Functional magnetic nanoparticle assemblies: formation, collective behavior, and future directions

This Perspective describes recent progress in the development of functional magnetic nanoparticle assemblies. After describing the formation of two- and three-dimensional particle arrays in terms of the size-dependent driving forces, we focus on magnetic nanoparticle arrays. We discuss how the self-organized structure can modify the magnetic behavior, relative to that of isolated particles. We highlight an important development, described in this issue of ACS Nano by Kostiainen and co-workers, who have demonstrated not only the novel aqueous self-assembly of magnetic particles but also controlled and reversible disassembly. Finally, we explore two inter-related future directions for self-assembly of magnetic nanoparticles: the formation of more complex, hierarchical structures and the integration of self-assembly with fabrication techniques for electronic devices.

Generation of dopaminergic neurons by fusion of neural stem cells and midbrain neurons

Neural stem cells (NSCs) are multipotent and self-renewing that can potentially generate various neurons for clinical purposes. However, the mechanism of regulating differentiation from NSCs to neurons is not well understood. In this report, we established a new method to obtain specific neurons from NSCs by cell fusion. NSCs were fused with midbrain neurons, resulting in hybrid cells that express an antigen pattern characteristic of dopaminergic neurons. Analysis of the marker enzyme tyrosine hydroxylase (TH) showed that hybrid cells were reprogrammed to somatic cells. This report represents a new significant contribution toward revealing the directional differentiation of NSCs and eventually providing the application in clinical transplantation therapy.

CASCADE_SCAN: mining signal transduction network from high-throughput data based on steepest descent method

BACKGROUND

Signal transduction is an essential biological process involved in cell response to environment changes, by which extracellular signaling initiates intracellular signaling. Many computational methods have been generated in mining signal transduction networks with the increasing of high-throughput genomic and proteomic data. However, more effective means are still needed to understand the complex mechanisms of signaling pathways.

RESULTS

We propose a new approach, namely CASCADE_SCAN, for mining signal transduction networks from high-throughput data based on the steepest descent method using indirect protein-protein interactions (PPIs). This method is useful for actual biological application since the given proteins utilized are no longer confined to membrane receptors or transcription factors as in existing methods. The precision and recall values of CASCADE_SCAN are comparable with those of other existing methods. Moreover, functional enrichment analysis of the network components supported the reliability of the results.

CONCLUSIONS

CASCADE_SCAN is a more suitable method than existing methods for detecting underlying signaling pathways where the membrane receptors or transcription factors are unknown, providing significant insight into the mechanism of cellular signaling in growth, development and cancer. A new tool based on this method is freely available at http://www.genomescience.com.cn/CASCADE_SCAN/.

Matrix metalloproteinase levels in acute aortic dissection, acute pancreatitis and other abdominal pain

BACKGROUND

Acute aortic dissection (AAD) is a life-threatening emergency. Patients with AAD who have abdominal pain are easily confused with patients with surgical acute abdomen. Matrix metalloproteinases (MMPs) play an important role in the pathophysiology of AAD. This study was undertaken to compare serum MMP-9 levels in patients with acute abdomen and those with AAD presenting as abdominal pain in the emergency department.

METHODS

Blood samples were collected within 1 h and 24 h after admission to the emergency department. Serum levels of MMP-9, lipoprotein (a) (LP(a)) and high-sensitivity C-reactive protein (hsCRP) were measured in 20 healthy controls, 20 patients with acute pancreatitis, 20 with other acute abdomen and 20 patients with AAD with abdominal pain by enzyme-linked immunosorbent assay and immunoturbidimetric assay, respectively.

RESULTS

Serum MMP-9, LP(a) and hsCRP levels were significantly higher in the three groups of patients than in the healthy controls, with no significant fluctuation within 24 h of admission in any group. Mean serum MMP-9 levels in patients with acute pancreatitis (768 (95% CI 651 to 885) ng/ml within 1 h; 708 (95% CI 677 to 740) ng/ml at 24 h) were significantly higher than in patients with other acute abdomen (244 (95% CI 182 to 266) ng/ml within 1 h; 259 (95% CI 219 to 299) ng/ml at 24 h) and lower than in patients with AAD (1052 (95% CI 921 to 1183) ng/ml at 1 h; 1107 (95% CI 973 to 1241) ng/ml at 24 h) (all p<0.05). No significant difference was detected in serum LP(a) and hsCRP levels among the three groups of patients.

CONCLUSIONS

Patients with AAD who have abdominal pain have significantly higher serum MMP-9 levels than patients with surgical acute abdomen.

Quality of life and psychologic distress of recipients after adult living-donor liver transplantation (LDLT)-A study from mainland China

This cross-sectional study investigated potential factors impacting quality of life in 125 recipients after living-donor liver transplantation (LDLT). Health-related quality of life (HRQoL) was measured by using the Chinese version of Medical Outcomes Study Short Form-36 (SF-36), and psychologic symptoms by using the Symptom Checklist-90-Revised (SCL-90-R). Clinical and demographic data were collected from the records of the Chinese Liver Transplant Registry and via questionnaire. A total of 102 recipients (81.6%) completed the questionnaires. All SF-36 domain scores (except the mental health score) were lower in the study than in the general population of Sichuan. The mental quality of life was significantly lower in female than in male subjects (P = .000). Regarding the role-physical (P = .016), social functioning (P = .000), and role-emotional (P = .004) domains, recipients >1 year after transplantation scored higher than those <1 year. Bodily pain scores were lower in recipients with prior acute liver failure than those with hepatic carcinoma or hepatic cirrhosis (P = .032). Social functioning was poorer in recipients with than in those without complications (P = .039). Mental component summary scale (MCS) scores and some of physical component summary scale (PCS) significantly correlated with symptom dimension scores of the SCL-90-R (P < .05). In conclusion, gender, time since transplant, etiology of disease, complications, occupation, and some psychologic symptoms were possible factors influencing postoperative HRQoL of LDLT recipients.

Silencing of Rho-GDIgamma by RNAi promotes the differentiation of neural stem cells

RNA interference (RNAi) technology is one of the main means in the study of stem cell differentiation. This study describes Rho-GDIgamma function during the differentiation of neural stem cells by using RNAi. Rho-GDIgamma belongs to the Rho-GDI protein family, which is expressed at high level throughout the brain. Although it exists in neuronal population, its physiological function is poorly understood. By using RNAi technology to downregulate expression of Rho-GDIgamma, we found distinct morphological changes in neural stem cell line C17.2. More important, RT-PCR confirmed that RNAi-mediated downregulation of Rho-GDIgamma decreased expression of Rho-GDIgamma-regulated genes RhoA and slightly increased expression of Rac1. Further, immunochemical staining indicated that downregulation of Rho-GDIgamma increased the tendency of C17.2 cells to differentiate. These data strongly suggest that Rho-GDIgamma plays a key role in the differentiation of neural stem cells.

Internalization, translocation and biotransformation of silica-coated titanium dioxide nanoparticles in neural stem cells

Nanotechnology has gained massive applications in the fields of biology and pharmacology. Recently, more research attention has been paid to explore the interaction between nanoparticles (NPs) and cells, in particular, the entry of NPs into cells. Herein, we focus on the internalization of the FITC-labeled silica-coated titania NPs (FITC-TiO2@SiO2 NPs) in neural stem cells (NSCs) and their subsequent translocation. Various microscopic techniques, such as confocal-laser-scanning microscopy (CFLSM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to track the time-dependent pathway of NPs in cells. It was found that NPs traversed cell membrane and localized around the cell nucleus. Most NPs congregated in lysosomes and were transformed by lysosomes after 48 h co-incubation.

Prophylaxis against hepatitis B recurrence posttransplantation using lamivudine and individualized low-dose hepatitis B immunoglobulin

Although the combination of lamivudine (LAM) and high-dose intravenous (IV) hepatitis B immunoglobulin (HBIG) is very effective in preventing hepatitis B virus (HBV) recurrence after liver transplantation (LT), the major limitation of this regimen is its high cost. A more cost-effective, convenient and widely accepted regimen is urgently needed. We evaluated the safety and efficacy of another strategy using LAM and individualized low-dose intramuscular (IM) HBIG. Between May 2002 and December 2009, a total of 254 adult patients undergoing LT for HBV-related benign end-stage liver diseases received this regimen in our center. The mean follow-up of these patients was 41.2 +/- 22.7 months. Their 1-, 3- and 5-year survival rates were 85.3%, 77.4% and 76.4%, respectively, and 1-, 3- and 5-year HBV recurrence rates were 2.3%, 6.2% and 8.2%. Fourteen patients experienced posttransplant HBV recurrence. Pretransplant high viral load and posttransplant prednisone withdrawal time were observed to be associated with recurrence. In conclusion, combination therapy with LAM and individualized low-dose IM HBIG provides a safe and effective prophylaxis against HBV recurrence after LT at about 5% of the cost of conventional high-dose IV HBIG regimens.

A protein interaction network for the analysis of the neuronal differentiation of neural stem cells in response to titanium dioxide nanoparticles

The effects of titanium dioxide (TiO(2)) nanoparticles (NPs) on the differentiation of neural stem cells are reported. Our findings indicate that TiO(2) NPs lead to a differentiational tendency towards neurons from neural stem cells, suggesting TiO(2) NPs might be a beneficial inducer for neuronal differentiation. To insight into the possible molecular mechanism of the neuronal differentiation, we conducted a protein-protein interaction network (PIN) analysis. To this end, a global mapping of target proteins induced by TiO(2) NPs was first made by a 2-dimensional electrophoresis analysis. Results showed that 9 proteins were significantly changed and then they were subjected to the mass spectrometric assay. All 9 identified proteins are involved in signal, molecular chaperones, cytoskeleton, and nucleoprotein. Further, based on our experimental data and DIP, IntAct-EBI, GRID database, a protein-protein interaction network was constructed, which provides highly integrated information exhibiting the protein-protein interaction. By analysis of the gene expression, the signal pathway involving Cx43 phosphorylation, which is negatively regulated by the protein kinase C epsilon (PKCepsilon), is demonstrated. It is inferred that PKCepsilon plays a pivotal negative role in the neuronal differentiation of stem neural cells in response to the TiO(2) NPs exposure.

Ammonium removal from aqueous solutions by zeolite adsorption together with chemical precipitation

The aim of this study was to remove ammonium from aqueous solution and recycle ammonium. Ammonium removal from aqueous solution by natural and pretreated zeolites, breakthrough curve, chemical regeneration of pretreated zeolite, ammonium removal from regeneration solution by chemical precipitation and NH(4) (+) adsorption isotherms were investigated by conducting a series of batch and continuous experiments in this study. Morphologies and structures of zeolites were analyzed by Surface Area and Pore Size analysis, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The NH(4) (+)-N removal efficiencies by natural and NaCl-treated zeolite were 30.73% and 85.55% respectively at an initial concentration of 100 mg/L. Breakthrough and exhaustion capacities for adsorption of ammonium ions were 3.36 and 4.26 mg /g (NH(4) (+)-N/zeolite), respectively. After chemical regeneration, NH(4) (+)-N removal efficiency by NaCl-treated zeolite only reduced 9.95% than previously. NH(4) (+)-N concentration of the regeneration solution was reduced from 460 to 74.55 mg/L by chemical precipitation. The Freundlich isotherm provided a slightly more consistent fit to the experimental data of ammonium adsorption on NaCl-treated zeolite than Langmuir. Based on the results, it was concluded that the objective of this study had been well achieved.

Diabetes mellitus after living donor liver transplantation: data from mainland China

Most reported data on posttransplantation diabetes mellitus (PTDM) are from Western countries with patients who underwent deceased donor liver transplantation. A retrospective study was performed to assess the prevalence and predictive factors of PTDM in the context of living donor liver transplantation (LDLT) in the Chinese population using the definition of PTDM proposed in 2003 by the World Health Organization and the American Diabetes Association. The prevalence of DM after LDLT in our study was 25% (21/84), and the incidence of PTDM was 14.9% (11/74) with 64% of cases diagnosed within 3 months after LDLT; 9.5% were observed to show impaired fasting glucose postoperatively. Multivariate analysis identified body mass index >or= 25 kg/m(2) before LDLT as the only independent risk factor for developing PTDM. Only one patient was operated for hepatitis C virus (HCV) infection. Hepatitis B virus (HBV)-related diseases were common in our study population, accounting for 78.6% of all patients. Both HCV and HBV infection status were not independent risk factors for developing PTDM. In addition, a greater tacrolimus trough blood level in the PTDM group versus no-DM group was observed at 3 months post-LDLT (11.03 ng/mL vs 4.87 ng/mL). The mean tacrolimus dose was not significantly different between the two groups. In conclusion, PTDM was prevalent among Chinese LDLT recipients.

[Safety analysis of dust mite allergen for diagnosis and immunotherapy of asthma and rhinitis]

AIM

To make a retrieval investigation of safety in using Dermatophagoides farinae extract in diagnosis and immunotherapy with patients of asthma and rhinitis.

METHODS

A questionnaire evaluation of the safety use of D. farinae extract (SMU-Df) during diagnosis and immunotherapy of patients from 1974 to 1995 was carried out.

RESULTS

A total of 8,46,342 injections were statistically analysed, among whom 142 systemic adverse reactions occurred involving urticaria 0.82@10000, severe attack of asthma 0.77@10000, anaphylactic shock 0.07@10000 (CL = 1.4-12.0/million), and angioedma 0.02@10000. The time of onset of systemic reactions of immediate type was < 30 min in 32 cases-times, and 1 h and 2 h in 6 cases-times; the time to onset of late response type was 3 h-48 h in 23 cases-times with highest incidence of severe asthmatic attacks. The systemic reactions occurred in 18 subjects during skin test, in 96 cases-times during increasing dose phase, and in 14 cases-times during. Among them 6 cases were of anaphylactic shock, and none of it after emergency treatment. The major cause of manifestation of systemic reactions for 41 cases after immunotherapy with SMU-Df extract was due to over dosage errors.

CONCLUSION

The application of SMU-Df extract in skin test and immunotherapy of asthma and rhinitis sensitive to mite for the past 22 years in this country indicated that the efficacy and safety have been high.

Following-up of a four-dose daclizumab induction therapy without calcineurin inhibitors in a liver transplantation recipient with severe renal dysfunction: a case report

BACKGROUND

There is debate on the dose schedule and pharmacokinetics of daclizumab in liver transplant recipients.

METHODS

A four-dose course of daclizumab was administered to a patient with severe renal dysfunction. Calcineurin inhibitor therapy initiation was delayed to 86 days posttransplantation.

RESULTS

The patient is well as 480 days after transplantation. No rejection was observed.

CONCLUSIONS

The result suggested the efficacy of our dose schedule, but it will be necessary to confirm it with further pharmacokinetic studies and more cases.

Protective effects of pirfenidone on D-galactosamine and lipopolysaccharide-induced acute hepatotoxicity in rats

OBJECTIVE AND DESIGN

To investigate the protective effects of pirfenidone on acute liver damage caused by D-galactosamine (GalN)/lipopolysaccharide (LPS) in rats.

MATERIAL AND TREATMENT

Sprague-Dawley rats were divided into five groups (five rats per group): normal control group, GalN/LPS-treated group, and three pirfenidone-treated group (100, 300 and 500 mg/kg i.p., respectively). All biochemical and histological indexes were determined at 12 h after GalN/LPS challenge.

METHODS

Severity of liver injury was assessed by determination of serum ALT, AST levels and histological analysis. SOD activity and MDA concentrations as well as TNF-alpha and IFN-gamma levels in the liver of rats were measured. The expression of iNOS and its product, NO concentration were also determined.

RESULTS

Pretreatment with pirfenidone significantly attenuated GalN/LPS-induced severe hepatotoxicity, as evidenced by decreased ALT, AST levels and MDA content and improved histopathological changes. Pirfenidone inhibited the elevated levels of TNF-alpha and IFN-gamma and reduced the induction of iNOS/NO in a dose-dependent manner, which might be important mechanisms related to its protective effect.

CONCLUSIONS

Pirfenidone can provide a definite protective effect against acute hepatic injury caused by GalN/LPS in rats, which may be mainly mediated through its anti-inflammatory effect.

Modeling of Nociceptor Transduction in Skin Thermal Pain Sensation

All biological bodies live in a thermal environment with the human body as no exception, where skin is the interface with protecting function. When the temperature moves out of normal physiological range, skin fails to protect and pain sensation is evocated. Skin thermal pain is one of the most common problems for humans in everyday life as well as in thermal therapeutic treatments. Nocicetors (special receptor for pain) in skin play an important role in this process, converting the energy from external noxious thermal stimulus into electrical energy via nerve impulses. However, the underlying mechanisms of nociceptors are poorly understood and there have been limited efforts to model the transduction process. In this paper, a model of nociceptor transduction in skin thermal pain is developed in order to build direct relationship between stimuli and neural response, which incorporates a skin thermomechanical model for the calculation of temperature, damage and thermal stress at the location of nociceptor and a revised Hodgkin–Huxley form model for frequency modulation. The model qualitatively reproduces measured relationship between spike rate and temperature. With the addition of chemical and mechanical components, the model can reproduce the continuing perception of pain after temperature has returned to normal. The model can also predict differences in nociceptor activity as a function of nociceptor depth in skin tissue.

A novel function of dcf1 during the differentiation of neural stem cells in vitro

The study of neural dendrite formation is of great significance both in theory and applications. However, the molecular mechanisms of regulation remain unclear. We previously described a novel EST, which has high homology with dentritic cell factors (DCF1), expressed differentially between undifferentiated and differentiated neural stem cells (NSCs). In this study, we cloned, expressed, and silenced the dcf1 gene and offered insight into its function in regulating dendrite formation during the differentiation of NSCs. The results indicated that dcf1 encoded a 42 kD protein and could be successfully expressed both in Escherichia coli and NSCs. In order to silence dcf1 gene, three different kinds of siRNA vectors were constructed and transformed into the NSC line C17.2 and primary NSCs, resulting in down regulation of the dcf1 mRNA. Analysis of immunofluorescence or GFP illuminated that with overexpression of the dcf1 gene, the NSCs were maintained in undifferentiated status. After the dcf1 gene was silenced, cells tended to differentiate into neurons and astrocytes.