Independent component analysis and clustering improve signal-to-noise ratio for statistical analysis of event-related potentials

OBJECTIVE: To evaluate the effectiveness of a new method of using Independent Component Analysis (ICA) and k-means clustering to increase the signal-to-noise ratio of Event-Related Potential (ERP) measurements while permitting standard statistical comparisons to be made despite the inter-subject variations characteristic of ICA. METHODS: Per-subject ICA results were used to create a channel pool, with unequal weights, that could be applied consistently across subjects. Signals derived from this and other pooling schemes, and from unpooled electrodes, were subjected to identical statistical analysis of the N170 own-face effect in a Joe/No Joe face recognition paradigm wherein participants monitored for a target face (Joe) presented amongst other unfamiliar faces and their own face. Results between the Joe, unfamiliar face and own face conditions were compared using Cohen's d statistic (square root of signal-to-noise ratio) to measure effect size. RESULTS: When the own-face condition was compared to the Joe and unfamiliar-face conditions, the channel map method increased effect size by a factor ranging from 1.2 to 2.2. These results stand in contrast to previous findings, where conventional pooling schemes failed to reveal an N170 effect to the own-face stimulus (Tanaka JW, Curran T, Porterfield A, Collins D. The activation of pre-existing and acquired face representations: the N250 ERP as an index of face familiarity. J Cogn Neurosci 2006;18:1488-97). Consistent with conventional pooling schemes, the channel map approach showed no reliable differences between the Joe and Unfamiliar face conditions, yielding a decrease in effect size ranging from 0.13 to 0.75. CONCLUSIONS: By increasing the signal-to-noise ratio in the measured waveforms, the channel pool method demonstrated an enhanced sensitivity to the neurophysiological response to own-face relative to other faces. SIGNIFICANCE: By overcoming the characteristic inter-subject variations of ICA, this work allows classic ERP analysis methods to exploit the improved signal-to-noise ratio obtainable with ICA.     

Combination anti-inflammatory therapy: synergism in rats of NSAIDs/corticosteroids with some herbal/animal products

A useful function of any complementary medicine is to supplement some of the benefits from other treatment modalities. In rats, extracts from Indian celery seed and the NZ green-lipped mussel are powerful nutraceuticals that (i) amplify the potency of salicylates and prednisone for treating pre-established chronic inflammation (arthritis, fibrosis) and (ii) reduce the steroid's gastrotoxic and lymphopenic side effects. Such combinations might also be useful for treating inflammatory components of (a) osteoarthritis caused by microcrystalline hydroxyapatite (BCP) and (b) pseudo-gout, associated with calcium pyrophosphate crystals; that are usually refractory to monotherapy.     

Brain uptake of radiolabeled N‐oleoyl‐dopamine in the rat

N‐acyl‐dopamines are a novel class of biologically active lipids that have recently been identified in the brain and have the potential to interact with neural signaling pathways. This study seeks to determine the ability of N‐oleoyl‐dopamine, a synthetic amide of oleic acid and dopamine, to cross the blood brain barrier. We determined the tissue content of radioactivity in selected brain regions, in a short‐run study design, following injections of [³H]N‐oleoyl‐dopamine (0.4 µCi) into the internal carotid artery in the rat. These results were compared with intracarotid injections of [³H]dopamine and with intravenous injections of both radiolabeled compounds. The level of radioactivity was determined using liquid scintillation and was expressed as the percentage of its total dose injected per gram of tissue. We found that the 15‐min brain uptake of radioactivity, with no distinct regional variations, amounted to about 6% following the intracarotid [³H]N‐oleoyl‐dopamine, which was a significant 3–4‐fold increase over that following similar administration of [³H]dopamine. Intravenous injections of [³H]N‐oleoyl‐dopamine gave a much smaller yield of radioactivity in brain tissue samples which was still severalfold greater than that for intravenous [³H]dopamine. Qualitative thin‐layered chromatography screening showed the presence of unchanged N‐oleoyl‐dopamine in the brain following injections. We conclude that N‐oleoyl‐dopamine has an appreciable ability to cross the blood‐brain barrier, which contrasts the limited transfer of dopamine alone. N‐oleoyl‐dopamine might exert physiological effects due to its known affinity for the central vanilloid receptors or to better satisfying the brain tissue demand for dopamine. The study suggests a potential pharmacological role for N‐oleoyl‐dopamine delivered exogenously in helping regulate the brain function. Drug Dev. Res. 60:217–224, 2003. © 2003 Wiley‐Liss, Inc.     

Auditory and visual semantic priming using different stimulus onset asynchronies: An event-related brain potential study

Semantic priming effects (behavioral and electrophysiological) were compared in the visual and auditory modalities across three stimulus onset asynchronies (SOAs; 0, 200, and 800 ms). When both prime and target were presented in the visual modality (the prime just to the left of a fixation point and the target to the right) there were N400 priming effects present across the three SOAs. However, the N400 in the 0-ms SOA condition extended longer in time (800 vs. 500 ms) than in the other SOAs. When both the prime and target were presented in the auditory modality (the prime to the right ear and the target to the left), the largest priming effects were found for the 800-ms SOA. Moreover, there was a relatively early priming effect present in the 0- and 800-ms SOA conditions but not in the 200-ms condition. The results are discussed in terms of modality differences in the time course of word comprehension processes.     

N－（4－乙氧苯基）苯甲酰胺类化合物的合成及抗炎、抗变态反应活性研究

Ｎ┐（４┐乙氧苯基）苯甲酰胺类化合物的合成及抗炎、抗变态反应活性研究周玉新１）党永红刘建飞２）徐颖刘百里（沈阳药科大学制药系，沈阳１１００１５）郑文义（东北第六制药厂，沈阳１１００４３）１９８１年，刘百里等〔１，２〕发现和研制的新药益肤酰胺，经药理实...     

N-acetylcysteine prophylaxis significantly reduces the risk of radiocontrast-induced nephropathy: comprehensive meta-analysis.

The objectives of this study was to assess the overall effect of N-acetylcysteine (NAC) in preventing radiocontrast-induced nephropathy (RCIN) using all available data in the literature. RCIN is associated with increased morbidity and mortality. Existing randomized trials of NAC are small and show inconsistent results. Prior meta-analyses do not include data from the most current studies. We used standard search protocols to identify all published articles and abstracts of prospective trials using NAC with fluid hydration compared to hydration alone in patients with chronic renal insufficiency undergoing contrast procedures. A rise in serum creatinine by 0.5 mg/dl or 25% above baseline at 48-72 hr after contrast exposure was used as the primary outcome. We identified 14 trials of NAC with 1,584 patients published as full-text articles. Using a random-effects model, the use of oral NAC resulted in a significant reduction in the risk for developing RCIN (RR = 0.57; 95% CI = 0.37-0.84; P = 0.01). This finding did not significantly change in a fixed-effect model (RR = 0.55; 95% CI = 0.42-0.73) or when the data were reanalyzed using only randomized trials in all forms (i.e., articles and abstracts; RR = 0.67; 95% CI = 0.47-0.95). We identified only one important difference between the positive and the negative studies: the cumulative exposure to contrast media (174 vs. 152 ml). Metaregression did not show a significant relationship between contrast volume and the RR of developing RCIN (P > 0.10). In the trials showing benefit for NAC, the treated patients' postprocedure creatinine unexpectedly decreased by 0.21 mg/dl (95% CI = 0.33-0.08). Prophylaxis with NAC significantly reduces the risk for RCIN. The reasons for improvement in serum creatinine in patients treated with NAC are unclear, but may include improved renal blood flow due to NAC and/or vigorous hydration.     

青年人群血清甲_3型流感抗体检测和流行株的抗原性分析

采集４５０例战士血清标本，分别用国家代表株甲３／济防／１５／９０（Ｈ３Ｎ２）和甲３／北京／３２／９２（Ｈ３Ｎ２）作血清血凝抑制抗体测定，青年对甲３型抗体阳性率为６０％～６７％，其ＧＭＴ为３４～４５。１９９４～１９９５年两年中在军营人群中分离到３株Ｈ３Ｎ２毒株流行株，分别应用国际、国家和地方代表株作抗原性分析，证明流行株与它们之间抗原性有明显差异。本文分离到的３株流行株均上送国家流感中心鉴定，证实为Ｈ３Ｎ２亚型毒株。     

Identification of N2 as a metabolite of acetylhydrazine in the rat

 In the pathogenesis of isoniazid-induced hepatic injury, cytochrome P450-dependent metabolic activation of the metabolite, acetylhydrazine (AcHz), is the crucial step. Exhalation of [¹⁴C]-carbon dioxide has previously been used to quantify indirectly this pathway. In contrast, according to the current concept of AcHz bioactivation, molecular nitrogen is produced directly, but has not yet been identified. Here, we measured [¹⁵N]-nitrogen and ¹⁴CO₂ exhalation, after the administration of [¹⁵N₂]-[¹⁴C]-AcHz, in rats. Laser magnetic resonance (LMR) spectroscopy, a new sensitive and specific technique for the measurement of ¹⁵N and ¹⁴N in gas samples, was used. To demonstrate the involvement of cytochrome P450, rats were treated with phenobarbital (PB) or PB + cobalt(II) chloride (CoCl₂) (n=3 in each group). Time-dependent ¹⁵N₂ exhalation differed significantly between treatment groups (p<0.001). At 240 min, cumulative exhalation of ¹⁵N was 1.92±0.43% (mean±SE) of the dose in the control group, 2.53±0.23% in the PB group, and 1.00±0.15% in the PB+CoCl₂ group (p<0.05 compared to controls, p<0.01 compared to PB). Cumulative exhalation of ¹⁴CO₂ in 24 h ranged from 15.1 to 21.9%, with no significant difference between treatment groups. In conclusion, N₂ is a metabolite of AcHz. N₂ formation reflects the cytochrome P450-mediated activation of AcHz and can be used as an index of this pathway. Generally, LMR spectroscopy is valuable for monitoring any N₂-liberating process in vivo. Received: 14 March 1995/Accepted: 15 August 1995     

Evolution of North American PVYNTN Strain Tu 660 from Local PVYN by Mutation rather than Recombination

A North American (NA) isolate of tobacco veinal necrotic strain of Potato virus Y (PVY^N) (N-Jg) and a NA isolate of potato tuber necrotic strain of Potato virus Y (PVY^NTN) (Tu 660) were tested for their phenotypes by inoculation to potato plants of three potato cultivars. Upon inoculation with Tu 660, tubers of the cultivars NE" BORDER="0">NorchipNE" BORDER="0"> and NE" BORDER="0">Ranger RussetNE" BORDER="0"> developed potato tuber necrotic ringspot disease (PTNRD) but not the tubers of NE" BORDER="0">Russet BurbankNE" BORDER="0">. N-Jg failed to induce PTNRD in the tested cultivars. The genomic RNAs of both strains were completely sequenced and analysed. High homology (98% and 99% identity on nucleotide and polyprotein, respectively) was found between Tu 660 and N-Jg. When polyproteins were compared with other isolates, high identity was observed between Tu 660 and an European (Eu) PVY^N-605 (98%) and with an Eu-PVY^NTN-H (96%). However, when individual mature proteins were compared, much lower identities (86.5–94%) were found between Tu 660 and PVY^NTN-H compared to 98–99.5% between Tu 660 and PVY^N-605 in the P3, 6K1 and CI regions. Further sequence analysis indicated that the PVY^NTN-H is a hybrid molecule of the genomic RNA recombination of PVY^O and Eu-PVY^N as shown by Glais et al. (Arch Virol 147, 363–378), whereas NA-PVY^NTN Tu 660 is free of recombination points. Phylogenetic analysis confirmed this observation, and suggested that, in light of high homology, the Tu 660 might have evolved from NA-PVY^N by mutations rather than the genome recombinations. The non-recombinant nature of NA-PVY^NTN Tu 660 strongly suggests that the recombinant structure of genome is not a necessary prerequisite for the PTNRD phenotype.