Endogenous brain angiotensin II disrupts passive avoidance behavior in rats

The presence of angiotensinogen, the precursor of angiotensin II (ANG II), in brain tissue and in cerebrospinal fluid (CSF) allows stimulation of endogenous brain ANG II by renin. Passive avoidance tests were performed in female Wistar rats. The animals received an electrical shock after entering a black box on the first experimental day. Avoidance was tested every 24 h for 5 consecutive days. Renin in doses of 0.01 and 0.1 units was injected once into the lateral brain ventricles 2 min before the first test. CSF ANG II increased from 40 to 4547 and 5152 fmol per ml (means), respectively. A dose-dependent disruption of avoidance learning was observed, the frequency to enter the black box increasing from 11% (control) to 29% and 46%, and the latency decreasing from 165 (control) to 143 and 116 sec, respectively. These effects were statistically significant (P less than 0.001) for more than 24 h and returned to control levels after 48 to 120 h. Administration of the converting-enzyme inhibitor SQ 14225 i.v.t. prior to renin injections abolished the renin effects. Injections of renin given 22 h after learning were without effect.     

Dexamethasone loaded bioresorbable films used in medical support devices: structure, degradation, crystallinity and drug release

Bioresorbable polymer films containing dexamethasone (DM) were prepared using a solution processing technique. Investigation of the films focused on cumulative DM release as affected by film morphology (drug location/dispersion in the film) and degradation processes. Two film structures were studied: A-type, a polymer film with large drug crystals located on the film’s surface, and B-type, a polymer film with small drug particles and crystals distributed within the bulk. The effect of the polymer’s degree of crystallinity on the drug release profile was also studied. Prototypical applications of these films are biodegradable medical support devices which combine mechanical support with drug release. In most of our studied systems the drug release profile from the film is determined mainly by both drug location/dispersion in the film and the polymer’s weight loss rate. All release profiles from A-type films exhibited a burst effect of approximately 30%, accompanied by a second release phase at a constant rate, whereas the release profiles from B-type films were determined mainly by the degradation profile of the host polymer, and did not exhibit any burst effect. A high degree of crystallinity is important for the current application, since good mechanical properties are required. This contributes to slower drug release rates, mainly at relatively low weight losses, whereas at high weight losses, where a porous structure is created, the crystallinity almost does not affect the rate of drug release. The shape of the porous structure that develops with degradation also affects the drug release profile from the B-type films.     

Binding of influenza viruses to sialic acids: reassortant viruses with A/NWS/33 hemagglutinin bind to alpha2,8-linked sialic acid

We have examined the specificity of binding of A/NWS/33 hemagglutinin (HA), exploring the effects of fucosylation, changing the Gal-GlcNAc linkage between the second and third sugars, and binding affinity for alpha2,8-linked sialic acid. The HA of A/NWS/33(HA)-Tokyo/67(NA) (NWS-Tok, H1N2) virus binds to 3'-linked sialyllactose with 10-fold higher affinity than 3' sialyllactosamine and 3-fold higher affinity than 6' sialyllactosamine. The P227H mutation in A/NWS/33(P227H)(HA)-A/Memphis/31/98(NA) (NWS-Mem/98, H1N2) results in sevenfold lower affinity for 3' sialyllactose, but binding to 6' sialyllactosamine is unchanged. The apparent switch from 3' to 6' specificity is solely due to a loss of Siaalpha2,3 binding. Fucosylation of the third sugar and changing the linkage between second and third sugars had little effect on binding by NWS-Tok, but marked effects on A/NWS/33(P227H)(HA)-tern/Australia/G70c/75(NA) (NWS-G70c, H1N9) and NWS-Mem/98. NWS-Tok, NWS-G70c, and NWS-Mem/98 bind to alpha2,8-bisialic acid with high affinity. NWS-Mem/98 can also bind to alpha2,8-trisialic acid, but with lower affinity. Together, these data show that alpha2,8-linked sialic acid, fucosylation of the third sugar, and linkage between the second and third sugars could play important roles in allowing efficient virus binding to its host cell. The finding that influenza viruses have the potential to bind to alpha2,8-linked sialic acid is a new influenza virus-receptor interaction pathway.     

Molecular epidemiological and clinical aspects of hepatitis D virus in a unique triple hepatitis viruses (B,C, D) endemic community in Taiwan

The molecular epidemiological and clinical aspects of hepatitis D virus (HDV) in a unique HBV, HCV, and HDV triple virus endemic community in southern Taiwan were investigated. A total of 2,909 residents aged 45 or older were screened for hepatitis B surface antigen (HBsAg), anti-HCV antibody, and anti-HDV antibody (specifically for HBsAg-positive carriers). Factors that might be associated with HDV infection, viral nucleic acid detection, and genotyping of HBV, HCV, and HDV were investigated. The prevalence of HBsAg and anti-HCV were 12.6% (366/2,909) and 41.6% (1,227/2,909), respectively. For HBsAg carriers, 15.3% (56/366) were positive for anti-HDV assay. Living in a higher endemic district of HCV infection (odds ratio [OR] = 3.2; 95% confidence interval [CI] = 1.7-6.3), male gender (OR = 1.9; 95% CI = 1.1-3.6) and co-infection with HCV (OR = 1.8; 95% CI = 1.0-3.3) were significantly independent factors associated with HDV infection. The detection rate of HDV RNA among anti-HDV-positive patients was only 12.7% (7/55). The mean HBV titer of triple infection group was significantly lower than in the HBV/HDV co-infection group (2.23 vs 3.05 in log(10), copies/ml, P = 0.046). HCV RNA detection among the triple infection group showed 47.4% (9/19) viremia rate and viral loads of 579,121 IU/ml in median (16,803-1,551,190 IU/ml). The prevalent genotype of HBV was type B (23/25); HCV was 1b (7/9) and HDV was IIa/IIb (4/4). Only the presence of HCV RNA predicted the presence of elevated ALT significantly (OR = 25.0; 95% CI = 3.39-184.6). In conclusion, the geographical aggregation of HDV infection paralleled that of HCV infection in this community. HCV suppressed the replication of HBV among triple vital infection patients. HBV and HDV lapsed into a remission or nonreplicative phase in most cases, and HCV acted as a dominant factor in triple viral-infected individuals. Only the presence of HCV RNA was associated with elevated ALT values, but not HBV or HDV.     

谷氨酸诱导海马神经元凋亡涉及线粒体释放细胞色素C

目的：建立体外谷氨酸诱导神经元兴奋损伤模型，探索其凋亡发生是否通过线粒体信号转导途径介导的细胞色素C（Cyt C）释放而实现，为今后干预性使用神经保护剂提供依据。方法:分离及培养新生Wistar大鼠海马神经元，选用合适谷氨酸浓度建立神经元损伤模型；利用LDH测定及流式细胞仪Annexin V/PI双染色法检测谷氨酸暴露后不同时点神经元凋亡及坏死的动态改变；采用Western blotting法检测caspase-3活性及线粒体内和胞浆内Cyt C水平动态变化。结果:谷氨酸诱导神经元损伤呈明显浓度及时间依赖性，50 μmol/L浓度可使LDH释放量明显增加 (18.4%,P<0.05)，暴露后6 h凋亡率显著增加；凋亡发生前，神经元caspase-3活性已明显增高（3 h），6 h达高峰；线粒体Cyt C释放发生在caspase-3增高前，30 min时胞浆内Cyt C水平即明显增加（P<0.05），3 h胞浆内Cyt C水平超过线粒体内，而线粒体内Cyt C水平进行性减少。结论:50 μmol/L谷氨酸可诱导海马神经元凋亡，凋亡机制可能是通过损伤线粒体膜，使Cyt C易位释放入胞浆激活caspase级联反应而致。     

Developmental regulation of type 1 and type 3 interferon production and risk for infant infections and asthma development

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Mismatched hemagglutinin and neuraminidase specificities in recent human H3N2 influenza viruses

The hemagglutinin (HA) of influenza viruses initiates infection by binding to sialic acid on the cell surface via alpha2,6 (human) or alpha2,3 (avian) linkage. The influenza neuraminidase (NA) can cleave both alpha2,3- and alpha2,6-linked sialic acids, but all influenza NAs have a marked preference for the non-human alpha2,3 linkage. Recent H3N2 influenza viruses have lost the ability to agglutinate chicken red blood cells. To determine if changes in HA specificity or affinity correlate with NA specificity or activity, we examined red cell binding and elution of a series of H3N2 viruses. We found that the NA activity of many influenza viruses does not release binding by their HA. In some egg-adapted strains, lack of elution correlates with low levels of viral NA activity, and these elute rapidly when bacterial NA is added. However, a Fujian-like virus, A/Oklahoma/323/03, does not elute by its own NA or with Vibrio cholerae sialidase, and it binds to red cells pre-treated with V. cholerae sialidase. It elutes after addition of the broad specificity Micromonospora viridifaciens sialidase. Human glycophorin inhibits A/Oklahoma/323/03 hemagglutination 6-fold better than fetuin. We conclude that specific forms of sialic acid are used as receptor by recent human H3N2 influenza viruses, perhaps involving branched alpha2,6 sialic acid or alpha2,8 sialic acid structures on O-linked carbohydrates. The virus itself has no O-linked glycans, so even though the NA is not able to cleave receptors on cells, the viruses will not self-aggregate. It will be important to monitor efficacy of neuraminidase inhibitors in case there are NA-resistant receptors in the human respiratory tract that allow the viruses to be less dependent on NA activity.     

上海人群面肩肱型肌营养不良症相关位点的D4Z4多态性

目的 对上海人群4p35位点D4Z4重复序列进行研究，分析D4Z4的多态性。方法 191名正常上海人的基因组DNA经EooR I/Bln I双酶水解后，应用脉冲场凝胶电泳及Southem印迹测定其染色体4p35位点的D4Z4片段长度，并对短的D4Z4片段Kpn I酶进行部分酶切以计数其D4Z4串联重复序列数。结果 在191名正常上海人群中，有17人（占8.9％）携带短的D4Z4片段，其长度在22－34kb之间；其中16人携带的短D4Z4片段位于4q35位点，1人携带的短D4Z4片段为4q35→10q26。结论 面肩肱型肌营养不良症的发病虽与4q35位点D4Z4片段的串联重复序列数减少有关，但上海人群中携带4q35位点短的D4Z4片段个体的比例明显高于西方人群，提示其他因素可能也参与面肩肱型肌营养不良症的发病。     

Effects of cyclopiazonic acid on Ca2+ regulation by the sarcoplasmic reticulum in saponin-permeabilized skeletal muscle fibres

 The effects of the sarcoplasmic reticulum (SR) Ca²⁺ pump inhibitor cyclopiazonic acid (CPA) were studied in saponin-permeabilized frog skeletal muscle fibres. Release of Ca²⁺ from the SR was triggered by brief (2 s) applications of 40 mM caffeine at 2-min intervals. Changes in [Ca²⁺] within the fibre were monitored continuously using Fura-2 fluorescence. At a bathing [Ca²⁺] of 100 nM, introduction of 20 μM CPA induced a slow release of Ca²⁺ from the SR. The following one to two caffeine-induced Ca²⁺ transients were markedly increased in amplitude and duration. Thereafter, the caffeine-induced Ca²⁺ transients decreased progressively and were barely detectable 6–7 min after introduction of CPA. However, increasing the bathing [Ca²⁺] or increasing the Ca²⁺ loading period resulted in a partial recovery of the caffeine-induced Ca²⁺ transients, suggesting that pump inhibition is incomplete, even in the presence of 100 μM CPA. The slow Ca²⁺ efflux induced by CPA was insensitive to ryanodine, but absent following abolition of SR Ca²⁺ pump activity by ATP withdrawal. These results suggest that the caffeine-induced Ca²⁺ transient reflects a balance between efflux via the SR Ca²⁺ channel and reuptake by the Ca pump. Ca²⁺ release upon addition of CPA may result from inhibition of SR Ca²⁺ uptake, which reveals a tonic Ca²⁺ efflux that is independent of the Ca²⁺ release channels. Received: 26 November 1997 / Received after revision: 12 January 1998 / Accepted: 13 January 1998