[Research Progress of microRNA-7/124/155 in Parkinson's Disease]

Parkinson's disease(PD)is the second most common neurodegenerative disease after Alzheimer's disease,with high morbidity and high disability rate.Since the early symptoms of PD are not typical and often similar to those of normal aging or other diseases.It is easy to missed diagnosis and misdiagnosis,which seriously affects the diagnosis and treatment of this disease and aggravetes the burden on the patients' life.MicroRNAs(miRNA)are a class of endogenous non-coding RNAs that are involved in post-transcriptional regulation by binding to target messenger RNAs(mRNA).They are highly conserved,short,easy to obtain,and can stably exist in peripheral body fluids.They have been used as biomarkers for a variety of diseases.Recent studies have demonstrated that miRNA play an important role in the development of PD.This paper reviews the recent research progress of miR-7/124/155,three mature miRNA in PD,aiming to provide reference for clarifying the pathogenesis and guiding the diagnosis and treatment of PD.

Upregulated DNA Damage-Linked Biomarkers in Parkinson's Disease Model Mice

SUMMARY STATEMENT

The present study examined expression of DNA damage markers in VMAT2 Lo PD model mice. The results demonstrate there is a significant increase in these DNA damage markers mostly in the brain regions of 18- and 23-month-old model mice, indicating oxidative stress-induced DNA lesion is an important pathologic feature of this mouse model.

Exploration and Practice of Electronic, Networked and Intelligent Methods for Basic Medical Science Education to Develop Pathology Interest

Introduction/Objective

In response to the sudden COVID-19 pandemic, the Chinese government has restricted student visas for international students as part of an emergency "zero COVID" plan. As a result of these border closures, most international students enrolled in Chinese medical universities have not returned to campus for more than 2.5 years and have continued their medical education online. Basic medical science study has continued relatively smoothly compared to clinical apprenticeships, which focus more on clinical traineeship and practice. How to turn the crisis caused by the pandemic into an opportunity to improve the level of basic medical science education and level of pathology interest in our school is the topic explored in this paper.

Methods/Case Report

The methods proposed in this study include the intelligence of artificial intelligence technology and adaptive teaching tools for teaching students in accordance with their aptitude, interactive microscopic slides and gross pathology recognition methods based on computer graphics technology, and Internet-based group learning and large group discussions. All the advantages of traditional classroom teaching are therefore included and some overcome the shortcomings of traditional classroom teaching.

Results (if a Case Study enter NA)

Grades in 2019-2020 school year basic medical science courses were obtained. In this school year, the first semester was traditional education on campus and the second semester was online using the method described in this paper. Second semester grades were 17.2% higher than the first. USMLE Step 1 performance was another measured outcome because it focuses on basic science and pathology. A good outcome on this exam was obtained and the teaching method proposed in this paper is verified.

Conclusion

The author is preparing to expand the sample size to further verify, improve, and perfect the method proposed in this paper, so as to promote the depth and breadth of basic medical education and continuing success from education into success in pathology careers.

[Pathogenic detection and molecular tracing of a bacillary dysentery outbreak by Shigella sonnei in Huainan city]

Objective: To understand the virulence gene and drug resistance profile of Shigella sonnei outbreak in Huainan city, and conduct pathogenic traceability analysis. Methods: Water samples and feces related to an infectious diarrhea outbreak in Huainan city in August 2020 were collected for multiple pathogen detection. Virulence gene, drug sensitivity, pulse-field gel electrophoresis and whole genome sequencing of Shigella isolates were analyzed respectively. Results: 38 strains of Shigella sonnei were detected in 56 samples of mucilage feces with a positive rate 67.86%, and all serotypes were Shigella sonnei Phase I. Three strains of Shigella sonnei were detected by fluorescence PCR in the Gram-negative (GN) bacterial enrichment solution of terminal water and well water. Virulence genes were ipaH positive (38), ipaH/ial (31) and ipaH/ial/sen positive (1), respectively. The drug resistance spectrum showed that 9 of 14 antibiotics were 100% resistant, and only imipenem, chloramphenicol, ceftazidime and ciprofloxacin were effective drugs. XbaⅠ restriction enzyme map type of 36 isolates was completely consistent, and the ST type analysis of 3 strains was ST152. Whole genome sequencing and analysis verified that the outbreak was caused by a single clonal group of strains, and revealed that the isolates of the outbreak were clustered into a large cluster with 3 Chinese strains and 1 Korean strain in the database, far away from the strains of other countries. Conclusion: The outbreak is caused by a single clone of Shigella sonnei, which are low virulence strains and have multiple drug resistance.

Effects of Manipulation of Noradrenergic Activities on the Expression of Dopaminergic Phenotypes in Aged Rat Brains

This study investigated the effects of the pharmacological manipulation of noradrenergic activities on dopaminergic phenotypes in aged rats. Results showed that the administration of L-threo-3,4-dihydroxyphenylserine (L-DOPS) for 21 days significantly increased the expression of tyrosine hydroxylase (TH) and dopamine transporter (DAT) in the striatum and substantia nigra (SN) of 23-month-old rats. Furthermore, this treatment significantly increased norepinephrine/DA concentrations in the striatum and caused a deficit of sensorimotor gating as measured by prepulse inhibition (PPI). Next, old rats were injected with the α2-adrenoceptor antagonist 2-methoxy idazoxan or β2-adrenoceptor agonist salmeterol for 21 days. Both drugs produced similar changes of TH and DAT in the striatum and SN. Moreover, treatments with L-DOPS, 2-methoxy idazoxan, or salmeterol significantly increased the protein levels of phosphorylated Akt in rat striatum and SN. However, although a combination of 2-methoxy idazoxan and salmeterol resulted in a deficit of PPI in these rats, the administration of 2-methoxy idazoxan alone showed an opposite behavioral change. The in vitro experiments revealed that treatments with norepinephrine markedly increased mRNAs and proteins of ATF2 and CBP/p300 and reduced mRNA and proteins of HDAC2 and HDAC5 in MN9D cells. A ChIP assay showed that norepinephrine significantly increased CBP/p300 binding or reduced HDAC2 and HDAC5 binding on the TH promoter. The present results indicate that facilitating noradrenergic activity in the brain can improve the functions of dopaminergic neurons in aged animals. While this improvement may have biochemically therapeutic indication for the status involving the degeneration of dopaminergic neurons, it may not definitely include behavioral improvements, as indicated by using 2-methoxy idazoxan only.

Restoration of Noradrenergic Function in Parkinson's Disease Model Mice

Dysfunction of the central noradrenergic and dopaminergic systems is the primary neurobiological characteristic of Parkinson’s disease (PD). Importantly, neuronal loss in the locus coeruleus (LC) that occurs in early stages of PD may accelerate progressive loss of dopaminergic neurons. Therefore, restoring the activity and function of the deficient noradrenergic system may be an important therapeutic strategy for early PD. In the present study, the lentiviral constructions of transcription factors Phox2a/2b, Hand2 and Gata3, either alone or in combination, were microinjected into the LC region of the PD model VMAT2 Lo mice at 12 and 18 month age. Biochemical analysis showed that microinjection of lentiviral expression cassettes into the LC significantly increased mRNA levels of Phox2a, and Phox2b, which were accompanied by parallel increases of mRNA and proteins of dopamine β-hydroxylase (DBH) and tyrosine hydroxylase (TH) in the LC. Furthermore, there was considerable enhancement of DBH protein levels in the frontal cortex and hippocampus, as well as enhanced TH protein levels in the striatum and substantia nigra. Moreover, these manipulations profoundly increased norepinephrine and dopamine concentrations in the striatum, which was followed by a remarkable improvement of the spatial memory and locomotor behavior. These results reveal that over-expression of these transcription factors in the LC improves noradrenergic and dopaminergic activities and functions in this rodent model of PD. It provides the necessary groundwork for the development of gene therapies of PD, and expands our understanding of the link between the LC-norepinephrine and dopamine systems during the progression of PD.

Transcription Factors Phox2a/2b Upregulate Expression of Noradrenergic and Dopaminergic Phenotypes in Aged Rat Brains

The present study investigated the effects of forced overexpression of Phox2a/2b, two transcription factors, in the locus coeruleus (LC) of aged rats on noradrenergic and dopaminergic phenotypes in brains. Results showed that a significant increase in Phox2a/2b mRNA levels in the LC region was paralleled by marked enhancement in expression of DBH and TH per se. Furthermore, similar increases in TH protein levels were observed in the substantial nigra and striatum, as well as in the hippocampus and frontal cortex. Overexpression of Phox2 genes also significantly increased BrdU-positive cells in the hippocampal dentate gyrus and NE levels in the striatum. Moreover, this manipulation significantly improved the cognition behavior. The in vitro experiments revealed that norepinephrine treatments may increase the transcription of TH gene through the epigenetic action on the TH promoter. The results indicate that Phox2 genes may play an important role in improving the function of the noradrenergic and dopaminergic neurons in aged animals, and regulation of Phox2 gene expression may have therapeutic utility in aging or disorders involving degeneration of noradrenergic neurons.

[CD7 expression and its prognostic significance in acute myeloid leukemia patients with wild-type or mutant CEBPA]

目的

分析CD7在初治急性髓系白血病（AML）患者中的表达和预后价值，进一步探讨CD7表达情况与CEBPA突变的相关性，明确其在CEBPA野生型和突变型AML患者中与预后的关系。

方法

回顾性分析2010年1月至2016年12月收治的298例初治AML患者（除外M₃亚型）的临床资料，在全部患者以及CEBPA野生型和突变型组中，分别比较CD7阳性（CD7⁺）和CD7阴性（CD7⁻）患者的临床特征及预后差异，并联合CD7表达情况和CEBPA突变状态初步建立新的危险分层模型。

结果

在CD7⁺组中，CEBPA单位点和双位点突变的发生率分别为10.1%和33.9%，显著高于CD7⁻组（5.3%和4.2%），差异具有统计学意义（P=0.000）。在CEBPA野生型患者中，CD7⁺组患者相较CD7⁻组患者完全缓解率低（P=0.001）、复发率高（P=0.023），而两组总生存（OS）期和无病生存（DFS）期差异无统计学意义（P值均>0.05）；在CEBPA突变患者中，CD7⁺组显示有更长的OS期（P=0.019）和DFS期（P=0.010）。根据CD7表达和CEBPA突变与否将AML患者分为三个亚组：CD7⁺伴CEBPA突变组、CD7⁻组和CD7⁺伴CEBPA野生型组。三组患者的3年OS率分别为80.2%、48.0%和30.6%（P<0.001），3年的DFS率分别为74.1%、37.4%和22.2%（P<0.001）。

结论

CD7⁺组中CEBPA突变率显著高于CD7⁻组，CD7⁺在CEBPA野生型组和突变组AML中存在截然相反的预后意义。根据CD7表达情况和CEBPA突变与否建立新的危险分层模型，有助于指导临床个体化治疗。

Critical Role of Oxidatively Damaged DNA in Selective Noradrenergic Vulnerability

An important pathology in Parkinson's disease (PD) is the earlier and more severe degeneration of noradrenergic neurons in the locus coeruleus (LC) than dopaminergic neurons in the substantia nigra. However, the basis of such selective vulnerability to insults remains obscure. Using noradrenergic and dopaminergic cell lines, as well as primary neuronal cultures from rat LC and ventral mesencephalon (VM), the present study compared oxidative DNA damage response markers after exposure of these cells to hydrogen peroxide (H₂O₂). The results showed that H₂O₂ treatment resulted in more severe cell death in noradrenergic cell lines SK-N-BE(2)-M17 and PC12 than dopaminergic MN9D cells. Furthermore, there were higher levels of oxidative DNA damage response markers in noradrenergic cells and primary neuronal cultures from the LC than dopaminergic cells and primary cultures from the VM. It included increased tail moments and tail lengths in Comet assay, and increased protein levels of phosphor-p53 and γ-H2AX after treatments with H₂O₂. Consistent with these measurements, exposure of SK-N-BE(2)-M17 cells to H₂O₂ resulted in higher levels of reactive oxygen species (ROS). Further experiments showed that exposure of SK-N-BE(2)-M17 cells to H₂O₂ caused an increased level of noradrenergic transporter, reduced protein levels of copper transporter (Ctr1) and 8-oxoGua DNA glycosylase, as well as amplified levels of Ca_v1.2 and Ca_v1.3 expression. Taken together, these experiments indicated that noradrenergic neuronal cells seem to be more vulnerable to oxidative damage than dopaminergic neurons, which may be related to the intrinsic characteristics of noradrenergic neuronal cells.

[Clinical-pathological analysis of 71 cases of dermatosis papulosa nigra of Han Chinese people]

Objective: To analyze and summarize the clinical-pathological features of dermatosis papulosa nigra of Han Chinese people. Methods: We collected 71 cases of dermatosis papulosa nigra in the Third people's Hospital of Hangzhou Affiliated to Zhejiang Chinese Medical University of Department of Dermatology from January 2010 to January 2019 which were confirmed clinically and pathologically. The clinical and histopathological data of all patients were analyzed and summarized, and relevant literature were reviewed. Results: Among the 71 patients, 51 were female and 25 were male, their average age was (44±13) years, the average age of onset was (39±14) years, and the average time of diagnosis was (65±51) months. The lesions were multiple dark brown papules with smooth surface, and mostly distributed in the chest and abdomen, 46 cases (64.8%), followed by the back and neck. The mean diameter of the lesions was (1.76±0.99) mm. Meanwhile, the initial onset of pruritus was observed in 15 patients. The pathological features of all lesions were similar to seborrheic keratosis. According to pathological classification, there were 49 (69.0%) cases of the acanthotic type, 11(15.5%) cases of the hyperkeratotic type, 6 (8.5%) cases of spiroid type, 4 (5.6%) cases of irritated type, and 1 (1.4%) case of clonal type. Epidermal pigmentation and/or dermal papillary pigmented granules were observed in 56 cases (78.9%), of which 46 cases (64.8%) had basal layer pigmentation. In addition, inflammatory cell infiltration was found in the superficial dermis of lesions of 10 patients (14.1%) with symptom of itching. Conclusion: Dermatosis papulosa nigra of Han Chinese people has some unique clinical and pathological features.

Norepinephrine upregulates the expression of tyrosine hydroxylase and protects dopaminegic neurons against 6-hydrodopamine toxicity

As a classic neurotransmitter in the brain, norepinephrine (NE) also is an important modulator to other neuronal systems. Using primary cultures from rat ventral mesencephalon (VM) and dopaminergic cell line MN9D, the present study examined the neuroprotective effects of NE and its effects on the expression of tyrosine hydroxylase (TH). The results showed that NE protected both VM cultures and MN9D cells against 6-hydroxydopamine-caused apoptosis, with possible involvement of adrenal receptors. In addition, treatment with NE upregulated TH protein levels in dose- and time-dependent manner. Further experiments to investigate the potential mechanisms underlying this NE-induced upregulation of TH demonstrated a marked increase in protein levels of the brain-derived neurotrophic factor (BDNF) and the phosphorylated extracellular signal-regulated protein kinase 1 and 2 (pERK1/2) in VM cultures treated with NE. In MN9D cells, a significantly increase of TH and pERK1/2 protein levels were observed after their transfection with BDNF cDNA or exposure to BDNF peptides. Treatment of VM cultures with K252a, an antagonist of the tropomyosin-related kinase B, blocked the upregulatory effects of NE on TH, BDNF and pERK1/2. Administration of MEK1 & MEK2 inhibitors also reversed NE-induced upregulation of TH and pERK1/2. Moreover, ChIP assay showed that treatment with NE or BDNF increased H4 acetylation in the TH promoter. These results suggest that the neuroprotection and modulation of NE on dopaminergic neurons are mediated via BDNF and MAPK/ERK pathways, as well as through epigenetic histone modification, which may have implications for the improvement of therapeutic strategies for Parkinson's disease.

Altered Expression of Phox2 Transcription Factors in the Locus Coeruleus in Major Depressive Disorder Mimicked by Chronic Stress and Corticosterone Treatment In Vivo and In Vitro

Phox2a and Phox2b are two homeodomain transcription factors playing a pivotal role in the development of noradrenergic neurons during the embryonic period. However, their expression and function in adulthood remain to be elucidated. Using human postmortem brain tissues, rat stress models and cultured cells, this study aimed to examine the alteration of Phox2a and Phox2b expression. The results show that Phox2a and Phox2b are normally expressed in the human locus coeruleus (LC) in adulthood. Furthermore, the levels of Phox2a protein and mRNA and protein levels of Phox2b were significantly elevated in the LC of brain donors that suffered from the major depressive disorder, as compared to age-matched and psychiatrically normal control donors. Fischer 344 rats subjected to chronic social defeat showed higher mRNA and protein levels of Phox2a and Phox2b in the LC, as compared to non-stressed control rats. In rats chronically administered oral corticosterone, mRNA and protein levels of Phox2b, but not Phox2a, in the LC were significantly increased. In addition, the corticosterone-induced increase in Phox2b protein was reversed by simultaneous treatment with either mifepristone or spironolactone. Exposing SH-SY5Y cells to corticosterone significantly increased expression of Phox2a and Phox2b, which was blocked by corticosteroid receptor antagonists. Taken together, these experiments reveal that Phox2 genes are expressed throughout the lifetime in the LC of humans and Fischer 344 rats. Alterations in their expression may play a role in major depressive disorder and possibly other stress-related disorders through their modulatory effects on the noradrenergic phenotype.

Recognition of Core- and Polymerase-derived immunogenic peptides included in novel therapeutic vaccine by T cells from Chinese chronic hepatitis B patients

Chronic hepatitis B (CHB) is one of the major public health challenges in the world. Due to a strong interplay between specific T-cell immunity and elimination of hepatitis B virus (HBV), efforts to develop novel immunotherapeutics are gaining attention. TG1050, a novel immunotherapy, has shown efficacy in an animal study. To support the clinical development of TG1050 in China, specific immunity to the fusion antigens of TG1050 was assessed in Chinese patients. One hundred and thirty subjects were divided into three groups as CHB patients, HBV spontaneous resolvers, and CHB patients with HBsAg loss after antiviral treatment. HBV-specific T-cell responses to pools of HBV Core or Polymerase genotype D peptides included in TG1050 were evaluated. HBV Core- or Polymerase-specific cells were detected in peripheral blood mononuclear cells (PBMCs) from the different cohorts. The frequencies and intensities of HBV Core-specific immune responses were significantly lower in CHB patients than in HBsAg loss subjects. In CHB patients, a dominant pool derived from Polymerase (Pol1) was the most immunogenic. CHB patients with low viral loads (<10⁶ IU/mL) were more likely to have a positive response specific to the Core peptide pool. Overall, genotype D-derived peptides included in TG1050 could raise broad and functional T-cell responses in PBMCs from Chinese CHB patients infected with genotype B/C isolates. Core-specific immunogenic domains appeared as "hot spots" with the capacity to differentiate between CHB vs HBsAg loss subjects. These observations support the extended application and associated immune monitoring of TG1050 in China.

[The advances in research on precisely inducing retinal ganglion cells from stem cells]

The injury and repair of retinal neurons is a common scientific problem in the occurrence, development and prognosis of neuronal visual impairment. Transplant of retinal ganglion cells (RGCs) differentiated from stem cells opens a new avenue for treatment of glaucoma and optic neuronal degenerative diseases. For the goal to explore the optimal method for RGCs replacement, this review summarizes the current information regarding the classification and application of stem cells, the growth characteristics of RGCs and the precise methods to induce RGCs, and discusses some important issues that need resolving and are related to RGCs transplantation. It is hoped that this article will provide useful theoretical basis for the research of this field. (Chin J Ophthalmol, 2017, 53: 381-385).

[Workplace social capital and intention to stay among Chinese nurses: a structural equation model]

Objective: To explore a model that workplace social capital is associated with intention to stay (ITS) in the nursing profession and that this association is partially mediated by organizational commitment, job satisfaction, and job stress among Chinese nurses. Methods: A cross-sectional, observationalstudy was conducted in Shanghai, China between September and December 2014. Two thousandforty-two nurses from 23 healthcare organizations were recruited for the current study using a two-stage sampling process.Intention to stay, workplace social capital, job satisfaction, organizational commitment, and job stress was measured by validated scale. Measured variable path analysis (MVPA) was used to test their hypothesized relationships. Results: There were significant positive direct effects from workplace social capital (β=0.11, P<0.01) , organizational commitment (β=0.81, P<0.01) and job satisfaction (β=0.03, P<0.01) to ITS, and a negative direct effects from job strain to ITS (β=-0.03, P<0.01) . The model explained 84% of the variability in ITS. Additionally, workplace social capital had significant positive direct effects on organizational commitment (β=0.65, P<0.01) , job satisfaction (β=0.44, P<0.01) and negative direct effects on job strain (β=-0.35, P<0.01) . The indirect effect of social capital to ITS was 0.55. Job satisfaction was positively associated with organizational commitment (r=0.47, P<0.01) , and negtively associated with job stress (r=-0.12, P<0.01) . Job stress was negtively associated with organizational commitment (r=-0.20, P<0.01) . Conclusion: This study suggests that greater workplace social capital may lead to higher ITS in nursing primarily by increasing commitment to the nursing occupation and their job satisfaction and by reducing their sense of job stress.

[Inhibitory effect of quercetin on the biofilm formation of Streptococcus mutans]

OBJECTIVE

To observe the inhibitory effect of quercetin on the biofilm formation of Streptococcus mutans(Sm), to preliminarily reveal the possible underlying mechanisms, and to evaluate the cytotoxicity of quercetion to human dental pulp cells so as to provide the theoretical basis for the application of quercetin in oral biomaterials.

METHODS

Quercetin storage solution was diluted to 0, 3.125, 6.25, 12.5, 25, 50, 100, 200, 400 and 800 mg/L, and added into Sm medium for 4 h and 24 h, crystal violet staining was used to evaluate the biofilm volume. In subsequent detections, three groups were set: control(0 mg/L), 200 mg/L quercetin and 400 mg/L quercetin. Confocal laser scanning microscopy was used to observe the morphology of the biofilm; qPCR for gtfB, gtfC, comD, comE, and luxS were assessed to preliminarily investigate the mechanisms. Finally, the methyl thiazolyl tetrazolium(MTT)test using human dental pulp cells was used to investigate cytotoxicity.

RESULTS

Quercetin could significantly inhibit up to(86.16±0.45)% of the biofilm formation of Sm(Compared with the control group P=0.00)and effectively removed(43.04±0.53)% of the mature biofilm(Compared with the control group P=0.00). Confocal laser scanning microscopy photographs showed that after co-incubated for 24 h, the dense biofilm structures of the experimental group were destroyed by quercetin both at 200 mg/L and 400 mg/L. Quercetin suppressedover 50% of the expression of gtfB, gtfC, comD, comE(compared with the control group P<0.05)and promoted the expression of luxS up to 2.18 ± 0.24 and 2.84 ± 0.26 after 4 h and 24 h, respectively(compared with the control group P<0.05). Quercetin also exhibited acceptable compatibility for human dental pulp cells.

CONCLUSIONS

Quercetin could effectively reduce the biofilm formation of Sm by inhibiting the expression of the related genes, and exhibited no cytotoxicity for human dental pulp cells. Quercetin has good potential to be applied in oral biological materials.

MicroRNAs 29b and 181a down-regulate the expression of the norepinephrine transporter and glucocorticoid receptors in PC12 cells

MicroRNAs are short non-coding RNAs that provide global regulation of gene expression at the post-transcriptional level. Such regulation has been found to play a role in stress-induced epigenetic responses in the brain. The norepinephrine transporter (NET) and glucocorticoid receptors are closely related to the homeostatic integration and regulation after stress. Our previous studies demonstrated that NET mRNA and protein levels in rats are regulated by chronic stress and by administration of corticosterone, which is mediated through glucocorticoid receptors. Whether miRNAs are intermediaries in the regulation of these proteins remains to be elucidated. This study was undertaken to determine possible regulatory effects of miRNAs on the expression of NET and glucocorticoid receptors in the noradrenergic neuronal cell line. Using computational target prediction, we identified several candidate miRNAs potentially targeting NET and glucocorticoid receptors. Western blot results showed that over-expression of miR-181a and miR-29b significantly repressed protein levels of NET, which is accompanied by a reduced [³ H] norepinephrine uptake, and glucocorticoid receptors in PC12 cells. Luciferase reporter assays verified that both miR-181a and miR-29b bind the 3'UTR of mRNA of NET and glucocorticoid receptors. Furthermore, exposure of PC12 cells to corticosterone markedly reduced the endogenous levels of miR-29b, which was not reversed by the application of glucocorticoid receptor antagonist mifepristone. These observations indicate that miR-181a and miR-29b can function as the negative regulators of NET and glucocorticoid receptor translation in vitro. This regulatory effect may be related to stress-induced up-regulation of the noradrenergic phenotype, a phenomenon observed in stress models and depressive patients. This study demonstrated that miR-29b and miR-181a, two short non-coding RNAs that provide global regulation of gene expression, markedly repressed protein levels of norepinephrine (NE) transporter and glucocorticoid receptor (GR), as well as NE uptake by binding the 3'UTR of their mRNAs in PC12 cells. Also, exposure of cells to corticosterone significantly reduced miR-29b levels through a GR-independent way.

Corticotropin releasing factor up-regulates the expression and function of norepinephrine transporter in SK-N-BE (2) M17 cells

Corticotropin releasing factor (CRF) has been implicated to act as a neurotransmitter or modulator in central nervous activation during stress. In this study, we examined the regulatory effect of CRF on the expression and function of the norepinephrine transporter (NET) in vitro. SK-N-BE (2) M17 cells were exposed to different concentrations of CRF for different periods. Results showed that exposure of cells to CRF significantly increased mRNA and protein levels of NET in a concentration- and time-dependent manner. The CRF-induced increase in NET expression was mimicked by agonists of either CRF receptor 1 or 2. Furthermore, similar CRF treatments induced a parallel increase in the uptake of [(3) H] norepinephrine. Both increased expression and function of NET caused by CRF were abolished by simultaneous administration of CRF receptor antagonists, indicating a mediation by CRF receptors. However, there was no additive effect for the combination of both receptor antagonists. Chromatin immunoprecipitation assays confirm an increased acetylation of histone H3 on the NET promoter following treatment with CRF. Taken together, this study demonstrates that CRF up-regulates the expression and function of NET in vitro. This regulation is mediated through CRF receptors and an epigenetic mechanism related to histone acetylation may be involved. This CRF-induced regulation on NET expression and function may play a role in development of stress-related depression and anxiety. This study demonstrated that corticotropin release factor (CRF) up-regulated the expression and function of norepinephrine transporter (NET) in a concentration- and time-dependent manner, through activation of CRF receptors and possible histone acetylation in NET promoter. The results indicate that their interaction may play an important role in stress-related physiological and pathological status.

Impact of adherence to GOLD guidelines on 6-minute walk distance, MRC dyspnea scale score, lung function decline, quality of life, and quality-adjusted life years in a Shanghai suburb

We performed a 1-year cluster-randomized field trial to assess the effect of standardized management of chronic obstructive pulmonary disease (COPD) on lung function and quality of life (QOL) measures in patients in China. We used the Global Initiative for Chronic Obstructive Lung Disease (GOLD) treatment guidelines and assessed indexes including pulmonary function, QOL, quality-adjusted life years (QALY), Medical Research Council (MRC) dyspnea scale, 6-min walk distance (6-MWD), number of emergency visits, and frequency of hospitalization. Of a total of 711 patients with chronic cough and asthma, 132 were diagnosed as having COPD and 102 participated in this study [intervention group (N = 47); control group (N = 55)]. We found that adherence to GOLD guidelines had a perceivable impact on 6-MWD, MRC dyspnea scale score, and QOL. The average QALY increased by 1.42/person/year in the intervention group, but declined by 0.95/person/year in the control group. We conclude that standardized management improves disease severity, QOL, and QALY in COPD patients when treatment protocols adhere to GOLD guidelines.

Effects of Antidepressants on DSP4/CPT-Induced DNA Damage Response in Neuroblastoma SH-SY5Y Cells

DNA damage is a form of cell stress and injury. Increased systemic DNA damage is related to the pathogenic development of neurodegenerative diseases. Depression occurs in a relatively high percentage of patients suffering from degenerative diseases, for whom antidepressants are often used to relieve depressive symptoms. However, few studies have attempted to elucidate why different groups of antidepressants have similar effects on relieving symptoms of depression. Previously, we demonstrated that neurotoxins N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4)- and camptothecin (CPT) induced the DNA damage response in SH-SY5Y cells, and DSP4 caused cell cycle arrest which was predominately in the S-phase. The present study shows that CPT treatment also resulted in similar cell cycle arrest. Some classic antidepressants could reduce the DNA damage response induced by DSP4 or CPT in SH-SY5Y cells. Cell viability examination demonstrated that both DSP4 and CPT caused cell death, which was prevented by spontaneous administration of some tested antidepressants. Flow cytometric analysis demonstrated that a majority of the tested antidepressants protect cells from being arrested in S-phase. These results suggest that blocking the DNA damage response may be an important pharmacologic characteristic of antidepressants. Exploring the underlying mechanisms may allow for advances in the effort to improve therapeutic strategies for depression appearing in degenerative and psychiatric diseases.

Neurotoxin-induced DNA damage is persistent in SH-SY5Y cells and LC neurons

Degeneration of the noradrenergic neurons has been reported in the brain of patients suffering from neurodegenerative diseases. However, their pathological characteristics during the neurodegenerative course and underlying mechanisms remain to be elucidated. In the present study, we used the neurotoxin camptothecin (CPT) to induce the DNA damage response in neuroblastoma SH-SY5Y cells, normal fibroblast cells, and primarily cultured locus coeruleus (LC) and raphe neurons to examine cellular responses and repair capabilities after neurotoxin exposure. To our knowledge, the present study is the first to show that noradrenergic SH-SY5Y cells are more sensitive to CPT-induced DNA damage and deficient in DNA repair, as compared to fibroblast cells. Furthermore, similar to SH-SY5Y cells, primarily cultured LC neurons are more sensitive to CPT-induced DNA damage and show a deficiency in repairing this damage. Moreover, while N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) exposure also results in DNA damage in cultured LC neurons, neither CPT nor DSP4 induce DNA damage in neuronal cultures from the raphe nuclei. Taken together, noradrenergic SH-SY5Y cells and LC neurons are sensitive to CPT-induced DNA damage and exhibit a repair deficiency, providing a mechanistic explanation for the pathological characteristics of LC degeneration when facing endogenous and environmental DNA-damaging insults in vivo.

Corticosterone administration up-regulated expression of norepinephrine transporter and dopamine β-hydroxylase in rat locus coeruleus and its terminal regions

Stress has been reported to activate the locus coeruleus (LC)-noradrenergic system. In this study, corticosterone (CORT) was orally administrated to rats for 21 days to mimic stress status. In situ hybridization measurements showed that CORT ingestion significantly increased mRNA levels of norepinephrine transporter (NET) and dopamine β-hydroxylase (DBH) in the LC region. Immunofluorescence staining and western blotting revealed that CORT treatment also increased protein levels of NET and DBH in the LC, as well as NET protein levels in the hippocampus, the frontal cortex and the amygdala. However, CORT-induced increase in DBH protein levels only appeared in the hippocampus and the amygdala. Elevated NET and DBH expression in most of these areas (except for NET protein levels in the LC) was abolished by simultaneous treatment with combination of corticosteroid receptor antagonist mifepristone and spironolactone (s.c. for 21 days). Also, treatment with mifepristone alone prevented CORT-induced increases of NET expression and DBH protein levels in the LC. In addition, behavioral tasks showed that CORT ingestion facilitated escape in avoidance trials using an elevated T-maze, but interestingly, there was no significant effect on the escape trial. Corticosteroid receptor antagonists failed to counteract this response in CORT-treated rats. In the open-field task, CORT treatment resulted in less activity in a defined central zone compared to controls and corticosteroid receptor antagonist treatment alleviated this increase. In conclusion, this study demonstrates that chronic exposure to CORT results in a phenotype that mimics stress-induced alteration of noradrenergic phenotypes, but the effects on behavior are task dependent. As the sucrose consumption test strongly suggests CORT ingestion-induced depression-like behavior, further elucidation of underlying mechanisms may improve our understanding of the correlation between stress and the development of depression.

Mutational analysis of positively charged residues in the N-terminal region of the class IIa bacteriocin pediocin PA-1

The significance of positively charged residues for the target cell binding of pediocin PA-1 bacteriocins was studied by site-directed mutagenesis. Most of the charged residues are located in the N-terminal half of the peptide, which is thought to mediate the initial binding of these bacteriocins to their target cells through electrostatic interactions. Mutated peptides in which the positively charged residues were substituted or increased in number were constructed, and some of these peptides exhibited a twofold increase in the bacteriostatic activity. The greatest enhancement was achieved by introduced the positive charges at position 13, their results show the benefits of introducing an additional cationic residue within this patch in the middle of the N-terminal half of pediocin PA-1 bacteriocins. Thus, the presence of additional cationic residues in the N-terminal half influenced the electrostatic binding of this bacteriocin to its target cells and increased the potency of the peptide on the potency of Micrococcus luteus and Staphylococcus aureus.

SIGNIFICANCE AND IMPACT OF THE STUDY

No previous work has systematically examined the N-terminal cationic residues of the pediocin PA-1 for their functional importance or redundancy. In this study, we examined the structure-function relationships of pediocin PA-1 by site-directed mutagenesis. Mutated peptides in which the positively charged residues were substituted and increased in number exhibited a twofold increase in the bacteriostatic activity. This study demonstrated the importance of the cationic patch in the N-terminal half of pediocin PA-1. The cationic residues influenced the electrostatic binding of the bacteriocin to the target cells and had a greater effect on the potency of the peptide towards Micrococcus luteus and Staphylococcus aureus.

Effects of DSP4 on the noradrenergic phenotypes and its potential molecular mechanisms in SH-SY5Y cells

Dopamine β-hydroxylase (DBH) and norepinephrine (NE) transporter (NET) are the noradrenergic phenotypes for their functional importance to noradrenergic neurons. It is known that in vivo N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) treatment induces degeneration of noradrenergic terminals by interacting with NET and depleting intracellular NE. However, DSP4's precise mechanism of action remains unclear. In this study various biochemical approaches were employed to test the hypothesis that DSP4 down-regulates the expression of DBH and NET, and to determine molecular mechanisms that may be involved. The results showed that treatment of SH-SY5Y neuroblastoma cells with DSP4 significantly decreased mRNA and protein levels of DBH and NET. DSP4-induced reduction of DBH mRNA and proteins, as well as NET proteins showed a time- and concentration-dependent manner. Flow cytometric analysis demonstrated that DSP4-treated cells were arrested predominantly in the S-phase, which was reversible. The arrest was confirmed by several DNA damage response markers (phosphorylation of H2AX and p53), suggesting that DSP4 causes replication stress which triggers cell cycle arrest via the S-phase checkpoints. Moreover, the comet assay verified that DSP4 induced single-strand DNA breaks. In summary, the present study demonstrated that DSP4 down-regulates the noradrenergic phenotypes, which may be mediated by its actions on DNA replication, leading to replication stress and cell cycle arrest. These action mechanisms of DSP4 may account for its degenerative consequence after systematic administration for animal models.

Chronic social defeat up-regulates expression of the serotonin transporter in rat dorsal raphe nucleus and projection regions in a glucocorticoid-dependent manner

Chronic stress and dysfunction of the serotonergic system in the brain have been considered two of the major risks for development of depression. In this study, adult Fischer 344 rats were subjected to a regimen of chronic social defeat (CSD). To mimic stressful conditions, some rats were not exposed to CSD, but instead treated with corticosterone (CORT) in oral solution while maintained in their home cage. Protein levels of the serotonin transporter (SERT) in the dorsal raphe nucleus (DRN), hippocampus, frontal cortex, and amygdala were examined by Western blotting or immunofluorescence staining. The results showed that CSD up-regulated SERT protein levels in the DRN, hippocampus, frontal cortex, and amygdala regions. This up-regulation was abolished or prevented by adrenalectomy, or treatment with antagonists of corticosteroid receptors mifepristone and spironolactone, alone or in combination. Similarly, up-regulated SERT protein levels in these brain regions were also observed in rats treated with oral CORT ingestion, which was analogously prevented by treatment with mifepristone and spironolactone. Furthermore, both CSD- and CORT-induced up-regulation of SERT protein levels in the DRN and three brain regions were attenuated by simultaneous treatment with fluoxetine, an antidepressant that specifically inhibits serotonin reuptake. The results indicate that up-regulation in SERT protein levels in the DRN and forebrain limbic structures caused by CSD regimen was mainly motivated by CORT through corticosteroid receptors. The present findings demonstrate that chronic stress is closely correlated with the serotonergic system by acting on the regulation of the SERT expression in the DRN and its projection regions, which may contribute to the development of depression.

Chronic social defeat up-regulates expression of norepinephrine transporter in rat brains

Stress has been reported to activate the locus coeruleus (LC)-noradrenergic system. However, the molecular link between chronic stress and noradrenergic neurons remains to be elucidated. In the present study adult Fischer 344 rats were subjected to a regimen of chronic social defeat (CSD) for 4weeks. Measurements by in situ hybridization and Western blotting showed that CSD significantly increased mRNA and protein levels of the norepinephrine transporter (NET) in the LC region and NET protein levels in the hippocampus, frontal cortex and amygdala. CSD-induced increases in NET expression were abolished by adrenalectomy or treatment with corticosteroid receptor antagonists, suggesting the involvement of corticosterone and corticosteroid receptors in this upregulation. Furthermore, protein levels of protein kinase A (PKA), protein kinase C (PKC), and phosphorylated cAMP-response element binding (pCREB) protein were significantly reduced in the LC and its terminal regions by the CSD paradigm. Similarly, these reduced protein levels caused by CSD were prevented by adrenalectomy. However, effects of corticosteroid receptor antagonists on CSD-induced down-regulation of PKA, PKC, and pCREB proteins were not consistent. While mifeprestone and spironolactone, either alone or in combination, totally abrogate CSD effects on these protein levels of PKA, PKC and pCREB in the LC and those in the hippocampus, frontal cortex and amygdala, their effects on PKA and PKC in the hippocampus, frontal cortex and amygdala were region-dependent. The present findings indicate a correlation between chronic stress and activation of the noradrenergic system. This correlation and CSD-induced alteration in signal transduction molecules may account for their critical effects on the development of symptoms of major depression.

Transcription factor Phox2 upregulates expression of norepinephrine transporter and dopamine β-hydroxylase in adult rat brains

Degeneration of the noradrenergic locus coeruleus (LC) in aging and neurodegenerative diseases is well documented. Slowing or reversing this effect may have therapeutic implications. Phox2a and Phox2b are homeodomain transcriptional factors that function as determinants of the noradrenergic phenotype during embryogenesis. In the present study, recombinant lentiviral eGFP-Phox2a and -Phox2b (vPhox2a and vPhox2b) were constructed to study the effects of Phox2a/2b over-expression on dopamine β-hydroxylase (DBH) and norepinephrine transporter (NET) levels in central noradrenergic neurons. Microinjection of vPhox2 into the LC of adult rats significantly increased Phox2 mRNA levels in the LC region. Over-expression of either Phox2a or Phox2b in the LC was paralleled by significant increases in mRNA and protein levels of DBH and NET in the LC. Similar increases in DBH and NET protein levels were observed in the hippocampus following vPhox2 microinjection. In the frontal cortex, only NET protein levels were significantly increased by vPhox2 microinjection. Over-expression of Phox2 genes resulted in a significant increase in BrdU-positive cells in the hippocampal dentate gyrus. The present study demonstrates an upregulatory effect of Phox2a and Phox2b on the expression of DBH and NET in noradrenergic neurons of rat brains, an effect not previously shown in adult animals. Phox2 genes may play an important role in maintaining the function of the noradrenergic neurons after birth, and regulation of Phox2 gene expression may have therapeutic utility in aging or disorders involving degeneration of noradrenergic neurons.

Dexamethasone-induced up-regulation of the human norepinephrine transporter involves the glucocorticoid receptor and increased binding of C/EBP-β to the proximal promoter of norepinephrine transporter

Previously, we have found glucocorticoids up-regulate norepinephrine (NE) transporter (NET) expression in vitro. However, the underlying transcriptional mechanism is poorly understood. In this study, the role of glucocorticoids on the transcriptional regulation of NET was investigated. Exposure of neuroblastoma SK-N-BE(2)M17 cells to dexamethasone (Dex) significantly increased NET mRNA and protein levels in a time- and dose-dependent manner. This effect was attenuated by glucocorticoid receptor (GR) antagonist mifepristone, suggesting that up-regulation of NET by Dex was mediated by the GR. In reporter gene assays, exposure of cells to Dex resulted in dose-dependent increases of luciferase activity that were also prevented by mifepristone. Serial deletions of the NET promoter delineated Dex-responsiveness to a -301 to -148 bp region containing a CCAAT/enhancer binding protein-β (C/EBP-β) response element. Co-immunoprecipitation experiments demonstrated that Dex treatment caused the interaction of the GR with C/EBP-β. Chromatin immunoprecipitation (ChIP) assay revealed that Dex exposure resulted in binding of both GR and C/EBP-β to the NET promoter. Further experiments showed that mutation of the C/EBP-β response element abrogated C/EBP-β- and GR-mediated transactivation of NET. These findings demonstrate that Dex-induced increase in NET expression is mediated by the GR via a non-conventional transcriptional mechanism involving interaction of C/EBP-β with a C/EBP-β response element.

Reserpine-induced reduction in norepinephrine transporter function requires catecholamine storage vesicles

Treatment of rats with reserpine, an inhibitor of the vesicular monoamine transporter (VMAT), depletes norepinephrine (NE) and regulates NE transporter (NET) expression. The present study examined the molecular mechanisms involved in regulation of the NET by reserpine using cultured cells. Exposure of rat PC12 cells to reserpine for a period as short as 5min decreased [(3)H]NE uptake capacity, an effect characterized by a robust decrease in the V(max) of the transport of [(3)H]NE. As expected, reserpine did not displace the binding of [(3)H]nisoxetine from the NET in membrane homogenates. The potency of reserpine for reducing [(3)H]NE uptake was dramatically lower in SK-N-SH cells that have reduced storage capacity for catecholamines. Reserpine had no effect on [(3)H]NE uptake in HEK-293 cells transfected with the rat NET (293-hNET), cells that lack catecholamine storage vesicles. NET regulation by reserpine was independent of trafficking of the NET from the cell surface. Pre-exposure of cells to inhibitors of several intracellular signaling cascades known to regulate the NET, including Ca(2+)/Ca(2+)-calmodulin dependent kinase and protein kinases A, C and G, did not affect the ability of reserpine to reduce [(3)H]NE uptake. Treatment of PC12 cells with the catecholamine depleting agent, alpha-methyl-p-tyrosine, increased [(3)H]NE uptake and eliminated the inhibitory effects of reserpine on [(3)H]NE uptake. Reserpine non-competitively inhibits NET activity through a Ca(2+)-independent process that requires catecholamine storage vesicles, revealing a novel pharmacological method to modify NET function. Further characterization of the molecular nature of reserpine's action could lead to the development of alternative therapeutic strategies for treating disorders known to be benefitted by treatment with traditional competitive NET inhibitors.

Corticosterone up-regulates expression and function of norepinephrine transporter in SK-N-BE(2)C cells

Glucocorticoids affect cellular and molecular events in brains by modulating the expression of many genes during stress. In the present study, we examined the regulatory effect of corticosterone on the expression and function of the norepinephrine transporter (NET) in vitro. The results show that exposure of SK-N-BE(2)C cells to corticosterone for 14 days significantly increased mRNA (up to 43%) and protein (up to 71%) levels of NET in the concentration-dependent manner. Longer exposure (21 days) resulted in greater increases in the levels of mRNAs (up to about 160%) and proteins (up to about 250%) of the NET. The up-regulatory effect of corticosterone on NET expression lasted a persistent period after cessation of exposure. Associated with the corticosterone-induced enhancement in NET expression, there was a parallel increase in the uptake of [(3)H]norepinephrine by SK-N-BE(2)C cells. Increased NET expression and function were abolished after exposure of cells to corticosterone in combination with mifepristone or spironolactone, two specific antagonists of corticosteroid receptors. This is consistent with the hypothesis that corticosterone-induced NET up-regulation is mediated by corticosteroid receptors. Nevertheless, there was no synergistic effect for a combination of both corticosteroid receptor antagonists. A similar up-regulation of NET protein levels was also observed after exposing PC12 cells to corticosterone. The present findings demonstrate that corticosterone up-regulates the expression and function of NET in vitro, indicating the action of corticosterone on the noradrenergic phenotype may play an important role in the correlation between stress and the development of depression.

Effects of transcription factors Phox2 on expression of norepinephrine transporter and dopamine beta-hydroxylase in SK-N-BE(2)C cells

Phox2a and Phox2b are two homeodomain proteins that control the differentiation of noradrenergic neurons during embryogenesis. In the present study, we examined the possible effect of Phox2a/2b on the in vitro expression of the norepinephrine transporter (NET) and dopamine beta-hydroxylase (DBH), two important markers of the noradrenergic system. SK-N-BE(2)C cells were transfected with cDNAs or short hairpin RNAs specific to the human Phox2a and Phox2b genes. Transfection of 0.1 to 5 mug of cDNAs of Phox2a or Phox2b significantly increased mRNA and protein levels of NET and DBH in a concentration-dependent manner. As a consequence of the enhanced expression of NET after transfection, there was a parallel increase in the uptake of [(3)H]norepinephrine. Co-transfection of Phox2a and Phox2b did not further increase the expression of noradrenergic markers when compared with transfection of either Phox2a or Phox2b alone. Transfection of shRNAs specific to Phox2a or Phox2b genes significantly reduced mRNA and protein levels of NET and DBH after shutdown of endogenous Phox2, which was accompanied by a decreased [(3)H]norepinephrine uptake. Furthermore, there was an additive effect after cotransfection with both shRNAs specific to Phox2a or Phox2b genes on NET mRNA levels. Finally, the reduced DBH expression caused by the shRNA specific to Phox2a could be reversed by transfection with Phox2b cDNA and vice versa. The present findings verify the determinant role of Phox2a and Phox2b on the expression and function of NET and DBH in vitro. Further clarifying the regulatory role of these two transcription factors on key proteins of the noradrenergic system may open a new avenue for therapeutics of aging-caused dysfunction of the noradrenergic system.

Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and arginine decarboxylase levels

Agmatine, an endogenous amine derived from decarboxylation of L-arginine catalyzed by arginine decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and arginine decarboxylase expression in rat brains. Sprague-Dawley rats were subjected to 2h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with beta-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of arginine decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and arginine decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.

Exogenous agmatine has neuroprotective effects against restraint-induced structural changes in the rat brain

Agmatine is an endogenous amine derived from decarboxylation of arginine catalysed by arginine decarboxylase. Agmatine is considered a novel neuromodulator and possesses neuroprotective properties in the central nervous system. The present study examined whether agmatine has neuroprotective effects against repeated restraint stress-induced morphological changes in rat medial prefrontal cortex and hippocampus. Sprague-Dawley rats were subjected to 6 h of restraint stress daily for 21 days. Immunohistochemical staining with beta-tubulin III showed that repeated restraint stress caused marked morphological alterations in the medial prefrontal cortex and hippocampus. Stress-induced alterations were prevented by simultaneous treatment with agmatine (50 mg/kg/day, i.p.). Interestingly, endogenous agmatine levels, as measured by high-performance liquid chromatography, in the prefrontal cortex and hippocampus as well as in the striatum and hypothalamus of repeated restraint rats were significantly reduced as compared with the controls. Reduced endogenous agmatine levels in repeated restraint animals were accompanied by a significant increase of arginine decarboxylase protein levels in the same regions. Moreover, administration of exogenous agmatine to restrained rats abolished increases of arginine decarboxylase protein levels. Taken together, these results demonstrate that exogenously administered agmatine has neuroprotective effects against repeated restraint-induced structural changes in the medial prefrontal cortex and hippocampus. These findings indicate that stress-induced reductions in endogenous agmatine levels in the rat brain may play a permissive role in neuronal pathology induced by repeated restraint stress.

Chronic treatment with glucocorticoids alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and arginine decarboxylase levels

In the present study, we examined the possible effect of chronic treatment with glucocorticoids on the morphology of the rat brain and levels of endogenous agmatine and arginine decarboxylase (ADC) protein, the enzyme essential for agmatine synthesis. Seven-day treatment with dexamethasone, at a dose (10 and 50 mug/kg/day) associated to stress effects contributed by glucocorticoids, did not result in obvious morphologic changes in the medial prefrontal cortex and hippocampus, as measured by immunocytochemical staining with beta-tubulin III. However, 21-day treatment (50 mug/kg/day) produced noticeable structural changes such as the diminution and disarrangement of dendrites and neurons in these areas. Simultaneous treatment with agmatine (50 mg/kg/day) prevented these morphological changes. Further measurement with HPLC showed that endogenous agmatine levels in the prefrontal cortex and hippocampus were significantly increased after 7-day treatments with dexamethasone in a dose-dependent manner. On the contrary, 21-day treatment with glucocorticoids robustly reduced agmatine levels in these regions. The treatment-caused biphasic alterations of endogenous agmatine levels were also seen in the striatum and hypothalamus. Interestingly, treatment with glucocorticoids resulted in a similar change of ADC protein levels in most brain areas to endogenous agmatine levels: an increase after 7-day treatment versus a reduction after 21-day treatment. These results demonstrated that agmatine has neuroprotective effects against structural alterations caused by glucocorticoids in vivo. The parallel alterations in the endogenous agmatine levels and ADC expression in the brain after treatment with glucocorticoids indicate the possible regulatory effect of these stress hormones on the synthesis and metabolism of agmatine in vivo.

Thermal desorption of hydrogen from carbon nanosheets

Carbon nanosheets are a unique nanostructure that, at their thinnest configuration, approach a single freestanding graphene sheet. Temperature desorption spectroscopy (TDS) has shown that the hydrogen adsorption and incorporation during growth of the nanosheets by radio frequency plasma-enhanced chemical vapor deposition are significant. A numerical peak fitting to the desorption spectra (300-1273 K) via the Polanyi-Wigner equation showed that desorption followed a second order process, presumably by the Langmuir-Hinshelwood mechanism. Six peaks provide the best fit to the TDS spectra. Surface desorption activation energies were determined to be 0.59, 0.63, and 0.65 eV for the external graphite surface layers and 0.85, 1.15, and 1.73 eV for desorption and diffusion from the bulk. In contrast to TDS data from previously studied a-C:H films [Schenk et al. J. Appl. Phys. 77, 2462 (1995)], a greater amount of hydrogen bound as sp(2) hybridized carbon was observed. A previous x-ray diffraction study of these films has shown a significant graphitic character with a crystallite dimension of L(a)=10.7 nm. This result is consistent with experimental results by Raman spectroscopy that show as-grown carbon nanosheets to be crystalline as commercial graphite with a crystallite size of L(a)=11 nm. Following TDS, Raman data indicate that the average crystallite increased in size to L(a)=15 nm.

Expression of arginine decarboxylase in brain regions and neuronal cells

After our initial report of a mammalian gene for arginine decarboxylase, an enzyme for the synthesis of agmatine from arginine, we have determined the regional expression of ADC in rat. We have analyzed the expression of ADC in rat brain regions by activity, protein and mRNA levels, and the regulation of expression in neuronal cells by RNA interference. In rat brain, ADC was widely expressed in major brain regions, with a substantial amount in hypothalamus, followed by cortex, and with least amounts in locus coeruleus and medulla. ADC mRNA was detected in primary astrocytes and C6 glioma cells. While no ADC message was detected in fresh neurons (3 days old), significant message appeared in differentiated neurons (3 weeks old). PC12 cells, treated with nerve growth factor, had higher ADC mRNA compared with naive cells. The siRNA mixture directed towards the N-terminal regions of ADC cDNA down-regulated the levels of mRNA and protein in cultured neurons/C6 glioma cells and these cells produced lower agmatine. Thus, this study demonstrates that ADC message is expressed in rat brain regions, that it is regulated in neuronal cells and that the down-regulation of ADC activity by specific siRNA leads to lower agmatine production.

Agmatine protects against cell damage induced by NMDA and glutamate in cultured hippocampal neurons

Agmatine is a polyamine and has been considered as a novel neurotransmitter or neuromodulator in the central nervous system. In the present study, the neuroprotective effect of agmatine against cell damage caused by N-methyl-D-aspartate (NMDA) and glutamate was investigated in cultured rat hippocampal neurons. Lactate dehydrogenase (LDH) activity assay, beta-tubulin III immunocytochemical staining and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL) assay were conducted to detect cell damage. Exposure of 12-day neuronal cultures of rat hippocampus to NMDA or glutamate for 1 h caused a concentration-dependent neurotoxicity, as indicated by the significant increase in released LDH activities. Addition of 100 microM agmatine into media ablated the neurotoxicity induced by NMDA or glutamate, an effect also produced by the specific NMDA receptor antagonist dizocilpine hydrogen maleate (MK801). Arcaine, an analog of agmatine with similar structure as agmatine, fully prevented the NMDA- or glutamate-induced neuronal damage. Spermine and putrescine, the endogenous polyamine and metabolic products of agmatine without the guanidine moiety of agmatine, failed to show this effect, indicating a structural relevance for this neuroprotection. Immunocytochemical staining and TUNEL assay confirmed the findings in the LDH measurement. That is, agmatine and MK801 markedly attenuated NMDA-induced neuronal death and significantly reduced TUNEL-positive cell numbers induced by exposure of cultured hippocampal neurons to NMDA. Taken together, these results demonstrate that agmatine can protect cultured hippocampal neurons from NMDA- or glutamate-induced excitotoxicity, through a possible blockade of the NMDA receptor channels or a potential anti-apoptotic property.

Age-associated changes in mRNA levels of Phox2, norepinephrine transporter and dopamine beta-hydroxylase in the locus coeruleus and adrenal glands of rats

Age-related changes in the gene expression of the transcription factors, Phox2a and 2b, and two marker proteins, norepinephrine transporter (NET) and dopamine beta-hydroxylase (DBH), of noradrenergic neurons were characterized in the locus coeruleus (LC) and adrenal glands using in situ hybridization. Analysis of changes was performed in rats that were 1-23 months of age. Compared to 1-month-old rats, there was a 62% increase of Phox2a messenger RNA (mRNA) in the LC of 3-month-old rats, and a decline of 37% in 23-month-old rats. In contrast, levels of Phox2b mRNA in the LC remained unchanged in 3-month-old rats, but declined to a 30% reduction in 23-month-old rats. Interestingly, mRNA levels of NET in the LC decreased with increasing age to a reduction of 29%, 30% and 43% in 3-, 8- and 23-month-old rats, respectively. Similarly, DBH mRNA in the LC declined with increasing age to a 56% reduction in 23-month-old rats. mRNA levels of Phox2a, Phox2b, NET and DBH in the adrenal medulla of 23-month-old rats were significantly lower than those of 1-month-old rats. Semi-quantitative reverse transcription assays of the same genes yielded data similar to in situ hybridization experiments, with beta-actin mRNA levels being unchanged across the ages. Taken together, these data reveal that reduced Phox2 mRNAs in the LC and adrenal medulla of aging rats are accompanied by a coincidental decline in mRNA levels of NET and DBH and suggest a possible relationship between Phox2 genes and the marker genes in noradrenergic neurons after birth.

Norepinephrine transporter function and desipramine: residual drug effects versus short-term regulation

Previous research has shown that exposure of norepinephrine transporter (NET)-expressing cells to desipramine (DMI) downregulates the norepinephrine transporter, although changes in the several transporter parameters do not demonstrate the same time course. Exposures to desipramine for <1 day reduces only radioligand binding and uptake capacity while transporter-immunoreactivity is unaffected. Recent demonstration of persistent drug retention in cells following desipramine exposures raises the possibility that previous reported changes in the norepinephrine transporter may be partly accountable by residual drug. In this study, potential effects of residual desipramine on norepinephrine transporter binding and uptake were re-evaluated following exposures of PC12 cells to desipramine using different methods to remove residual drug. Using a method that minimizes residual drug, exposure of intact PC12 cells to desipramine for 4h had no effect on uptake capacity or [(3)H]nisoxetine binding to the norepinephrine transporter, while exposures for > or =16 h reduced uptake capacity. Desipramine-induced reductions in binding to the transporter required >24 h or greater periods of desipramine exposure. This study confirms that uptake capacity of the norepinephrine transporter is reduced earlier than changes in radioligand binding, but with a different time course than originally shown. Special pre-incubation procedures are required to abolish effects of residual transporter inhibitor when studying inhibitor-induced transporter regulation.

Effects of desipramine treatment on tyrosine hydroxylase gene expression in cultured neuroblastoma cells and rat brain tissue

Activity and expression of tyrosine hydroxylase (TH), the rate-limiting enzyme for catecholamine synthesis, are modified in response to antidepressant-treatment. We examined effects of the selective norepinephrine-transporter (NET) inhibitor antidepressant desipramine (DMI) on expression of TH in human neuroblastoma cells (SK-N-BE[2]M17) and in rat brain regions. TH mRNA levels were determined by Northern blot in vitro, and by in situ hybridization ex vivo; TH protein levels were measured by western blot. Brief exposure of neuroblastoma cells to 0 vs. 5, 50, or 500 nM of DMI had little effect on TH mRNA levels, but exposure to 50 and 500 nM DMI for 14 days increased the mRNA by up to 72%, with a continuous rise from 3 to 14 days of exposure to 500 nM DMI. In contrast, 500 nM DMI led to an initial slight increase, followed by a continuous and sustained decrease in TH protein level by up to 53%, from day 3 to day 14. Daily treatment of rats with DMI (10 mg/kg, i.p.) for 3 or 14 days significantly increased postmortem cerebral TH mRNA in the locus coeruleus (LC) area by 47-68%. Again, TH protein concentrations in LC decreased at 3 and 14 days, by 25-40%, with transient significant reduction in amygdala tissue after 3 days of treatment that were not sustained. These findings indicate that DMI exerts complex, typically opposite and perhaps compensatory, gradually evolving effects on the expression of TH protein (decreases) and its message (increases), possibly in response to increased synaptic availability of NE.

Direct evidence for predation on trilobites in the Cambrian

A fossil arthropod similar to Fuxianhuia and displaying an exceptionally well-preserved alimentary canal with in situ gut contents is reported from the lower Middle Cambrian (ca. 510 Myr ago) of South China. Three-dimensionally preserved, paired phosphatic nodules, arranged in series along both sides of the gut and containing spherical bacteria, probably represent serial digestive glands. The gut is filled with fragments of the eodiscoid trilobite, Pagetia. The well-developed digestive glands and the fragmentary trilobite remains suggest (i) that the arthropod was a durophagous, possibly selective predator, and (ii) that small trilobites such as eodiscoids were a major food source in Cambrian marine ecosystems. This fossil association augments the small number of previously described associations providing more or less direct evidence of predator-prey relationships in Cambrian epibenthic communities.

Effect of agmatine against cell death induced by NMDA and glutamate in neurons and PC12 cells

AIMS

Agmatine is an endogenous guanido amine and has been shown to be neuroprotective in vitro and in vivo. The aims of this study are to investigate whether agmatine is protective against cell death induced by different agents in cultured neurons and PC12 cells.

METHODS

Cell death in neurons, cultured from neonatal rat cortex, was induced by incubating with (a) NMDA (100 microM) for 10 min, (b) staurosporine (protein kinase inhibitor, 100 nM) for 24 h, and (c) calcimycin (calcium ionophore, 100 nM) for 24 h in the presence and absence of agmatine (1 micro M to 1 mM). Cell death in PC12 cells was induced by exposure to glutamate (10 mM), staurosporine (100 nM), and calcimycin (100 nM). The activity of lactate dehydrogenase (LDH) in the medium was measured as the marker of cell death and normalized to cellular LDH activity.

RESULTS

Agmatine significantly reduced the medium LDH in NMDA-treated neurons but failed to reduce the release of LDH induced by staurosporin or calcimycin. In PC12 cells, agmatine significantly reduced LDH release induced by glutamate exposure, but not by staurosporine or calcimycin. Agmatine itself neither increased LDH release nor directly inhibited the enzyme activity.

CONCLUSION

We conclude that agmatine protects against NMDA excitotoxicity in neurons and PC12 cells but not the cell death induced by protein kinase blockade or increase in cellular calcium.

The persistent membrane retention of desipramine causes lasting inhibition of norepinephrine transporter function

The present study examined the potential membrane retention of desipramine (DMI) following exposures of 293-hNET cells to DMI, and its effect on [3H]NE uptake. Incubation of cells with 500 nM DMI for 1 h or 1 day persistently inhibited the uptake of [3H]NE up to 7 days, despite daily repeated washing of cells with drug-free medium. Uptake inhibition was paralleled by persistent retention of DMI associated with cells, as determined by HPLC and by radiotracer experiments using [3H]DMI. [3H]DMI trapped in membranes was displaceable by the structurally unrelated NET inhibitor, nisoxetine, in a concentration-dependent manner, implying interaction of retained [3H]DMI with the NET. A similar cellular retention was observed following incubation of cells with nisoxetine. The results demonstrate that DMI and nisoxetine are persistently retained in cell membranes, at least partly in association with the NET. The retention and slow diffusion of DMI and nisoxetine from membranes may contribute to their pharmacological and modulatory action on NET.

Expression of human arginine decarboxylase, the biosynthetic enzyme for agmatine

Agmatine, an amine formed by decarboxylation of L-arginine by arginine decarboxylase (ADC), has been recently discovered in mammalian brain and other tissues. While the cloning and sequencing of ADC from plant and bacteria have been reported extensively, the structure of mammalian enzyme is not known. Using homology screening approach, we have identified a human cDNA clone that exhibits ADC activity when expressed in COS-7 cells. The cDNA and deduced amino acid sequence of this human ADC clone is distinct from ADC of other forms. Human ADC is a 460-amino acid protein that shows about 48% identity to mammalian ornithine decarboxylase (ODC) but has no ODC activity. While naive COS-7 cells do not make agmatine, these cells are able to produce agmatine, as measured by HPLC, when transfected with ADC cDNA. Northern blot analysis using the cDNA probe indicated the expression of ADC message in selective human brain regions and other human tissues.

Effects of desipramine treatment on norepinephrine transporter gene expression in the cultured SK-N-BE(2)M17 cells and rat brain tissue

The antidepressant desipramine (DMI) is a selective inhibitor of norepinephrine (NE) transport that down-regulates the norepinephrine transporter (NET) protein in a concentration- and time-dependent manner in vitro. In this study, possible regulatory effects of DMI on NET mRNA and protein levels were investigated with the NET-expressing SK-N-BE(2)M17 cell line and rat brain tissue. Northern blot analysis showed that incubation of the cultured cells with DMI (5-500 nm) for 3 days reduced levels of NET mRNA in both its 5.8-kb (by up to 58%) and 3.6-kb forms (to 68%), whereas incubation for 14 days increased both levels (to 40% and 100%) in a concentration-dependent manner. In contrast, NET protein levels decreased after 3-14 days of exposure of the cells to DMI, as determined by western blotting. The in vitro findings were supported by in vivo treatment of rats with DMI. Thus, in situ hybridization demonstrated initially decreased, and later increased, NET mRNA levels in locus coeruleus (LC) tissue of rats treated with DMI; whereas NET protein levels in the LC were reduced after 14 days, but unchanged after three daily DMI treatments. Thus, DMI had similar effects on NET expression in vitro and in vivo, with opposite changes in NET mRNA and protein levels, suggesting that the regulatory mechanisms involved are complex and non-congruent.