激光剥离制作无机纳米粒子

纳米粒子具有高的表面积，呈现更佳的物理与化学特性，常用于塑橡胶的添加物来改善或增进应用的特性，有许多纳米粒子的制作方法已商用化，激光剥离方式以脉冲能量自物体表面产生纳米粒子，为制作各种纳米粒子尤其组成或晶相复杂的纳米粒子的重要方法。随使用靶材的微结构与晶相，可经由剥离条件的调整获得多晶相的纳米粒子，粒径在50纳米以下同时呈现圆形的外观，纳米粒子的组成由靶材组成，反应性气体与激光能量决定。使用如氧化钛光触媒之还原效果，进一步在纳米粒子表面披覆银粒子，具有核壳结构的纳米粒子具有更多的特性，有更大的应用潜力。     

Targeted polymeric micelles for delivery of poorly soluble drugs

Polymeric micelles (micelles formed by amphiphilic block copolymers) demonstrate a series of attractive properties as drug carriers, such as high stability both in vitro and in vivo and good biocompatibility, and can be successfully used for the solubilization of various poorly soluble pharmaceuticals. These micelles can also be used as targeted drug delivery systems. The targeting can be achieved via the enhanced permeability and retention effect (into the areas with the compromised vasculature), by making micelles of stimuli-responsive amphiphilic block copolymers, or by attaching specific targeting ligand molecules to the micelle surface. Immunomicelles prepared by coupling monoclonal antibody molecules to p-nitrophenylcarbonyl groups on the water-exposed termini of the micelle corona-forming blocks demonstrate high binding specificity and targetability. Immunomicelles prepared with cancer-specific monoclonal antibody 2C5 specifically bind to different cancer cells in vitro and demonstrate increased therapeutic activity in vivo. This new family of pharmaceutical carriers can be used for the solubilization and targeted delivery of poorly soluble drugs to various pathological sites in the body.     

Colloidal drug carriers: achievements and perspectives

Colloidal drug carriers such as liposomes and nanoparticles are able to modify the distribution of an associated substance. They can therefore be used to improve the therapeutic index of drugs by increasing their efficacy and/or reducing their toxicity. If these delivery systems are carefully designed with respect to the target and route of administration, they may provide one solution to some of the delivery problems posed by new classes of active molecules such as peptides, proteins, genes, and oligonucleotides. They may also extend the therapeutic potential of established drugs such as doxorubicin and amphotericin B. This article discusses the use of colloidal, particulate carrier systems (25 nm to 1 μm in diameter) in such applications. In particular, systems which show diminished uptake by mononuclear phagocytes are described. Specific targeting of carriers to particular tissues or cells is also considered. Received 8 April 2002; received after revision 25 June 2002; accepted 26 June 2002     

Cationic host defence peptides: Innate immune regulatory peptides as a novel approach for treating infections

An increase in antibiotic resistance and the emergence of new pathogens has led to an urgent need for alternative approaches to infection management. Immunomodulatory molecules that do not target the pathogen directly, but rather selectively enhance and/or alter host defence mechanisms, are attractive candidates for therapeutic development. Natural cationic host defence peptides represent lead molecules that boost innate immune responses and selectively modulate pathogen-induced inflammatory responses. This review discusses recent evidence exploring the mechanisms of cationic host defence peptides as innate immune regulators, their role in the interface of innate and adaptive immunity, and their potential application as beneficial therapeutics in overcoming infectious diseases. Received 3 November 2006; received after revision 14 December 2006; accepted 22 January 2007     

Adaptation to antiangiogenic therapy in neurological tumors

Because tumors require a vascular supply for their survival and growth, angiogenesis is considered an important therapeutic target in most human cancers including cancer of the central nervous system. Antiangiogenic therapy has focused on inhibitors of the vascular endothelial growth factor (VEGF) signaling pathway. VEGF pathway-targeted drugs have shown therapeutic efficacy in several CNS tumors and have been tried most frequently in glioblastoma. These therapies, however, have been less effective than anticipated as some patients do not respond to therapy and some receive only modest benefit. Underlying this suboptimal response are multiple mechanisms of drug resistance involving changes in both tumor cells and their microenvironment. In this review, we discuss the multiple proposed mechanisms by which neurological tumors evolve to become resistant to antiangiogenic therapies. A better understanding of these mechanisms, their context, and their interplay will likely facilitate improvements in pharmacological strategies for the targeted treatment of neurological tumors.     

The clinical potential of sphingolipid-based therapeutics

The era of sphingolipid-based therapeutics is upon us. A large body of work has been accumulating that demonstrates the distinct biological roles of sphingolipids in maintaining a homeostatic environment and in responding to environmental stimuli to regulate cellular processes. It is thus necessary to further investigate alterations in sphingolipid-metabolism in pathological conditions and, in turn, try to exploit altered sphingolipid-metabolizing enzymes and their metabolites as therapeutic targets. This review will examine how advances in the fields of drug delivery, drug discovery, synthetic chemistry, enzyme replacement therapy, immunobiology, infectious disease and nanotechnology have delivered the potential and promise of utilizing and/or targeting sphingolipid metabolites as therapies for diverse diseases.     

Therapeutic Protein Kinase Inhibitors

Protein kinase inhibitors represent an important and still emerging class of targeted therapeutic agents. Drug discovery and development strategies have explored numerous approaches to target the inhibition of protein kinase signaling. This review will highlight some of the strategies that have led to the successful clinical development of therapeutic protein kinase inhibitors, particularly as anticancer drugs. Some notable advances have been made in the development of novel protein and oligonucleotide-based biologics that target growth factor or receptor tyrosine kinases. Also, advances have been made in the rational design of small-molecule inhibitors that target unique kinase conformational forms and binding sites, and have specific kinase selectivity profiles. A review will also be given of some of the potential clinical toxicities and adverse side-effects associated with these kinase-targeted drugs. Therapeutic protein kinase inhibitors have been highly beneficial to cancer patients and offer the promise of future therapies for other diseases as well. Received 02 September 2008; received after revision 13 October 2008; accepted 15 October 2008     

Single-chain polymer nanoparticles

The synthesis of polymer nanoparticles (NPs) with controlled characteristics has become an appealing research topic lately. Nanomedicine, and especially drug delivery and imaging, are fields that require particles of a controlled size and with a tailored arrangement of functional groups. Intramolecular cross-linking or collapse of single polymer chains has emerged as an efficient alternative for the synthesis of well-defined polymer NPs. This technique allows the generation of 1.5–20 nm particles with a wide variety of chemical compositions and functionalities. This review begins by gathering synthetic strategies described in the literature and groups them into four main synthetic methods: homo-functional collapse, hetero-functional collapse, crosslinker-mediated collapse, and one-block collapse of diblock or triblock copolymers. Afterwards, the main characterization techniques and physical properties of single-chain polymer NPs (SCPNs) are exposed. Finally, several applications in nanomedicine are mentioned followed by some future perspectives.     

Intracellular localization of DR5 and related regulatory pathways as a mechanism of resistance to TRAIL in cancer

TNF-related apoptosis-inducing ligand (TRAIL) is a prominent cytokine capable of inducing apoptosis. It can bind to five different cognate receptors, through which diverse intracellular pathways can be activated. TRAIL’s ability to preferentially kill transformed cells makes it a promising potential weapon for targeted tumor therapy. However, recognition of several resistance mechanisms to TRAIL-induced apoptosis has indicated that a thorough understanding of the details of TRAIL biology is still essential before this weapon can be confidently unleashed. Critical to this aim is revealing the functions and regulation mechanisms of TRAIL’s potent death receptor DR5. Although expression and signaling mechanisms of DR5 have been extensively studied, other aspects, such as its subcellular localization, non-signaling functions, and regulation of its membrane transport, have only recently attracted attention. Here, we discuss different aspects of TRAIL/DR5 biology, with a particular emphasis on the factors that seem to influence the cell surface expression pattern of DR5, along with factors that lead to its nuclear localization. Disturbance of this balance apparently affects the sensitivity of cancer cells to TRAIL-mediated apoptosis, thus constituting an eligible target for potential new therapeutic agents.     

Custom-designed zinc finger nucleases: What is next?

Custom-designed zinc finger nucleases (ZFNs)--proteins designed to cut at specific DNA sequences--combine the non-specific cleavage domain (N) of Fok I restriction endonuclease with zinc finger proteins (ZFPs). Because the recognition specificities of the ZFPs can be easily manipulated experimentally, ZFNs offer a general way to deliver a targeted site-specific double-strand break (DSB) to the genome. They have become powerful tools for enhancing gene targeting--the process of replacing a gene within a genome of cells via homologous recombination (HR)--by several orders of magnitude. ZFN-mediated gene targeting thus confers molecular biologists with the ability to site-specifically and permanently alter not only plant and mammalian genomes but also many other organisms by stimulating HR via a targeted genomic DSB. Site-specific engineering of the plant and mammalian genome in cells so far has been hindered by the low frequency of HR. In ZFN-mediated gene targeting, this is circumvented by using designer ZFNs to cut at the desired chromosomal locus inside the cells. The DNA break is then patched up using the new investigator-provided genetic information and the cells' own repair machinery. The accuracy and high efficiency of the HR process combined with the ability to design ZFNs that target most DNA sequences (if not all) makes ZFN technology not only a powerful research tool for site-specific manipulation of the plant and mammalian genomes, but also potentially for human therapeutics in the future, in particular for targeted engineering of the human genome of clinically transplantable stem cells.     

Sialyl Lewisx-liposomes as vehicles for site-directed, E-selectin-mediated drug transfer into activated endothelial cells

E-selectin, exclusively expressed on activated endothelial cells, is a potential target for site-directed delivery of agents. We and others have shown that sialyl Lewis^x-liposomes (sLe^x-liposomes) are recognized by E-selectin. We now report an approach employing sLe^x-liposomes to deliver antisense oligonucleotides (AS-ODNs) directed against the adhesion molecule ICAM-1 to activated vascular endothelial cells. ICAM-1 expression was analyzed at the protein level by immunofluorescence and a cell surface ELISA, and at the RNA level by RT-PCR. We have investigated two different AS-ODNs complementary to the 3′ untranslated region and the AUG translation initiation codon of ICAM-1 mRNA. Both inhibited protein expression, but did not influence the mRNA level, pointing to a hybridization of AS-ODNs with the mRNA in the cytoplasm. Our results demonstrate the feasibility of a novel approach for the delivery of agents to activated endothelial cells by glycoliposomes targeted to E-selectin. Received 16 October 2000; revised 29 November 2000; accepted 29 November 2000     

MicroRNAs in breast cancer initiation and progression

The emerging role of microRNAs (miRNAs) in the epigenetic regulation of many cellular processes has become recognized in both basic research and translational medicine as an important way that gene expression can be fine-tuned. Breast cancer is the most frequent cancer in women, with about one million new cases diagnosed each year worldwide. Starting with the early work of miRNA profiling, more effort has now been put on functions of miRNAs in normal mammary stem cells, breast cancer initiating cells and metastatic cells, and therapy-resistant cancer cells. Future translational studies may focus on identifying miRNA signatures as cancer biomarkers and developing miRNA-based targeted therapeutics.     

Natriuretic peptide hormones promote radial water movements from the xylem of Tradescantia shoots

Immunological evidence suggests that plants, like vertebrates, contain natriuretic peptides (NPs) and that rat atrial NP (rANP) binds specifically to plant membranes and promotes concentration and conformation-dependent stomatal opening. Stomatal opening and specific increases in cGMP levels were also observed in response to immunoreactive plant NP (irPNP). Here we report that both 1 μM rANP and irPNP (100 ng total protein/100 μL) significantly increase radial water movements out of the xylem of shoots of Tradescantia multiflora. Enhanced radial water movements are also observed in response to the cell permeant cGMP analogue 8-Br-cGMP (100 nM). The water channel inhibitor mercuric chloride (HgCl₂) significantly inhibits radial water movements at concentrations of 50 μM, while the presence of 10 μM 2-hydroxyethylmercaptoethanol (ME) prevents the inhibitory effect of the mercurial. The guanylate cyclase inhibitor LY 83583 at a concentration of 20 μM and sodium azide (NaN₃) at concentrations of ≥ 1 μM both also reduce radial water movements. We therefore conclude that the regulation of radial water movement out of the xylem involves modulation of cGMP levels, water channels and respiration-dependent processes. In addition, we propose that NPs have a critical role to play in radial water movements out of the xylem and speculate that as in vertebrates, NP effects might, at least in part, be mediated via the regulation of guanylate cyclases and water channels. Received 15 June 1998; received after revision 7 August 1998; accepted 26 August 1998     

Arginine-rich cell penetrating peptides: from endosomal uptake to nuclear delivery

Delivery of macromolecules into living cells by arginine-rich cell penetrating peptides (AR-CPPs) is an important new avenue for the development of novel therapeutic strategies. However, to date the mechanism of this delivery remains elusive. Recent data implicate endocytosis in the internalization of AR-CPPs and their macromolecular cargo and also indicate limited delivery of macromolecules into the cell cytoplasm and nucleus. Different types of endocytosis – clathrin-dependent endocytosis, raft/caveolin-dependent endocytosis and macropinocytosis – are all implicated in the uptake of AR-CPPs and their cargo into different cells. Cationic AR-CPPs dramatically increase uptake of conjugated molecules through efficient binding to surface proteoglycans. Whether this increase in binding can assure delivery of a sufficient amount of functionally active macromolecules into the cytoplasm and nucleus or whether there is a specific mechanism by which AR-CPPs facilitate the escape of conjugated cargo from endosomes remains to be understood. Received 30 June 2005; received after revision 9 August 2005; accepted 30 August 2005     

Diagnostic and therapeutic applications of azulenyl nitrone spin traps

Azulenyl nitrones have been recently demonstrated to constitute a new class of nitrone-based spin traps with the unprecedented capacity to tag free radicals by yielding characteristically colored and highly visible diamagnetic (and paramagnetic) spin adducts. In addition, a comparison of the oxidation potentials of azulenyl nitrones such as 1 and congeners to those of conventional nitrone spin traps previously investigated as potential antioxidant therapeutics such as N-tert-butyl-alpha-phenylnitrone and its related ortho-sodium sulfonate reveals that the azulene-derived spin traps are far more readily oxidized. These special features render azulenyl nitrones of interest with regard to both their distinct ability to engender the convenient use of colorimetric detection to monitor free radical-mediated oxidative stress in biological systems, and to their potentially enhanced efficacy as neuroprotective antioxidants vs. those conventional nitrone spin traps earlier examined as such. Herein is reported an overview of recent developments pertaining to the use of azulenyl nitrones in the detection of oxidative stress in animal models of amyotrophic lateral sclerosis and stroke, and to their neuroprotective activity in animal models of Parkinson's disease, stroke and neurodegeneration within the retina.     

A combined artificial chromosome-stem cell therapy method in a model experiment aimed at the treatment of Krabbe’s disease in the Twitcher mouse

Mammalian artificial chromosomes (MACs) are safe, stable, non-integrating genetic vectors with almost unlimited therapeutic transgene-carrying capacity. The combination of MAC and stem cell technologies offers a new strategy for stem cell-based therapy, the efficacy of which was confirmed and validated by using a mouse model of a devastating monogenic disease, galactocerebrosidase deficiency (Krabbe’s disease). Therapeutic MACs were generated by sequence-specific loading of galactocerebrosidase transgenes into a platform MAC, and stable, pluripotent mouse embryonic stem cell lines were established with these chromosomes. The transgenic stem cells were thoroughly characterized and used to produce chimeric mice on the mutant genetic background. The lifespan of these chimeras was increased twofold, verifying the feasibility of the development of MAC-stem cell systems for the delivery of therapeutic genes in stem cells to treat genetic diseases and cancers, and to produce cell types for cell replacement therapies. Received 29 July 2008; received after revision 22 September 2008; accepted 24 September 2008     

Prolyl endopeptidases

This review describes the structure and function of prolyl endopeptidase (PEP) enzymes and how they are being evaluated as drug targets and therapeutic agents. The most well studied PEP family has a two-domain structure whose unique seven-blade β-propeller domain works with the catalytic domain to hydrolyze the peptide bond on the carboxyl side of internal proline residues of an oligopeptide substrate. Structural and functional studies on this protease family have elucidated the mechanism for peptide entry between the two domains. Other structurally unrelated PEPs have been identified, but have not been studied in detail. Human PEP has been evaluated as a pharmacological target for neurological diseases due to its high brain concentration and ability to cleave neuropeptides in vitro. Recently, microbial PEPs have been studied as potential therapeutics for celiac sprue, an inflammatory disease of the small intestine triggered by proline-rich gluten. Received 6 July 2006; received after revision 17 August 2006; accepted 1 November 2006     

Inhibitors of protein translocation across membranes of the secretory pathway: novel antimicrobial and anticancer agents

Proteins routed to the secretory pathway start their journey by being transported across biological membranes, such as the endoplasmic reticulum. The essential nature of this protein translocation process has led to the evolution of several factors that specifically target the translocon and block translocation. In this review, various translocation pathways are discussed together with known inhibitors of translocation. Properties of signal peptide-specific systems are highlighted for the development of new therapeutic and antimicrobial applications, as compounds can target signal peptides from either host cells or pathogens and thereby selectively prevent translocation of those specific proteins. Broad inhibition of translocation is also an interesting target for the development of new anticancer drugs because cancer cells heavily depend on efficient protein translocation into the endoplasmic reticulum to support their fast growth.     

瑞替普酶治疗急性心肌梗死（AMI）的临床观察

目的对比观察瑞替普酶（reteplase rPA）与尿激酶用于急性心肌梗死（AMI）溶栓治疗的效果。方法从2006年10月到2008年10月，共收治38例AMI患者，随机接受r—PA或尿激酶溶栓治疗，观察溶栓再通率及不良反应发生率。结果溶栓后2h再通率rPA组为89．47％，尿激酶组68．42％（P〈0．01）。结论瑞替普酶治疗AMI再通率高，疗效确切，值得临床推广。     

Sulfatide-tenascin interaction mediates binding to the extracellular matrix and endocytic uptake of liposomes in glioma cells

Tenascin-C is an extracellular matrix glycoprotein, whose expression is highly restricted in normal adult tissues, but markedly up-regulated in a range of tumors, and therefore serves as a potential receptor for targeted anticancer drug or gene delivery. We describe here a liposomal carrier system in which the targeting ligand is sulfatide. Experiments with tenascin-C-expressing glioma cells demonstrated that binding of liposomes to the extracellular matrix relied essentially on the sulfatide-tenascin-C interaction. Following binding to the extracellular matrix, the sulfatide-containing liposomes were internalized via both caveolae/lipid raft- and clathrin-dependent pathways, which would ensure direct cytoplasmic release of the cargoes carried in the liposomes. Such natural lipid-guided intracellular delivery targeting at the extracellular matrix glycoproteins of tumor cells thus opens a new direction for development of more effective anticancer chemotherapeutics in future. K. Shao & Q. Hou: These authors contributed equally to this work. Received 22 September 2006; received after revision 5 December 2006; accepted 9 January 2007