Pre-Training Reversible Inactivation of the Basal Amygdala (BA) Disrupts Contextual,but Not Auditory,Fear Conditioning,in Rats

The basolateral amygdala complex (BLA), including the lateral (LA), basal (BA) and accessory basal (AB) nuclei, is involved in acquisition of contextual and auditory fear conditioning. The BA is one of the main targets for hippocampal information, a brain structure critical for contextual learning, which integrates several discrete stimuli into a single configural representation. Congruent with the hodology, selective neurotoxic damage to the BA results in impairments in contextual, but not auditory, fear conditioning, similarly to the behavioral impairments found after hippocampal damage. This study evaluated the effects of muscimol-induced reversible inactivation of the BA during a simultaneous contextual and auditory fear conditioning training on later fear responses to both the context and the tone, tested separately, without muscimol administration. As compared to control rats micro-infused with vehicle, subjects micro-infused with muscimol before training exhibited, during testing without muscimol, significant reduction of freezing responses to the conditioned context, but not to the conditioned tone. Therefore, reversible inactivation of the BA during training impaired contextual, but not auditory fear conditioning, thus confirming and extending similar behavioral observations following selective neurotoxic damage to the BA and, in addition, revealing that this effect is not related to the lack of a functional BA during testing.     

A Food and Drug Administration-approved Asthma Therapeutic Agent Impacts Amyloid β in the Brain in a Transgenic Model of Alzheimer Disease

Interfering with the assembly of Amyloid β (Aβ) peptides from monomer to oligomeric species and fibrils or promoting their clearance from the brain are targets of anti-Aβ-directed therapies in Alzheimer disease. Here we demonstrate that cromolyn sodium (disodium cromoglycate), a Food and Drug Administration-approved drug already in use for the treatment of asthma, efficiently inhibits the aggregation of Aβ monomers into higher-order oligomers and fibrils in vitro without affecting Aβ production. In vivo, the levels of soluble Aβ are decreased by over 50% after only 1 week of daily intraperitoneally administered cromolyn sodium. Additional in vivo microdialysis studies also show that this compound decreases the half-life of soluble Aβ in the brain. These data suggest a clear effect of a peripherally administered, Food and Drug Administration-approved medication on Aβ economy, supporting further investigation of the potential long-term efficacy of cromolyn sodium in Alzheimer disease.     

Antioxidant enzymatic defense in salivary glands of streptozotocin‐induced diabetic rats: a temporal study

Hyperglycemia induces overproduction of superoxide and it is related to diabetic complications. In this study, we analyzed the antioxidant enzymatic defense and the lipid peroxidation of rat salivary glands in six different periods of diabetic condition. Ninety‐six rats were divided into 12 groups: C7/14/21/28/45/60 (non‐diabetic animals) and D7/14/21/28/45/60 (diabetic animals). Diabetes was induced by streptozotocin and the rats were euthanized after 7, 14, 21, 28, 45, or 60 days. Their parotid (PA) and submandibular (SM) glands were removed soon after the sacrifice and the total protein and malondialdehyde (MDA) concentrations, as well as, the superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities were determined. Twenty‐one days after the diabetes induction, the SM glands showed an increase in SOD, CAT, and GPx activities, as well as, MDA concentration. Concerning the PA glands, an increase in the CAT activity and MDA content was observed throughout the observation period. The results suggest that diabetes can cause alterations on the salivary glands and that PA and SM glands react differently when exposed to diabetes condition. However, no impairment of antioxidant system was observed in the group whose diabetic condition had been induced 60 days earlier, herein named 60‐day group. Copyright © 2010 John Wiley & Sons, Ltd.     

亚热带山地亮叶水青冈林的群落分类及物种组成与更新

水青冈属(Fagus)约有11种,我国有5种。亮叶水青冈(Faguslucida)是我国间断分布于亚热带高海拔山地的主要落叶树种。近年来亮叶水青冈林受砍伐严重,为了保护残存的林地,作者采用Braun-Blanquet(1964)、Fujiwara(1987)的植物社会学方法,对分布于中国亚热带山地的南山、梵净山、宽阔水、八大公山4地域的亮叶水青冈林进行了植被的比较研究。根据37个样方调查的资料,区分出3个群丛6个亚群丛。比较3个群丛的物种组成、生活型结构发现,位于南山的毛玉山竹–亮叶水青冈群丛(Yushaniobasihirsuto–Fagetumlucidae)及位于梵净山与宽阔水的大箭竹–亮叶水青冈群丛(Sinarundinariochungii–Fagetumlucidae),其常绿落叶阔叶混交林的特征明显;而八大公山的箭竹–亮叶水青冈群丛(Sinarundinarionitido–Fagetumlucidae),其落叶阔叶林的特征较显著。南山与八大公山的亮叶水青冈林立木结构分析结果表明,前者呈“L”型分布,林窗的存在使亮叶水青冈可以保持更新,密集的竹子是妨碍其自然更新的主要因素;后者呈“Λ”状分布,尽管林下竹子稀疏,自然更新却严重不良,其原因尚待继续定点观测分析。     

Production of l-Tryptophan by Azaserine-resistant Mutants of Brevibacterium flavum

Azaserine-resistant mutants derived from a 5-fluorotryptophan-resistant, l-tryptophan-producing mutant of Brevibacterium flavum, accumulated 10.3 g/liter of l-tryptophan at maximum. The production increased to 11.4 g/liter when l-serine was added. In the mutant, only anthranilate synthase among enzymes of the tryptophan-specific bio synthetic pathway increased in activity to a 2-fold higher level than that in the parent strain, No. 187. Sensitivity of anthranilate synthase to the feedback inhibition was not altered by the mutation. Activity of 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, the first common enzyme for aromatic amino acid biosynthesis, also increased 2.7-fold and was less sensitive to the feedback inhibition by phenylalanine and tyrosine. Tryptophan transport activity in strain A-100 was similar as that in the parent. Azaserine inhibited anthranilate synthase activity by 50% at 0.075 mm. The inhibition was of a mixed type with respect to both the two substrates. Anthranilate synthase of strain A-100 was inhibited in a similar manner to that of the parent.     

Synthesis of Iodoaminoimidazole Arabinoside (IAIA): A Potential Reductive Metabolite of the Spect Imaging Agent,Iodoazomycin Arabinoside (IAZA)

Abstract

The stereospecific synthesis of 1-(5-deoxy-5-iodo-α-D-arabino-furanosyl)-2-aminoimidazole (iodoaminoimidazole arabinoside: IAIA, 2) is described. The reaction of the protected sugar bromide (8) and trifluoroacetamidoimidazole (10B) gave the coupled product (11B), which gave the free nucleoside (4) on deblocking. It was identical with AIA obtained by reduction of AZA (azomycin arabinoside), whose anomeric configuration was found to be a by the X-ray crystallography.