The effect of chewing gum on self-reported nicotine withdrawal: Is it the flavor,the act of chewing,or both?

A healthy alternative that has been shown to lessen the severity of nicotine withdrawal symptoms during brief periods of nicotine abstinence (e.g., 3–4 h) is confectionary chewing gum (Cohen and colleagues, 1997, 1999, & 2001). The current study sought to build upon this line of research by examining the impact of chewing gum on nicotine withdrawal severity over an extended period of nicotine abstinence (e.g., 24 h) while also identifying the specific attributes of chewing gum that may be responsible for the reported decreases in withdrawal. Specifically, the acts of chewing, flavor, as well as the combination of the two, were independently examined. Twenty-four dependent cigarette smokers participated in three experimental conditions (e.g., a flavorless gum base, flavor strips, and flavored chewing gum) as well as a no product control across four weeks while abstaining from smoking for 24 h each week. Using repeated measures ANOVAs, a significant difference in withdrawal severity was reported by participants across conditions, F(3, 69) = 2.89, p < .05. Follow-up analyses revealed that the flavored gum condition yielded significantly lower withdrawal scores than the flavorless gum base and no product control conditions. These findings indicate that chewing gum appears useful in lessening the severity of nicotine withdrawal symptoms over a 24-hour period of nicotine abstinence and that it is a combination of flavor and chewing that appears to lead to this effect.     

溶氧对黄原胶发酵的影响

黄原胶是野油菜黄单孢菌分泌的胞外多糖,可用淀粉或葡萄糖为碳源发酵生产。本文着重以淀粉为碳源研究不同的溶氧水平对多糖的影响。试验结果表明:溶氧水平高于饱和度的20%对多糖发酵影响不大,低于20%时菌的生长受影响。溶氧水平为饱和度的25%,菌体生长最佳。     

Development of vaginal rings for sustained release of nonhormonal contraceptives and anti-HIV agents

OBJECTIVES: Construction of vaginal rings to deliver nonhormonal contraceptives and 3'-azido-3'-deoxythymidine (AZT) as an anti-HIV agent and determination of their daily release and efficacy in vitro. MATERIALS AND METHODS: Intravaginal rings of 0.5-0.7 cm rim and 5-5.5 cm in diameter were cast in the molds. The rings were composed of biosoluble acacia gum or nonbiodegradable hydrogel of 2-hydroxyethyl methacrylate (HEMA) and sodium methacrylate (SMA) [P(HEMA-co-SMA)]. The rings were impregnated with nonhormonal contraceptives such as ferrous gluconate to cause spermiostasis, l-ascorbic acid to increase the viscosity of the cervical mucus, and pharmalytes of pH 4-5 or AZT. RESULTS: The daily release rate of nonhormonal contraceptives as well as AZT from the rings was efficacious in vitro. Cumulative effect of nonhormonal contraceptives showed complete spermiostasis within 30 s up to 10 and 28 days, respectively. Daily release of AZT from both rings was also likely to be efficacious to inhibit HIV proliferation in vitro for 10 and 28 days, respectively. CONCLUSION: The data indicate that the rings described here can be developed for intravaginal delivery of nonhormonal contraceptives and/or anti-HIV agents.     

Evidence against memorial facilitation and context-dependent memory effects through the chewing of gum

The experiment examined the prediction that chewing gum at learning and/or recall facilitated subsequent word recall. Chewing gum at learning significantly impaired recall, indicating that the chewing of gum has a detrimental impact upon initial word encoding. In addition, a context-dependent memory effect was reported for those participants who both learned and recalled in the absence of gum; however, a context-dependent effect was not found with chewing gum. The findings contradict previous research.     

桃胶改良前后的溶胀性能分析

目的:阐明溶剂、盐浓度、温度及p H对桃胶改良前后溶胀性能的影响,为阐明其缓释性能提供实验依据。方法:采用称重法测定原桃胶和改良桃胶辅料溶胀前后的干重、湿重,计算平衡溶胀率。结果:在不同溶剂中,改良桃胶的平衡溶胀率普遍明显高于原桃胶;桃胶改良前后的平衡溶胀率为二甲基亚砜水无水乙醇;在不同盐浓度中,桃胶改良前后的平衡溶胀率基本相同,均不受盐浓度影响,但显著小于水;在不同温度中,温度越高,桃胶改良前后的溶胀性能均越大,且改良桃胶更优;在不同p H溶液中,原桃胶易受酸碱度影响,而改良桃胶的平衡溶胀率不受其影响,且表现出更佳的溶胀性能。结论:改良桃胶的溶胀性能显著优于原桃胶;桃胶改良前后的溶胀性能受溶剂、温度的影响显著,而对盐浓度和p H(原桃胶易受影响)则不敏感。     

Proabsorptive Action of Gum Arabic in Isotonic Solutions Orally Administered to Rats. II. Effects on Solutes Under Normal and Secretory Conditions

Gum arabic (GA) is a natural proteoglycan with proabsorptive capacity attributable to its physico-chemical properties. Previous experiments showed that in rats oral administration of GA in an isotonic solution had a generally positive effect. This study extends the investigation to include acetaminophen and to evaluate whether GA could also act under secretory conditions induced by theophylline. Test solutions were orally administered to rats under CO2 anesthesia and blood concentrations followed for 3 hr. The secretory effects of theophylline were clearly observed for sodium and zinc. Addition of GA resulted in a more rapid rate of glutamate absorption, under normal physiologic conditions, as indicated by the higher area under the curve (AUC). There were no differences in the presence of theophylline. Acetaminophen blood concentrations peaked about 30 min after administration, and the AUC in rats that received GA was higher than in those that got the solution without GA. AUCs for total body water distribution with time and those for glucose concentrations were indistinguishable whether the solutions contained or did not contain either GA or theophylline. The results confirm that oral administration of GA can accelerate absorption of some solutes, including pharmacologic agents.     

重组人粒细胞-巨噬细胞集落刺激因子对兔牙龈创伤愈合的促进作用

目的：探讨重组人粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)对于牙龈创伤修复的影响,为其在口腔牙周领域中的应用奠定基础。方法：16只健康大耳白兔随机分为实验组和对照组,每组8只。采用手术刀切除上下切牙唇侧牙龈2 mm。术后实验组每日3次创面涂抹rhGM-CSF,对照组以生理盐水替代。于术后3、7、11和15 d各处死动物2只,HE染色观察镜下上皮及上皮下结缔组织的结构、分布,各种创伤修复细胞的变化,PCNA染色后观察阳性染色上皮细胞和成纤维细胞数目。结果：形态学观察,第3天2组均表现出炎细胞浸润,但实验组浸润数目更多;第7天2组均可见到新生血管、成纤维细胞和胶原纤维,实验组新生血管化的程度较为显著;第11天2组出现大量增殖的成纤维细胞,但实验组和程度更广泛,至第15天时2组的创伤均已基本恢复正常,组间差异不明显。PCNA染色,随着时间的推移,增殖的上皮细胞数目逐渐增加,至第15天时达到高峰,增殖的成纤维细胞数目从第3天起开始增加,至第11天达到高峰,第15天则明显降低为最低值。实验组增殖的上皮细胞数量在第3和11天显著高于对照组（P<0.01）,增殖的成纤维细胞数量在第11和15天明显高于对照组（P<0.05）,其余时间点组间比较差异均无统计学意义（P>0.05）。结论：rhGM-CSF可以促进牙龈组织中炎细胞的浸润、血管的新生、上皮细胞和成纤维细胞的增殖,rhGM-CSF可以促进牙龈组织创伤愈合。     

An experimental study of Newtonian and non-Newtonian flow dynamics in an axial blood pump model

The head curves of a 1.5:1 new axial blood pump model were measured using five working fluids at five rotational speeds. The working fluids were water, a 39wt% aqueous glycerin solution (GS), and three aqueous xanthan gum solutions (XGSs) with different concentrations. The flow velocities and shear stresses in the mechanical clearance between the casing and rotor were investigated using a laser Doppler velocimeter and hot-film sensor. At every rotational speed, the experiment in which viscous GS was used in the pump model showed a head curve lower than that obtained using water, whereas the head obtained using viscoelastic XGS was higher than that generated using water. A maximum difference of 65.8% between the heads measured in the 0.06% XGS and GS experiments was detected. The higher head produced by the XGS may have originated from the drag-reduction effect of XGS viscoelasticity. The measurements showed that a reverse washout flow at a velocity of 0.05-0.11m/s occurs in the clearance. This reverse washout flow is crucial to preventing flow stagnation and accompanying thrombus formation. The wall shear stress and the Taylor number of the rotating Couette-like flow in the clearance both indicated that it is a turbulent flow.     

The safety of gum arabic as a food additive and its Energy Value as an ingredient: a brief review

Gum arabic, the natural exudate from Acacia senegal (L.) Willd., has enjoyed the toxicological status 'ADI not specified' for use in minor proportions as a food additive (E414 in the EEC) since 1982, but it is also used as a major ingredient. Manufacturers may therefore be required to make labelling declarations of its Energy Value and of available/non-available carbohydrate. Although gum arabic complies with the definition for soluble dietary fibre, its Energy Value was accepted by the FAO/WHO International Programme of Food Safety to be 4 kcal/gram on the basis of the evidence available in 1982. Subsequently a French claim for a much lower value attracted the attention of manufacturers of low calorie products but a recent precise experiment establishes that the Digestible Energy Value is 3.5 ± 0.12 kilocalories per gram. The physiological mechanism whereby this value arieses is outlined. The more general dietary implications for other complex carbohydrates which conform to the definition for soluble dietary fibre and yet suffer complete degradation in the large bowel are indicated.