Effect of Alkyl Groups of Latent Cationic Catalysts on Cure and Dynamic Mechanical Behaviors of Epoxy Resins

Summary: The latent thermal cationic initiators, benzyl‐2,5‐dimethylpyrazinium hexafluoroantimonate (BDPH) and benzyl‐2‐ethylpyrazinium hexafluoroantimonate (BEPH), were synthesized to investigate the effect of substituted alkyl groups on cure and dynamic mechanical behaviors of difunctional epoxy system. The cure temperature and activation energy of the diglycidyl ether of bisphenol A (DGEBA)/BDPH were higher than those of the DGEBA/BEPH, resulting from the steric hindrance of the substituted groups. The cross‐linking density of the DGEBA/BDPH was higher than that of the DGEBA/BEPH, whereas the T_g's of both specimens are similar. This may be explained by the free volume and the intermolecular hydrogen bonding induced by the hydrogen of the substituted methyl groups. Consequently, the position and number of the substituted groups of the latent thermal initiator were very important in the control of the latent thermal and dynamic mechanical behaviors of the epoxy resin.

Dynamic DSC curves of DGEBA cured by each initiator.     

Leukotriene B4 Receptor (BLT-1) Modulates Neutrophil Influx into the Peritoneum but Not the Lung and Liver during Surgically Induced Bacterial Peritonitis in Mice

Leukotriene B₄ (LTB₄) is a rapidly synthesized, early neutrophil chemoattractant that signals via its cell surface receptor, BLT-1, to attract and activate neutrophils during peritonitis. BLT-1-deficient (BLT-1^−/−) mice were used to determine the effects of LTB₄ on neutrophil migration and activation, bacterial levels, and survival after cecal ligation and puncture (CLP). Male BLT-1^−/− or wild-type (WT) BALB/c mice underwent CLP. Tissues were harvested for determination of levels of bacteria, myeloperoxidase (MPO), LTB₄, macrophage inflammatory protein 2 (MIP-2), and neutrophil (polymorphonuclear leukocyte [PMN]) numbers at 4 and 18 h after CLP. PMN activation was determined by an assessment of phagocytosis ability and CD11b expression. Survival was also determined. BLT-1^−/− mice had decreased numbers of PMNs in the peritoneum at both 4 and 18 h after CLP but increased numbers of PMNs in the blood at 18 h compared with WT mice. Liver and lung MPO levels were significantly higher in BLT-1^−/− mice at both 4 and 18 h after CLP, with increased bacterial levels in the blood, the liver, and peritoneal fluid at 4 h. Bacterial levels remained higher in peritoneal fluid at 18 h, but blood and liver bacterial levels at 18 h were not different from levels at 4 h. PMN phagocytosis and CD11b levels were decreased in BLT-1^−/− mice. LTB₄ levels were similar between the groups before and after CLP, but MIP-2 levels were decreased both locally and systemically in BLT-1^−/− mice. Survival was significantly improved in BLT-1^−/− mice (71%) compared with WT mice (14%) at 48 h post-CLP. Thus, LTB₄ modulates neutrophil migration into the mouse peritoneum, but not the lung or liver, after CLP. Despite higher bacterial and PMN levels at remote sites, there was increased survival in BLT-1^−/− mice compared to WT mice. Decreased PMN activation may result in less remote organ dysfunction and improved survival.     

汉族人群载脂蛋白CII基因二核苷酸串联重复序列(TG)n(AG)m及(AG)m多态性

采用套式聚合酶链反应结合变性聚丙烯酰胺凝胶电泳和银染技术，并构建载脂蛋白CII（ApoCII)基因二核苷酸串联重复序列（TG）n(AG)m及（AG）m序列等位基因梯阶标准；检测正常汉族人群基因型和等位基因频率分布，检出36种（TG）n(AG)m序列基因型、12种等位基因。等位基因为17、18、26－35，其频率分别为0．061、0．011、0．002、0．002、0．054、0．255、0．372、0．084、0．026、0．039、0．052、0．041。检出7种（AG）m序列基因型、4种等位基因。等位基因为6、7、8、9，其频率分别为0．002、0．152、0．812、0．034。与欧洲白种人比较，ApoCII基因二核苷酸串联重复序列（TG）n(AG)m及（AG）m序列等位基因频率分布均具有明显的种族差异性（P＜0．01，P＜0．01）。     

山莨菪碱对中性粒细胞糖皮质激素受体的影响

以~3H地塞米松(Dex)为特异性配基,以一点分析法测得大白鼠腹腔中性粒细胞(PMNs)的糖皮质激素受体(GCR)位点数为5270±216/个PMN(n=18,X±SE下同);体外实验,PMNs直接与山莨菪碱(654-23×10~(-5)M)温育,对GCR无明显影响,测得位点数为4896±360/个PMNs(n=20,P>0.4);体内实验表明,给大鼠肌肉注射654-2(10mg/kg)每日两次共二天,则GCR位点数降至2740±101/个PMNs(n=18,P<0.001)。此时还测得血浆皮质酮含量明显增高(P<0.01)。提示654-2对GCR的影响可能与增加皮质激素所致的“降调节”有关。     

Assault injury rates,social capital,and fear of neighborhood crime

This study develops an explanatory framework for fear of neighborhood crime based on respondents' social context and local rates of assault injuries. Rates of assault injuries within zip codes are based on hospital discharge records. We find that only four variables have a significant unique contribution to fear of crime: respondent's sex, perceptions of neighborhood social capital, and the rates of struck by/against assault injuries for the 10–24 and 50+ age groups. We also find that the perception of neighborhood social capital moderates the impact of assault injury rates on fear of crime; those who perceive a high level of neighborhood social capital exhibit less sensitivity to assault injury rates. We include a map of assault injury rates and fear of crime by ZIP Code and describe the community context related to our results. © 2007 Wiley Periodicals, Inc. J Comm Psychol 35: 483–498, 2007.     

Mechanisms underlying regulation of respiratory pattern by nicotine in preBötzinger complex

Cholinergic neurotransmission plays a role in regulation of respiratory pattern. Nicotine from cigarette smoke affects respiration and is a risk factor for sudden infant death syndrome (SIDS) and sleep-disordered breathing. The cellular and synaptic mechanisms underlying this regulation are not understood. Using a medullary slice preparation from neonatal rat that contains the preB?tzinger Complex (preB?tC), the hypothesized site for respiratory rhythm generation, and generates respiratory-related rhythm in vitro, we examined the effects of nicotine on excitatory neurotransmission affecting inspiratory neurons in preB?tC and on the respiratory-related motor activity from hypoglossal nerve (XIIn). Microinjection of nicotine into preB?tC increased respiratory frequency and decreased the amplitude of inspiratory bursts, whereas when injected into XII nucleus induced a tonic activity and an increase in amplitude but not in frequency of inspiratory bursts from XIIn. Bath application of nicotine (0.2--0.5 microM, approximately the arterial blood nicotine concentration immediately after smoking a cigarette) increased respiratory frequency up to 280% of control in a concentration-dependent manner. Nicotine decreased the amplitude to 82% and increased the duration to 124% of XIIn inspiratory bursts. In voltage-clamped preB?tC inspiratory neurons (including neurons with pacemaker properties), nicotine induced a tonic inward current of -19.4 +/- 13.4 pA associated with an increase in baseline noise. Spontaneous excitatory postsynaptic currents (sEPSCs) present during the expiratory period increased in frequency to 176% and in amplitude to 117% of control values; the phasic inspiratory drive inward currents decreased in amplitude to 66% and in duration to 89% of control values. The effects of nicotine were blocked by mecamylamine (Meca). The inspiratory drive current and sEPSCs were completely eliminated by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) in the presence or absence of nicotine. In the presence of tetrodotoxin (TTX), low concentrations of nicotine did not induce any tonic current or any increase in baseline noise, nor affect the input resistance in inspiratory neurons. In this study, we demonstrated that nicotine increased respiratory frequency and regulated respiratory pattern by modulating the excitatory neurotransmission in preB?tC. Activation of nicotinic acetylcholine receptors (nAChRs) enhanced the tonic excitatory synaptic input to inspiratory neurons including pacemaker neurons and at the same time, inhibited the phasic excitatory coupling between these neurons. These mechanisms may account for the cholinergic regulation of respiratory frequency and pattern.     

小儿肝的年龄解剖学研究

分六个年龄组观察了180个(男98,女82)小儿肝的形态、度量、位置及体表投影.小儿肝相对较大,右叶大于左叶,下界位置较低并逐渐上移.在右锁骨中线的肋弓下一般均可触到.小儿肝重随其年龄(身高)的增长而增长,其增长速度相对较慢,尤以Ⅶ组小儿更明显.     

A polymorphic major histocompatibility complex class II‐like locus maps outside of both the chicken B‐system and Rfp‐Y‐system

Chickens have two major regions encoding major histocompatibility complex (MHC) class Iα genes and MHC class IIß genes, the serological and functional B‐system and the Rfp‐Y‐system. Recently, they have been shown to assort in a genetically independent way although still located on the same microchromosome. Moreover, the monomorphic MHC class IIα gene maps at a third locus located 5 c m from the nearest class IIß genes, located in the B‐system ( Kaufman et al., 1995 ). A pedigree family was studied in three generations in order to assign MHC class IIß restriction fragments observed in Southern blot analyses to either the B‐system, the Rfp‐Y‐system or the B‐Lα locus. In this study, we demonstrate by classical genetic testing of chickens within this fully pedigreed family the existence of an MHC class II‐like polymorphic restriction fragment that segregates independently of the B‐system, the Rfp‐Y‐system and of the B‐Lα locus.     

Cloning, expression and characterization of a murine-human chimeric antibody with specificity for pre-S2 surface antigen of hepatitis B virus

The cloning, expression and characterization of a murine-human chimeric antibody with specificity for the pre-S2 surface antigen (Ag) of hepatitis B virus (HBV) is described. The heavy and light chain variable region (VH and VL) genes encoding the murine monoclonal antibody (mAb) were isolated and combined with human γ 1 and κ constant region genes, respectively. The expression vectors containing the chimeric heavy and light chain genes were sequentially electroporated into murine Sp2/0 hybridoma cells and transfectomas secreting chimeric antibody were isolated. The chimeric antibody was purified and characterized by ELISA, Western analysis and competition immunoassay, demonstrating that the transfectoma functionally express and secrete murine-human chimeric antibody which retained the specificity and affinity of the parental murine mAb.