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The Role of Branch Cell Symmetry and Other Critical Nanoscale Design Parameters in the Determination of Dendrimer Encapsulation Properties. Biomolecules 2020; 10:biom10040642. [PMID: 32326311 PMCID: PMC7226492 DOI: 10.3390/biom10040642] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/27/2020] [Accepted: 03/21/2020] [Indexed: 12/23/2022] Open
Abstract
This article reviews progress over the past three decades related to the role of dendrimer-based, branch cell symmetry in the development of advanced drug delivery systems, aqueous based compatibilizers/solubilizers/excipients and nano-metal cluster catalysts. Historically, it begins with early unreported work by the Tomalia Group (i.e., The Dow Chemical Co.) revealing that all known dendrimer family types may be divided into two major symmetry categories; namely: Category I: symmetrical branch cell dendrimers (e.g., Tomalia, Vögtle, Newkome-type dendrimers) possessing interior hollowness/porosity and Category II: asymmetrical branch cell dendrimers (e.g., Denkewalter-type) possessing no interior void space. These two branch cell symmetry features were shown to be pivotal in directing internal packing modes; thereby, differentiating key dendrimer properties such as densities, refractive indices and interior porosities. Furthermore, this discovery provided an explanation for unimolecular micelle encapsulation (UME) behavior observed exclusively for Category I, but not for Category II. This account surveys early experiments confirming the inextricable influence of dendrimer branch cell symmetry on interior packing properties, first examples of Category (I) based UME behavior, nuclear magnetic resonance (NMR) protocols for systematic encapsulation characterization, application of these principles to the solubilization of active approved drugs, engineering dendrimer critical nanoscale design parameters (CNDPs) for optimized properties and concluding with high optimism for the anticipated role of dendrimer-based solubilization principles in emerging new life science, drug delivery and nanomedical applications.
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Vekariya PA, Karia PS, Bhatt BS, Patel MN. Spectroscopic and electrochemical study for evaluating DNA interaction activity of 4‐(3‐halophenyl)‐6‐(pyridin‐2‐yl)pyrimidin‐2‐amine based piano stool Cp* Rh (III) and Ir (III) complexes. Appl Organomet Chem 2019. [DOI: 10.1002/aoc.5152] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
| | - Parag S. Karia
- Department of ChemistrySardar Patel University Vallabh Vidyanagar 388 120 Gujarat India
| | - Bhupesh S. Bhatt
- Department of ChemistrySardar Patel University Vallabh Vidyanagar 388 120 Gujarat India
| | - Mohan N. Patel
- Department of ChemistrySardar Patel University Vallabh Vidyanagar 388 120 Gujarat India
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Effect of Substituents on the Biological Activities of Piano Stool η5-Cyclopentadienyl Rh(III) and Ir(III) Complexes. J Inorg Organomet Polym Mater 2018. [DOI: 10.1007/s10904-018-0957-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Vekariya PA, Karia PS, Bhatt BS, Patel MN. Half Sandwich Rhodium(III) and Iridium(III) Complexes as Cytotoxic and Metallonuclease Agents. Appl Biochem Biotechnol 2018; 187:556-569. [PMID: 30003473 DOI: 10.1007/s12010-018-2835-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 07/02/2018] [Indexed: 12/28/2022]
Abstract
Half sandwich complexes of the type [(η5-C5Me5)M(L1-3)Cl]Cl.2H2O were synthesized using [{(η5-C5Me5)M(μ-Cl)Cl}2], where M = Rh(III)/Ir(III) and L1-3 = pyrimidine-based ligands. The complexes were characterized by spectral analysis. DNA interaction studies by absorption titration and hydrodynamic measurement and suggest intercalative mode of binding of complexes with CT-DNA. The molecular docking study also supports intercalation of the complexes between the stacks of nucleotide base pairs. The gel electrophoresis assay demonstrated the ability of the complexes to interact and cleave plasmid DNA. Minimum inhibitory concentrations (MIC) of the complexes were investigated by the microdilution broth method. The cytotoxic properties of the metal complexes were evaluated using brine shrimp lethality bioassay.
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Affiliation(s)
- Pankajkumar A Vekariya
- Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Gujarat, 388120, India
| | - Parag S Karia
- Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Gujarat, 388120, India
| | - Bhupesh S Bhatt
- Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Gujarat, 388120, India
| | - Mohan N Patel
- Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Gujarat, 388120, India.
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Suppression of Sympathetic Nerve Sprouting by Local Administration of an α-antagonist Around the Dorsal Root Ganglion in a Lumbar Radiculopathy Model. Spine (Phila Pa 1976) 2018; 43:E321-E326. [PMID: 28723879 DOI: 10.1097/brs.0000000000002333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Animal experimental study with intervention. OBJECTIVE The purpose of this study was to elucidate whether local administration of an α-antagonist around the dorsal root ganglion (DRG) suppressed sympathetic nerve sprouting, from the acute to the chronic pain development phase, in a lumbar radiculopathy model using immunohistochemical methods. SUMMARY OF BACKGROUND DATA The abnormal sympathetic-somatosensory interaction may underlie some forms of neuropathic pain. There were several reports suggesting α-antagonists are effective to treat neuropathic pain. However, its pathophysiological mechanisms remain obscure. METHODS We used 70 male Sprague-Dawley rats. After root constriction (RC), rats received a series of three local injections of the nonselective α-antagonist phentolamine around the DRG for 3 days. There were three groups of rats: those that were injected from the day of surgery and those injected from day 4 and third group injected from day 11. The control rats were subjected to RC but equal-volume normal saline injections, and the naïve rats were not subjected to any surgical procedures. At the 14th postoperative day, the left L5 DRG was removed, embedded in paraffin, and sectioned. Sections were then immunostained with antibodies to tyrosine hydroxylase (TH). To quantify the extent of the presence of sympathetic nerve fibers, we counted TH-immunoreactive fibers in the DRG using a light microscope equipped with a micrometer graticule. We counted the squares of the graticule, which contained TH-immunoreactive fibers for each of five randomly selected sections of the DRG. RESULTS In the naïve group, TH-immunoreactive fibers were scarce in the DRG. α-antagonist injections from postoperative day 0 and 4 suppressed sympathetic nerve sprouting compared with the control group. α-antagonist injections from postoperative day 11 had no suppressant effect compared with the control group. CONCLUSION The α-antagonist administered around the DRG could suppress neural plastic changes in the early phase after nerve injury. LEVEL OF EVIDENCE N/A.
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Elkin I, Banquy X, Barrett CJ, Hildgen P. Non-covalent formulation of active principles with dendrimers: Current state-of-the-art and prospects for further development. J Control Release 2017; 264:288-305. [DOI: 10.1016/j.jconrel.2017.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/28/2017] [Accepted: 09/01/2017] [Indexed: 12/18/2022]
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Duan X, He C, Kron SJ, Lin W. Nanoparticle formulations of cisplatin for cancer therapy. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2016; 8:776-91. [PMID: 26848041 PMCID: PMC4975677 DOI: 10.1002/wnan.1390] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 12/16/2015] [Accepted: 12/27/2015] [Indexed: 12/12/2022]
Abstract
The genotoxic agent cisplatin, used alone or in combination with radiation and/or other chemotherapeutic agents, is an important first-line chemotherapy for a broad range of cancers. The clinical utility of cisplatin is limited both by intrinsic and acquired resistance and dose-limiting normal tissue toxicity. That cisplatin shows little selectivity for tumor versus normal tissue may be a critical factor limiting its value. To overcome the low therapeutic ratio of the free drug, macromolecular, liposomal, and nanoparticle drug delivery systems have been explored toward leveraging the enhanced permeability and retention effect and promoting delivery of cisplatin to tumors. Here, we survey recent advances in nanoparticle formulations of cisplatin, focusing on agents that show promise in preclinical or clinical settings. WIREs Nanomed Nanobiotechnol 2016, 8:776-791. doi: 10.1002/wnan.1390 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Xiaopin Duan
- Department of Chemistry, University of Chicago, 929 E 57 St, Chicago, IL 60637, USA
| | - Chunbai He
- Department of Chemistry, University of Chicago, 929 E 57 St, Chicago, IL 60637, USA
| | - Stephen J. Kron
- Department of Molecular Genetics and Cell Biology, University of Chicago, 929 E 57 St, Chicago, IL 60637, USA
| | - Wenbin Lin
- Department of Chemistry, University of Chicago, 929 E 57 St, Chicago, IL 60637, USA
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Callari M, Aldrich-Wright JR, de Souza PL, Stenzel MH. Polymers with platinum drugs and other macromolecular metal complexes for cancer treatment. Prog Polym Sci 2014. [DOI: 10.1016/j.progpolymsci.2014.05.002] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Oberoi HS, Nukolova NV, Kabanov AV, Bronich TK. Nanocarriers for delivery of platinum anticancer drugs. Adv Drug Deliv Rev 2013; 65:1667-85. [PMID: 24113520 PMCID: PMC4197009 DOI: 10.1016/j.addr.2013.09.014] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 09/19/2013] [Accepted: 09/25/2013] [Indexed: 12/18/2022]
Abstract
Platinum based anticancer drugs have revolutionized cancer chemotherapy, and continue to be in widespread clinical use especially for management of tumors of the ovary, testes, and the head and neck. However, several dose limiting toxicities associated with platinum drug use, partial anti-tumor response in most patients, development of drug resistance, tumor relapse, and many other challenges have severely limited the patient quality of life. These limitations have motivated an extensive research effort towards development of new strategies for improving platinum therapy. Nanocarrier-based delivery of platinum compounds is one such area of intense research effort beginning to provide encouraging preclinical and clinical results and may allow the development of the next generation of platinum chemotherapy. This review highlights current understanding on the pharmacology and limitations of platinum compounds in clinical use, and provides a comprehensive analysis of various platinum-polymer complexes, micelles, dendrimers, liposomes and other nanoparticles currently under investigation for delivery of platinum drugs.
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Affiliation(s)
- Hardeep S. Oberoi
- Department of Pharmaceutical Sciences and Center for Drug Delivery and Nanomedicine, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Natalia V. Nukolova
- Department of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119992, Russia
- Russian State Medical University, Department of Medical Nanobiotechnology, Ostrovityanova 1, Moscow 117997, Russia
| | - Alexander V. Kabanov
- Department of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119992, Russia
- Center for Nanotechnology in Drug Delivery and Division of Molecular Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, NC 27599, USA
| | - Tatiana K. Bronich
- Department of Pharmaceutical Sciences and Center for Drug Delivery and Nanomedicine, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198, USA
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Binauld S, Scarano W, Stenzel MH. pH-Triggered Release of Platinum Drugs Conjugated to Micelles via an Acid-Cleavable Linker. Macromolecules 2012. [DOI: 10.1021/ma3012812] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Sandra Binauld
- Centre for Advanced Macromolecular
Design (CAMD), University of New South Wales, Sydney, NSW 2052, Australia
| | - Wei Scarano
- Centre for Advanced Macromolecular
Design (CAMD), University of New South Wales, Sydney, NSW 2052, Australia
| | - Martina H. Stenzel
- Centre for Advanced Macromolecular
Design (CAMD), University of New South Wales, Sydney, NSW 2052, Australia
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Kaminskas LM, McLeod VM, Porter CJH, Boyd BJ. Association of chemotherapeutic drugs with dendrimer nanocarriers: an assessment of the merits of covalent conjugation compared to noncovalent encapsulation. Mol Pharm 2012; 9:355-73. [PMID: 22250750 DOI: 10.1021/mp2005966] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cancer is a leading cause of death within developed nations, and part of this morbidity is due to difficulties associated with its treatment. Currently, anticancer therapy relies heavily upon the administration of small molecule cytotoxic drugs that attack both cancerous and noncancerous cells due to limited selectivity of the drugs and widespread distribution of the cytotoxic molecules throughout the body. The antitumor efficacy and systemic toxicity of existing chemotherapeutic drugs can, however, be improved by employing formulation and particle engineering approaches. Thus, drug delivery systems can be developed that more specifically target tumor tissue using both passive (such as the enhanced permeation and retention effect) and active (through the use of cancer targeting ligands) modalities. Dendrimers are one such system that can be developed with high structural monodispersity, long plasma circulation times and precise control over surface structure and biodistribution properties. Chemotherapeutic drugs can be associated with dendrimers via covalent conjugation to the surface, or via encapsulation of drugs within the structure. Each of these approaches has demonstrated therapeutic benefit relative to the administration of free drug. Thus far, however, there has not been a systematic review toward which drug association approach will provide the best outcomes in terms of antitumor efficacy and systemic toxicity. Hence, the current literature is reviewed here and recommendations are proposed as to the suggested approach to develop dendrimers as tumor targeted drug-delivery vectors.
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Affiliation(s)
- Lisa M Kaminskas
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville Campus, 381 Royal Parade, Parkville, Victoria, Australia
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El Kazzouli S, Mignani S, Bousmina M, Majoral JP. Dendrimer therapeutics: covalent and ionic attachments. NEW J CHEM 2012. [DOI: 10.1039/c1nj20459a] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Floyd WC, Datta GK, Imamura S, Kieler-Ferguson HM, Jerger K, Patterson AW, Fox ME, Szoka FC, Fréchet JMJ, Ellman JA. Chemotherapeutic evaluation of a synthetic tubulysin analogue-dendrimer conjugate in c26 tumor bearing mice. ChemMedChem 2011; 6:49-53. [PMID: 20973119 DOI: 10.1002/cmdc.201000377] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Wang J, Ji X, Shi J, Sun H, Jiang H, Liu H. Diastereoselective Michael reaction of chiral nickel(II) glycinate with nitroalkenes for asymmetric synthesis of β-substituted α,γ-diaminobutyric acid derivatives in water. Amino Acids 2011; 42:1685-94. [PMID: 21384130 DOI: 10.1007/s00726-011-0870-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 02/22/2011] [Indexed: 10/18/2022]
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van der Poll DG, Kieler-Ferguson HM, Floyd WC, Guillaudeu SJ, Jerger K, Szoka FC, Fréchet JM. Design, synthesis, and biological evaluation of a robust, biodegradable dendrimer. Bioconjug Chem 2010; 21:764-73. [PMID: 20353169 DOI: 10.1021/bc900553n] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
PEGylated dendrimers are attractive for biological applications due to their tunable pharmacokinetics and ability to carry multiple copies of bioactive molecules. The rapid and efficient synthesis of a robust and biodegradable PEGylated dendrimer based on a polyester-polyamide hybrid core is described. The architecture is designed to avoid destructive side reactions during dendrimer preparation while maintaining biodegradability. Therefore, a dendrimer functionalized with doxorubicin (Dox) was prepared from commercial starting materials in nine, high-yielding linear steps. Both the dendrimer and Doxil were evaluated in parallel using equimolar dosage in the treatment of C26 murine colon carcinoma, leading to statistically equivalent results with most mice tumor-free at the end of the 60 day experiment. The attractive features of this dendritic drug carrier are its simple synthesis, biodegradability, and versatility for application to a variety of drug payloads with high drug loadings.
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Affiliation(s)
- Derek G van der Poll
- College of Chemistry, University of California, Berkeley, California 94720-1460, USA
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Haxton KJ, Burt HM. Polymeric drug delivery of platinum-based anticancer agents. J Pharm Sci 2009; 98:2299-316. [PMID: 19009590 DOI: 10.1002/jps.21611] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Platinum-based anticancer agents such as cisplatin and carboplatin are in widespread clinical use but associated with many side effects. Improving the delivery of cytotoxic platinum compounds may lead to reduced side effects and achieve greater efficacy at lower doses. Polymer-based therapeutics have been investigated as potential drug delivery vehicles for platinum-based drugs. Against a background of the chemistry and pharmacology of cytotoxic platinum compounds, this review discusses the formation and properties of platinum-polymer complexes, dendrimers, micelles, and microparticulates.
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Affiliation(s)
- Katherine J Haxton
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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Affiliation(s)
- Rakesh Kumar Tekade
- Pharmaceutics Research Laboratory, Department of Pharmaceutical Sciences, Dr. Hari Singh Gour University, Sagar-470 003, India
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El-Shehawy AA, Sugiyama K, Hirao A. Convenient approaches for the synthesis and characterization of well-defined linear-dendritic diblock copolymers having a definite number of peripheral primary amino groups: Exact control of numbers introduced and dendritic distribution to enhance co-operative effect. REACT FUNCT POLYM 2008. [DOI: 10.1016/j.reactfunctpolym.2008.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Krause-Heuer AM, Grant MP, Orkey N, Aldrich-Wright JR. Drug Delivery Devices and Targeting Agents for Platinum(II) Anticancer Complexes. Aust J Chem 2008. [DOI: 10.1071/ch08157] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An ideal platinum-based delivery device would be one that selectively targets cancerous cells, can be systemically delivered, and is non-toxic to normal cells. It would be beneficial to provide drug delivery devices for platinum-based anticancer agents that exhibit high drug transport capacity, good water solubility, stability during storage, reduced toxicity, and enhanced anticancer activity in vivo. However, the challenges for developing drug delivery devices include carrier stability in vivo, the method by which extracellular or intracellular drug release is achieved, overcoming the various mechanisms of cell resistance to drugs, controlled drug release to cancer cells, and platinum drug bioavailability. There are many potential candidates under investigation including cucurbit[n]urils, cyclodextrins, calix[n]arenes, and dendrimers, with the most promising being those that are synthetically adaptable enough to attach to targeting agents.
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Haxton KJ, Burt HM. Hyperbranched polymers for controlled release of cisplatin. Dalton Trans 2008:5872-5. [DOI: 10.1039/b809949a] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mizuno S, Takebayashi T, Kirita T, Tanimoto K, Tohse N, Yamashita T. The effects of the sympathetic nerves on lumbar radicular pain. ACTA ACUST UNITED AC 2007; 89:1666-72. [DOI: 10.1302/0301-620x.89b12.19258] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A rat model of lumbar root constriction with an additional sympathectomy in some animals was used to assess whether the sympathetic nerves influenced radicular pain. Behavioural tests were undertaken before and after the operation. On the 28th post-operative day, both dorsal root ganglia and the spinal roots of L4 and L5 were removed, frozen and sectioned on a cryostat (8 μm to 10 μm). Immunostaining was then performed with antibodies to tyrosine hydroxylase (TH) according to the Avidin Biotin Complex method. In order to quantify the presence of sympathetic nerve fibres, we counted TH-immunoreactive fibres in the dorsal root ganglia using a light microscope equipped with a micrometer graticule (10 x 10 squares, 500 mm x 500 mm). We counted the squares of the graticule which contained TH-immunoreactive fibres for each of five randomly-selected sections of the dorsal root ganglia. The root constriction group showed mechanical allodynia and thermal hyperalgesia. In this group, TH-immunoreactive fibres were abundant in the ipsilateral dorsal root ganglia at L5 and L4 compared with the opposite side. In the sympathectomy group, mechanical hypersensitivity was attenuated significantly. We consider that the sympathetic nervous system plays an important role in the generation of radicular pain.
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Affiliation(s)
| | | | | | | | - N. Tohse
- Department of Cellular Physiology and Signal Transduction School of Medicine Sapporo Medical University, South 1, West 16 & 17, Chuo-ku, Sapporo 060–8543, Japan
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