Auditory event-related potentials during stage 2 NREM sleep in humans

SUMMARY  Event-related potential (ERP) recordings were used to investigate the nature of auditory stimulus evaluation during stage 2 sleep. Frequent and rare stimuli, differing in intensity and frequency, were presented to six adult subjects while awake and asleep. The latency and voltage distribution of one of the long-latency components evoked during sleep resembled the P3 component evoked while awake. However, it was attenuated in voltage and superimposed on N3, a large late negative component, most probably the slow potential of the K complex. The identification of a P3-like potential during sleep suggests that the P3 potential is not solely a marker of active cognitive processes, but contains a small component which reflects automatic, pre-attentive evaluation of deviant stimuli.     

Purification of P-selectin (CD62P) from human platelets

Summary A method is described for immunoaffinity purification of P-selectin from outdated human platelets.     

Second Thoughts: Multiple P300s Elicited by a Single Stimulus

In a previous report (Johnson & Donchin, 1978), we manipulated the discriminability of tone pairs that delivered feedback information in a time-estimation paradigm. As in other experiments using feedback stimuli, the event-related potentials elicited by these stimuli did not return to baseline in the 800-ms poststimulus interval. Since we were interested in this “Slow Wave'’activity, the poststimulus interval was lengthened to 1500 ms. Averages revealed that a second positive peak was present for some of the individual subjects. To investigate this activity further, the filtered singletrial waveforms were inspected visually. These data were characterized by the presence of one, and occasionally two, positive peaks, with highly variable latencies, following the P300. These peaks were indistinguishable in frequency and general appearance from the P300s elicited by the feedback stimuli. After latency adjusting the waveforms on the peak of the second positive wave, amplitude and latency were quantified. Whereas P300 amplitude was directly related to stimulus discriminability and positive feedback elicited larger P300s than negative feedback, the amplitude of the second positive wave was constant across levels of discriminability and the same for both types of feedback. In contrast, the latencies of both waves were inversely related to stimulus discriminability and shorter following positive feedback than negative feedback. Evidence is presented to support our contention that these additional positive peaks represent P300 activity. The data are discussed in terms of what these multiple P300s reveal about human information processing.     

血清淀粉样P成分的DNA结合特性

目的 检测血清淀粉样P成分(SAP)与不同DNA的结合活性并研究SAP与DNA的结合是否有利于此类抗原的清除，探讨它在SLE发生发展中的作用及意义。方法 用亲和层析和凝胶过滤方法自小鼠和人血清中纯化SAP，分别提取来自细菌、质粒、酵母、小鼠淋巴细胞等不同DNA，用DOT-EIA方法检测SAP与它们的结合活性，用巨噬细胞吞噬实验观察SAP与DNA结合后对DNA清除的影响。结果 人和小鼠SAP均与细菌DNA结合最强，其次为质粒、酵母DNA，与淋巴细胞DNA和小牛胸腺DNA的结合较弱，与单链λDNA结合最弱；与来源于活化状态小鼠淋巴细胞DNA的结合力高于非活化状态；SAP与活化淋巴细胞DNA结合后可促进巨噬细胞对DNA的吞噬。结论 SAP与不同DNA结合活性各异。     

Comparison of hprt and lacI mutant frequency with DNA adduct formation in N-hydroxy-2-acetylaminofluorene-treated Big Blue rats

N-Hydroxy-2-acetylaminofluorene (N-OH-AAF) is the proximate carcinogenic metabolite of the powerful rat liver carcinogen 2-acetylaminofluorene. In this study, transgenic Big Blue(R) rats were used to examine the relationship between in vivo mutagenicity and DNA adduct formation by N-OH-AAF in the target liver compared with that in nontarget tissues. Male rats were given one, two, or four doses of 25 mg N-OH-AAF/kg body weight by i.p. injection at 4-day intervals, and groups of treated and control rats were euthanized up to 10 weeks after beginning the dosing. Mutant frequencies were measured in the spleen lymphocyte hprt gene, and lacI mutant frequencies were determined in the liver and spleen lymphocytes. At 6 weeks after beginning the dosing, the hprt mutant frequency in spleen lymphocytes from the four-dose group was 16.5 x 10(-6) compared with 3.2 x 10(-6) in control animals. Also at 6 weeks, rats given one, two, or four doses of N-OH-AAF had lacI mutant frequencies in the liver of 97.6, 155.6, and 406.8 x 10(-6), respectively, compared with a control frequency of 25.7 x 10(-6); rats given four doses had lacI mutant frequencies in spleen lymphocytes of 55.8 x 10(-6) compared with a control frequency of 20.4 x 10(-6). Additional rats were evaluated for DNA adduct formation in the liver, spleen lymphocytes, and bone marrow by (32)P-postlabeling. Adduct analysis was conducted 1 day after one, two, and four treatments with N-OH-AAF, 5 days after one treatment, and 9 days after two treatments. N-(Deoxyguanosin-8-yl)-2-aminofluorene was the major DNA adduct identified in all the tissues examined. Adduct concentrations increased with total dose to maximum values in samples taken 1 day after two doses, and remained essentially the same after four doses. In samples taken after four doses, adduct levels were 103, 28, and 7 fmol/microg of DNA in liver, spleen lymphocytes, and bone marrow, respectively. The results indicate that the extent of both DNA adduct formation and mutant induction correlates with the organ specificity for N-OH-AAF carcinogenesis in the rat. Environ. Mol. Mutagen. 37:195-202, 2001. Published 2001 Wiley-Liss, Inc.     

Effects of aging on the novelty P3 during attend and ignore oddball tasks

The effects of attention were assessed on novelty P3 amplitude and scalp distribution elicited by environmental sounds in young and elderly volunteers who participated in either actively attended or ignored oddball conditions. For the young, novelty P3 amplitude decreased with time on task during both attend and ignore sequences. Amplitude decrements were greatest at frontal sites during the attend condition, but at all sites during the ignore condition. A reliable amplitude decrement was not observed for the elderly in either the attend or ignore oddball series. The data suggest that attention differentially activates multiple generators that contribute to scalp-recorded novelty P3 activity. The lack of novelty P3 habituation seen in the elderly is consistent with changes in frontal lobe function as age increases.     

汉族男女七对显、隐性性状及基因频率的研究

目的探讨汉族男女在正常性状表现及基因频率的差异.方法调查湖南境内汉族男女7对正常遗传性状,并用Hardy-Weinberg定律和分离定律计算男女每一性状的基因频率.结果眼睑、拇指末关节的性状在汉族男女之间差异较大,而卷舌、耳垂、前额发际、发式、发旋无明显差异.结论同一民族不同性别在性状表现及基因频率方面存在差异,为中国人群体遗传学研究提供资料.     

Repeated immunization with plasmid DNA formulated in poly(lactide-co-glycolide) microparticles is well tolerated and stimulates durable T cell responses to the tumor-associated antigen cytochrome P450 1B1

Injection of microparticle-encapsulated DNA elicits immune responses to plasmid-encoded antigens in mice and humans. Cytochrome P450 CYP1B1 (CYP1B1) is a member of the CYP1 P450 enzyme family that is overexpressed in a variety of solid tumors. The work described herein was performed to study the kinetics of stimulating T cell responsiveness with an encapsulated DNA encoding CYP1B1 and provides support for the clinical development of this formulation. Immunization of HLA-A2/Kb transgenic mice with human CYP1B1 encoding plasmid DNA formulated in poly(lactide-co-glycolide) (PLG) microparticles elicits CD8+ T cells that respond to human CYP1B1-positive target cells. The duration of the immune response, the effect on the immune response of multiple injections, and the safety of repeated injections were studied. These results show that the PLG-encapsulated DNA therapeutic elicits durable immune responses to CYP1B1, the responses are dependent on repeat immunization, and that the formulation is well tolerated.     

Effect of Temperature on Guinea Pig Urinary Bladder Contraction Mediated via P2X-Receptors

In vitro experiments showed that P2X-receptor agonist ,-methylene-ATP and electrical field stimulation in the presence of muscarinic and -adrenoreceptors blockers induced contractile responses of isolated guinea pig bladder, which were more pronounced at 30°C than at 37°C or 42°C. P2X-receptor antagonist pyridoxal-6-phosphate-2',4'-disulfonic acid, produced a more potent inhibitory effect on contractions induced by electrical field stimulation at 30°C in comparison with that at 37°C or 42°C, while the contractions induced by ,-methylene-ATP were similarly suppressed at all examined temperatures.