associated with delayed treatment. TTP has many causes including heritable syndromes, ADAMTS13 deficiency, and drugs-related etiologies. Profound vitamin B12 deficiency can, in rare cases, mimic TTP in presentation, and since plasmapheresis can be of limited benefit, prompt diagnosis is necessary for accurate treatment with B12. Therefore, careful analysis of all clinical signs, symptoms, and labs must be assessed. We report a patient who presented with a diagnosis of TTP, and repeat assessment confirmed a diagnosis of sever vitamin B12 (B12) deficiency with pancytopenia who was appropriately treated with B12.