The Highwire Ubiquitin Ligase Promotes Axonal Degeneration by Tuning Levels of Nmnat Protein

Axonal degeneration is a hallmark of many neuropathies, neurodegenerative diseases, and injuries. Here, using a Drosophila injury model, we have identified a highly conserved E3 ubiquitin ligase, Highwire (Hiw), as an important regulator of axonal and synaptic degeneration. Mutations in hiw strongly inhibit Wallerian degeneration in multiple neuron types and developmental stages. This new phenotype is mediated by a new downstream target of Hiw: the NAD+ biosynthetic enzyme nicotinamide mononucleotide adenyltransferase (Nmnat), which acts in parallel to a previously known target of Hiw, the Wallenda dileucine zipper kinase (Wnd/DLK) MAPKKK. Hiw promotes a rapid disappearance of Nmnat protein in the distal stump after injury. An increased level of Nmnat protein in hiw mutants is both required and sufficient to inhibit degeneration. Ectopically expressed mouse Nmnat2 is also subject to regulation by Hiw in distal axons and synapses. These findings implicate an important role for endogenous Nmnat and its regulation, via a conserved mechanism, in the initiation of axonal degeneration. Through independent regulation of Wnd/DLK, whose function is required for proximal axons to regenerate, Hiw plays a central role in coordinating both regenerative and degenerative responses to axonal injury.     

穿越海南

2001年4月6日 晴 从飞机的舷梯上走下来,一股温湿的风立刻笼罩了我,海南——在我对它有过多次幻想之后的今天,终于又再次踏上了这块葱绿的土地。在接到拍摄任务的几天之内,我甚至请朋友用纸牌占卜——此行安否?答案是有惊无险!唯物主义的我穿着套头衫在北京料峭的春风中登上了飞机,开始了我的穿越海南之行。     

两种南亚热带林下灌木叶片水分特性的比较研究

鼎湖山南亚热带针叶—阔叶混交林下灌木桃金娘和三叉苦叶片气孔导度的日进程多为单峰形。一天中出现气孔导度高值的时间随季节而异,从3月到10月逐渐提前。夏季气孔导度最大,冬季最小。8月份生长于坡顶群落中的两种灌木叶片气孔出现“午睡”现象。不同生长地点中,桃金娘的气孔导度均明显高于三叉苦。叶片水势从早晨起逐渐降低,中午达最低值,随后有所回升。 3月和8月的水势较高,12月水势最低。水势与气孔导度间呈双曲线关系。压力—体积曲线的测定表明叶片水势低值时仍能维持正膨压。     

携带siSPK1重组腺病毒的构建及其对N2a细胞凋亡的影响

应用AdMax腺病毒载体系统构建携带siSPK1基因的重组腺病毒,进一步研究SPK1基因对N2a细胞凋亡的影响。设计可形成小发夹结构的SPK1-siRNA模板cDNA序列,克隆至质粒pDC316-siRNA,构建SPK1-siRNA穿梭质粒pDC316-SPK1,经鉴定正确后,将pDC316-SPK1与辅助包装质粒（pBHG loxΔE1,3 Cre）共转染至HEK293细胞,包装纯化并扩增重组腺病毒颗粒,终点稀释法测定病毒滴度;病毒感染N2a细胞,Western blot法检测SPK1蛋白的表达;Hoechst33258染色检测SPK1基因对N2a细胞凋亡的影响。酶切后PCR分析、测序鉴定表明,pDC316-SPK1构建成功,病毒纯化后滴度为2.50E＋10 PFU/mL;重组病毒可在蛋白水平抑制SPK1的表达;SPK1基因抑制后,N2a细胞凋亡增加（P〈0.001）。上述结果表明,含有SPK1-siRNA的重组腺病毒构建成功,且具有抑制SPK1蛋白表达的功能,该基因沉默后,N2a细胞凋亡增加。     

综合性医院重症监护病房病原菌分离情况分析

目的探讨重症监护病房（Icu）医院内感染的临床特点及病原菌种类、分布情况,为临床合理使用抗菌药物、预防和控制医院感染提供参考和依据。方法采用前瞻性监测与回顾性调查相结合的方法,对ICU患者的临床资料进行统计分析。结果ICU病人标本中分离出病原菌593株,得出菌种分布与感染情况。结论重症监护病房医院内感染发生率高,以呼吸道感染为主,主要病原菌以革兰阴性非发酵菌为主,加强ICU患者感染的控制,可减少ICU医院内感染的发生。     

Sulforaphane inhibits pancreatic cancer through disrupting Hsp90–p50Cdc37 complex and direct interactions with amino acids residues of Hsp90

Sulforaphane [1-isothiocyanato-4-(methyl-sulfinyl) butane)], an isothiocyanate derived from cruciferous vegetables, has been shown to possess potent chemopreventive activity. We analyzed the effect of sulforaphane on the proliferation of pancreatic cancer cells. Sulforaphane inhibited pancreatic cancer cell growth in vitro with IC₅₀s of around 10–15 μM and induced apoptosis. In pancreatic cancer xenograft mouse model, administration of sulforaphane showed remarkable inhibition of tumor growth without apparent toxicity noticed. We found that sulforaphane induced the degradation of heat shock protein 90 (Hsp90) client proteins and blocked the interaction of Hsp90 with its cochaperone p50^Cdc37 in pancreatic cancer cells. Using nuclear magnetic resonance spectroscopy (NMR) with an isoleucine-specific labeling strategy, we overcame the protein size limit of conventional NMR and studied the interaction of sulforaphane with full-length Hsp90 dimer (170 kDa) in solution. NMR revealed multiple chemical shifts in sheet 2 and the adjacent loop in Hsp90 N-terminal domain after incubation of Hsp90 with sulforaphane. Liquid chromatography coupled to mass spectrometry further mapped a short peptide in this region that was tagged with sulforaphane. These data suggest a new mechanism of sulforaphane that disrupts protein–protein interaction in Hsp90 complex for its chemopreventive activity.     

Novel N-oxide derivatives of benzyltetrahydroisoquinoline alkaloid from the tubers of Stephania viridiflavens H.S. Lo et M. Yang

An investigation on the phytochemistry of the medicinal plant Stephania viridiflavens H.S. Lo et M. Yang led to isolate two new naturally occurring benzyltetrahydroisoquinoline alkaloids, (+)-1S, 2R-laudanidine-N_β-oxide 2 and (+)-1S, 2S-laudanidine-N_α-oxide 3, along with four known benzyltetrahydroisoquinoline alkaloids: (+)-laudanidine 1, (+)-reticuline 4, (+)-1S, 2R-reticuline-N_β-oxide 5 and (+)-1S, 2S-reticuline-N_α-oxide 6. The structure and the stereochemistry of these compounds were determined on the basis of spectroscopic methods and also confirmed by partial synthesis. To examine putative acetycholinesterase (AChE) inhibitory or cytotoxic activities, various bioassays were performed, the N-oxide derivatives (5 and 6) demonstrated more potent cytotoxicity than the corresponding free base.     

Functional and Anatomical Connectivity Abnormalities in Cognitive Division of Anterior Cingulate Cortex in Schizophrenia

Introduction

Current pathophysiological theories of schizophrenia highlight the role of altered brain functional and anatomical connectivity. The cognitive division of anterior cingulate cortex (ACC-cd) is a commonly reported abnormal brain region in schizophrenia for its importance in cognitive control process. The aim of this study was to investigate the functional and anatomical connectivity of ACC-cd and its cognitive and clinical manifestation significance in schizophrenia by using the resting-state functional magnetic resonance imaging (fMRI) and the diffusion tensor imaging (DTI).

Methods

Thirty-three medicated schizophrenics and 30 well-matched health controls were recruited. Region-of-interest (ROI)-based resting-state functional connectivity analysis and Tract-Based Spatial Statistics (TBSS) were performed on 30 patients and 30 controls, and 24 patients and 29 controls, respectively. The Pearson correlation was performed between the imaging measures and the Stroop performance and scores of the Positive and Negative Syndrome Scale (PANSS), respectively.

Results

Patients with schizophrenia showed significantly abnormal in the functional connectivity and its hemispheric asymmetry of the ACC-cd with multiple brain areas, e.g., decreased positive connectivity with the bilateral putamen and caudate, increased negative connectivity with the left posterior cingulated cortex (PCC), increased asymmetry of connectivity strength with the contralateral inferior frontal gyrus (IFG). The FA of the right anterior cingulum was significantly decreased in patients group (p = 0.014). The abnormal functional and structural connectivity of ACC-cd were correlated with Stroop performance and the severity of the symptoms in patients.

Conclusions

Our results suggested that the abnormal connectivity of the ACC-cd might play a role in the cognitive impairment and clinical symptoms in schizophrenia.     

Serum Acylated Ghrelin Concentrations in Response to Short-Term Overfeeding in Normal Weight,Overweight, and Obese Men

Background

Ghrelin, an orexigenic gut hormone secreted primarily from the stomach, is involved in energy homeostasis. However, little data is available regarding its response to energy surplus and the development of human obesity.

Objective

The present study investigated the response of circulating acylated ghrelin to a 7-day positive energy challenge.

Design

A total of 68 healthy young men were overfed 70% more calories than required, for 1-week. Subjects were classified based on percent body fat (measured by dual-energy X-ray absorptiometry) as normal weight, overweight, and obese. Serum acylated ghrelin concentration was measured before and after the positive energy challenge. Additionally, the relationship between acylated ghrelin and obesity-related phenotypes including weight, body mass index, percent body fat, cholesterol, HDL-c, LDL-c, glucose, insulin and homeostasis model assessment of insulin resistance and β-cell function at baseline and change due to overfeeding, were assessed.

Results

Contrary to our expectations, serum acylated ghrelin was significantly increased in response to overfeeding and the increase was independent of obesity status. There was no significant difference in fasting acylated ghrelin between normal weight, overweight, and obese men at baseline. Acylated ghrelin was negatively correlated with weight and BMI for normal weight and with BMI in overweight men. Also ghrelin was correlated with change in weight and BMI in overweight (negative relationship) and obese (positive relationship) groups.

Conclusion

Our results showed that circulating acylated ghrelin was increased after a 7-day positive energy challenge regardless of adiposity status. However, acylated ghrelin was correlated with change in weight and BMI in opposing directions, in overweight and obese subjects respectively, thus dependent on obesity status.     

Natural Killer Cells Are Characterized by the Concomitantly Increased Interferon-γ and Cytotoxicity in Acute Resolved Hepatitis B Patients

Natural killer (NK) cells are abundant in the liver and have been implicated in inducing hepatocellular damage in patients with chronic hepatitis B virus (HBV) infection. However, the role of NK cells in acute HBV infection remains to be elucidated. We comprehensively characterized NK cells and investigated their roles in HBV clearance and liver pathology in 19 chronic hepatitis B (CHB) patients and 21 acute hepatitis B (AHB) patients as well as 16 healthy subjects. It was found that NKp46⁺ NK cells were enriched in the livers of AHB and CHB patients. We further found that peripheral NK cells from AHB patients expressed higher levels of activation receptors and lower levels of inhibitory receptors than those from CHB patients and HC subjects, thus displaying the increased cytolytic activity and interferon-γ production. NK cell activation levels were also correlated positively with serum alanine aminotransferase levels and negatively with plasma HBV DNA levels in AHB patients, which is further confirmed by the longitudinal follow-up of AHB patients. Serum pro-inflammatory cytokine and chemokine levels were also increased in AHB patients as compared with CHB and HC subjects. Thus, the concomitantly increased interferon-γ and cytotoxicity of NK cells were associated with liver injury and viral clearance in AHB patients.