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In search of a role for the heavy chain of tetanus toxin in poisoning, its actions on natural and artificial membranes have been assessed. The heavy chain increases the permeability of synaptosomes to lactate dehydrogenase and potassium ions, and promotes the outward shift of the lipophilic cation tetraphenylphosphonium which is a particularly sensitive indicator for depolarization. Independent of the assay system the potency of the heavy chain is high, i.e. in the range of about 1 nM, whereas its efficacy is low. Its potency is decreased by the addition of the light chain and by treatment of the synaptosomes with the C-terminal fragment C of the heavy chain, but not with its N-terminal fragment beta 2. Single- or two-chain toxin itself is inactive, and so are the light chain or the two heavy chain fragments beta 2 and C. Liposomes were made from phosphatidylcholine and phosphatidylserine or gangliosides and loaded with calcein. At pH 6 the outflow of calcein is promoted in the order heavy chain greater than toxin much greater than fragment beta 2, and the action of toxin is promoted by ganglioside. At pH 5, fragment beta 2 is nearly as active as the heavy chain and more potent than the toxin. The heavy chain, but neither of the fragments, is strongly adsorbed in hydrophobic interaction chromatography and caused aggregation of polystyrene-divinylbenzene beads. Evidence for polymerization of heavy chains is lacking in zonal centrifugation. It is concluded that both domains of the heavy chain co-operate to exert the membranal events described, and that the heavy chain is partially hidden by the light chain in the complete toxin molecule. 相似文献
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OBJECTIVE: The purpose of this study was to illustrate the use of latent class analysis to examine change in behavior over time. Patterns of heavy drinking from ages 18 to 30 were explored in a national sample; the relationship between college enrollment and pathways of heavy drinking, particularly those leading to adult heavy drinking, was explored. METHOD: Latent class analysis for repeated measures is used to estimate common pathways through a stage-sequential process. Common patterns of development in a categorical variable (presence or absence of heavy drinking) are estimated and college enrollment is a grouping variable. Data were from the National Longitudinal Survey of Youth (N=1,265). RESULTS: Eight patterns of heavy drinking were identified: no heavy drinking (53.7%); young adulthood only (3.7%); young adulthood and adulthood (3.7%); college age only (2.6%); college age, young adulthood, and adulthood (8.7%); high school and college age (4.4%); high school, college age, and young adulthood (6.3%); and persistent heavy drinking (16.9%). CONCLUSIONS: We found no evidence that prevalence of heavy drinking for those enrolled in college exceeds the prevalence for those not enrolled at any of the four developmental periods studied. In fact, there is some evidence that being enrolled in college appears to be a protective factor for young adult and adult heavy drinking. College-enrolled individuals more often show a pattern characterized by heavy drinking during college ages only, with no heavy drinking prior to and after the college years, whereas nonenrolled individuals not drinking heavily during high school or college ages are at increased risk for adult heavy drinking. 相似文献
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目的测定4种牛黄解毒片中酸可溶性重金属和总重金属的含量。方法以人工胃液对制剂进行样品前处理后,采用电感耦合等离子体原子发射光谱法(ICP-AES)分别测定上述4种成药中酸可溶性重金属和总重金属的含量。结果 4种成药中总金属含量均超过国家行业标准限量及美国药典,而酸可溶性重金属含量均低于其总重金属含量,基本符合或接近国家标准。结论酸可溶性重金属含量限度可作为牛黄解毒片及含重金属矿物中成药的质控指标之一。 相似文献
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Depressive symptoms are a vulnerability factor for heavy episodic drinking: A short-term,four-wave longitudinal study of undergraduate women 总被引:1,自引:0,他引:1
Aislin R. Mushquash Sherry H. Stewart Simon B. Sherry Dayna L. Sherry Christopher J. Mushquash Anna L. MacKinnon 《Addictive behaviors》2013
Heavy episodic drinking is increasingly common among undergraduate women. Cross-sectional research suggests that depressive symptoms and heavy episodic drinking are related. Nonetheless, surprisingly little is known about whether depressive symptoms are an antecedent of heavy episodic drinking, a consequence of heavy episodic drinking, or both. Such knowledge is essential to the accurate conceptualization of heavy episodic drinking, depressive symptoms, and their interrelations. In the present short-term longitudinal study, depressive symptoms and heavy episodic drinking were proposed to reciprocally influence each other over time, with depressive symptoms predicting changes in heavy episodic drinking over 1 week and vice versa. This reciprocal relations model was tested in 200 undergraduate women using a 4-wave, 4-week longitudinal design. Structural equation modeling was used to conduct cross-lagged analyses testing reciprocal relations between depressive symptoms and heavy episodic drinking. Consistent with hypotheses, both depressive symptoms and heavy episodic drinking were temporally stable, and depressive symptoms predicted changes in heavy episodic drinking over 1 week. Contrary to hypotheses, heavy episodic drinking did not predict changes in depressive symptoms over 1 week. Results are consistent with a vulnerability model suggesting depressive symptoms leave undergraduate women vulnerable to heavy episodic drinking. For undergraduate women who are struggling with feelings of sadness, worthlessness, and hopelessness, heavy episodic drinking may provide a temporary yet maladaptive means of avoiding or alleviating depressive symptoms. 相似文献
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Examinations of heavy drinking and dating violence have typically focused on either female victimization or male perpetration; yet recent findings indicate that mutual aggression is the most common pattern of dating violence. The current study investigated the relation between heavy drinking and dating violence for both men and women. Participants (N = 2247) completed surveys that assessed their heavy drinking and dating violence frequency across the first three years of college. Findings indicated that heavy drinking and dating violence were both relatively stable across time for men and women, but the relation between heavy drinking and dating violence differed by gender. For men, heavy drinking and dating violence were concurrently associated during their freshman year (Year 1), whereas for women heavy drinking during their sophomore year (Year 2) predicted dating violence in their junior year (Year 3). In addition to providing educational material on healthy relationships and conflict resolution techniques, intervention efforts should target both heavy drinking and dating violence for men during or prior to their freshman year of college, whereas women may primarily benefit from efforts to reduce their heavy drinking. 相似文献
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Hisashi Nakayama Tadatoshi Takayama Akihiro Hemmi 《Nihon Arukōru Yakubutsu Igakkai zasshi》2006,41(5):419-423
The adequate treatment for patients with thrombocytopenia, encephalopathy, ascites and esophagogastric varices due to portal hypertension are very important. This review explains the relations between heavy drinkers and symptoms of portal hypertension, especially with regard to the form of esophageal varices. Between heavy drinker and non-heavy drinker, there was no significant differences for form, color and red color sign of varices. In heavy drinker, the ratio of strong red color sign might be higher than non-heavy drinker. Value of portal pressure in heavy drinker might be higher. These results can bring sudden variceal bleeding in heavy drinkers. 相似文献
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LM Squeglia C Pulido RR Wetherill J Jacobus GG Brown SF Tapert 《Journal of studies on alcohol and drugs》2012,73(5):749-760
ABSTRACT. Objective: Many adolescents engage in heavy alcohol use. The aim of this study was to disentangle whether brain abnormalities seen in adolescent heavy drinkers are a consequence of heavy drinking, a preexisting risk factor for initiation of alcohol use, or both. Method: Study 1 used cross-sectional functional magnetic resonance imaging (fMRI) visual working-memory (VWM) data from 15- to 19-year-olds (20 heavy drinkers, 20 controls) to identify brain regions affected by heavy adolescent alcohol use. Study 2 used longitudinal fMRI VWM data from 12- to 16-year-olds imaged before the onset of drinking and imaged again on the same scanner approximately 3 years later. Those who had transitioned into heavy drinking (n = 20) were matched to continuous nondrinkers (n = 20) on baseline alcohol risk and developmental factors (N = 40; 80 scans). Results: Study 1 found that heavy drinkers exhibited more frontal and parietal but less occipital activation than controls, defining the regions of interest for Study 2. In Study 2, adolescents who later transitioned into heavy drinking showed less fMRI response contrast at baseline than continuous nondrinkers, which increased after the onset of heavy drinking, in frontal (1,431 μL, p = .003; η22 = .19) and parietal (810 μL, p = .005; η22= .23) regions, as in Study 1. Lower baseline activation in the frontal and parietal regions predicted subsequent substance use, more so than commonly observed predictors of youth drinking (p < .05). Conclusions: Adolescents who initiated heavy drinking showed different brain activation before the onset of drinking, then less efficient information processing after high-dose alcohol use started. This suggests neural response patterns that could be risk factors for future substance use and also supports prior neuropsychological reports indicating that initiating heavy episodic drinking in adolescence may be followed by subtle alterations in brain functioning. (J. Stud. Alcohol Drugs, 73, 749-760, 2012). 相似文献
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OBJECTIVE: This study examined racial/ethnic differences in the association between college attendance and heavy alcohol use and factors that may underlie this relationship. METHOD: Interview data collected from 12,993 young adults who participated in the National Longitudinal Study of Adolescent Health were analyzed to determine if 4- or 2-year college status is differentially associated with heavy alcohol use for five racial/ethnic groups (white, black, Hispanic, Asian, Other) and to assess the explanatory value of selected social and psychological factors. RESULTS: Four-year college status was positively associated with heavy alcohol use among white young adults but inversely related to heavy drinking among blacks and Asians. Two-year college status also was inversely associated with heavy drinking among blacks, Hispanics and Others. Among whites, the association between 4-year college attendance and heavy drinking was partially explained by living away from parents, friends' heavy drinking and time socializing with friends. Among blacks, the inverse relationship between college attendance and heavy alcohol use was partially explained by lower levels of friends' heavy drinking, depression and delinquency. Friends' heavy drinking also partially explained observed relationships between college attendance and heavy drinking among Asians and Others. CONCLUSIONS: Four-year college attendance increases the likelihood of heavy alcohol use among white young adults but may decrease the likelihood of heavy drinking among blacks and Asians. Two-year college attendance also may reduce the risk for heavy drinking among blacks, Hispanics and young adults who are Native American or multi-ethnic. Social and psychological factors partly explain these relationships and also differ for racial/ethnic groups. 相似文献
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中药中重金属和残留农药去除方法研究进展 总被引:2,自引:0,他引:2
目的为选择中药中重金属和残留农药的去除方法提供依据。方法根据近年的23篇文献,从去除中药中重金属技术及去除中药中残留农药技术两个方面进行综述。结果去除重金属的方法有吸附色谱分离法、吸附澄清法、超临界CO2配合萃取法;去除残留农药的方法有水洗法、炮制法、超临界CO2流体萃取法。结论色谱分离技术为很有前途的去除重金属的处理技术;超临界CO2流体萃取法对于去除中药中重金属和残留农药效果较好。 相似文献
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西洋参等8种中药的重金属检测 总被引:6,自引:0,他引:6
目的建立中药中重金属含量测定方法,考察市售药材的重金属含量。方法用紫外分光光度法测定西洋参、人参、枸杞、甘草、川贝母、丹参6种植物药及蜈蚣、僵蚕2种动物药中重金属的舍量。结果在对照品重金属铅质量浓度为0~0.50μg/mL范围内与吸光度线性关系良好,r=0.9977,平均加样回收率为99.49%,RSD:1.09%(n=6);西洋参、人参、枸杞、甘草、川贝母、丹参的重金属含量分别为26.13%,28.96%,26.99%,29.98%,26.63%,28.06%,而蜈蚣、僵蚕的重金属偏高,分别为47.62%和59.24%。结论紫外分光光度法简便、灵敏,可用于中药重金属含量的检测。 相似文献
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The purpose of this study was to assess the effects of modeling as a determinant of alcohol consumption by both male and female subjects who were classified as either light or heavy social drinkers. College student subjects (N = 64) were assigned to eight groups in a 2 x 2 x 2 factorial design. Male and female subjects, half of whom were classified as light drinkers and half heavy drinkers, were exposed either to a light drinking or heavy drinking model of the same sex during the course of a wine-tasting task. The taste-rating task served as an unobtrusive measure of alcohol consumption. The modeling factor was a significant determinant of drinking in this task: subjects exposed to the heavy drinking model drank more than subjects who observed the light drinking model. While all subjects drank a minimal amount in the light drinking model condition, an interaction effect was obtained in the heavy drinking model condition: heavy social drinkers, particularly the male subjects, drank significantly more wine in the presence of the heavy drinking model than did the light social drinkers. The results were discussed in terms of their implications for understanding the social determinants of drinking behavior in young adults. 相似文献
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OBJECTIVE: This study examined racial differences in the relationship between postsecondary education (PSE) and heavy drinking among young adults who participated in the 1998 National Household Survey on Drug Abuse. METHOD: In-home survey data collected from 6,374 18-25 year olds were analyzed to examine black-white differences in the relationship between PSE and past-month heavy drinking (five or more consecutive alcoholic beverages). Logistic regression analyses were conducted to examine the interactive effect of PSE and race on heavy drinking, and the degree to which selected psychosocial risk and protective factors help to explain the differential association between PSE and heavy drinking. RESULTS: The prevalence of past-month heavy drinking was significantly higher among whites with at least some PSE than whites without any PSE (41% vs 30%/6), whereas no differences in past-month heavy drinking were observed among blacks who did and did not have at least some PSE (15% vs 16%). This differential relationship persisted when early initiation of alcohol use and demographic characteristics were adjusted for. The effect of PSE on heavy drinking among whites was substantially reduced by controlling for perceived drinking among friends, friends' social support and subjects' propensity for risk taking or sensation seeking. PSE was inversely, although not significantly, associated with heavy drinking among blacks, after adjusting for early alcohol use and demographic characteristics. This inverse relationship was no longer present after controlling for psychosocial factors (e.g., religiosity, perceived harm of heavy drinking) that were associated with PSE and heavy drinking among blacks. CONCLUSIONS: The apparent effect of college attendance on heavy drinking among young adults is driven by the fact that the majority of young adults who attend college are white. College attendance does not appear to increase the likelihood of heavy drinking among black young adults. Additional research with longitudinal data is needed to better understand how the college environment affects alcohol use among whites, and whether blacks who attend predominantly white colleges are more likely to drink heavily than those who attend traditionally black colleges. 相似文献
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Although rape and sexual victimization experiences have been hypothesized to contribute to subsequent heavy drinking and alcohol problems among women, little prospective evidence exists. The present prospective study examined whether sexual victimization contributes to subsequent heavy drinking among a community sample of women, 18-30 years of age (n=927). Using three waves of data, 12 months apart, we examined the impact of T1 sexual victimization on T2 heavy drinking, and of T2 sexual victimization on T3 heavy drinking. There were significant bivariate differences between sexually victimized and non-victimized women on heavy drinking both concurrently and prospectively. However, after controlling for prior heavy drinking and demographic variables, most differences disappeared. We also tested the hypothesis that Post-Traumatic Stress Disorder (PTSD) Symptoms would mediate the relationship between T2 sexual victimization and T3 heavy drinking. Although T2 sexual victimization predicted T2 PTSD symptoms, PTSD did not contribute to subsequent heavy drinking. Findings suggest that heavy drinking is relatively stable over time and that sexual victimization does not make a substantial independent contribution to heavy drinking among women in the general population. 相似文献
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中药重金属限量控制现状与对策 总被引:8,自引:0,他引:8
本文针对国际广泛关注的中药重金属超标现象,综述国内外有关中药重金属的限量标准,结合现代重金属毒理学研究成果和中药自身的特点,分析了中药重金属限量控制现状,提出应从建立科学合理的限量标准与测定方法、严格控制外源性污染和有效去除重金属杂质3个方面解决中药重金属限量问题。 相似文献