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Sample records for radiolabelled peptide analogues

  1. Targeted Melanoma Imaging and Therapy with Radiolabeled Alpha-Melanocyte Stimulating Hormone Peptide Analogues

    PubMed Central

    Quinn, Thomas; Zhang, Xiuli; Miao, Yubin

    2010-01-01

    Radiolabeled alpha-melanocyte stimulating hormone (α-MSH) analogues have been used to define the expression, affinity and function of the melanocortin-1 receptor (MC1-R). The MC1-R is one of a family of five G-protein linker receptors, which is primarily involved in regulation of skin pigmentation. Over-expression of the MC1-R on melanoma tumor cells has made it an attractive target for the development of α-MSH peptide based imaging and therapeutic agents. Initially, the native α-MSH peptide was radiolabeled directly, but it suffered from low specific activity and poor stability. The addition of non-natural amino acids yielded α-MSH analogues with greater MC-1R affinity and stability. Furthermore, peptide cyclization via disulfide and lactam bond formation as well as site-specific metal coordination resulted in additional gains in receptor affinity and peptide stability in vitro and in vivo. Radiochemical stability of the α-MSH analogues was improved through the conjugation of metal chelators to the peptide’s N-terminus or lysine residues for radionuclide coordination. In vitro cell binding studies demonstrated that the radiolabeled α-MSH analogues had low to subnanomolar affinities for the MC1-R. Biodistribution and imaging studies in the B16 mouse melanoma modeled showed rapid tumor uptake of the radiolabeled peptides, with the cyclic peptides demonstrating prolonged tumor retention. Cyclic α-MSH analogues labeled with beta and alpha emitting radionuclides demonstrated melanoma therapeutic efficacy in the B16 melanoma mouse model. Strong pre-clinical imaging and therapy data highlight the clinical potential use of radiolabeled α-MSH peptides for melanoma imaging and treatment of disseminated disease. PMID:20467398

  2. Effect of lipophilicity on the pharmacokinetics of radiolabeled spiperone analogues

    SciTech Connect

    Moerlein, S.M.; Laufer, P.; Stocklin, G.

    1985-05-01

    Several radiolabeled analogues of the butyrophenone neuroleptic spiperone exhibit in vivo localization in D/sub 2/ receptor-rich areas of the brain. A series of N-alkylated spiperone analogues and the corresponding p-brominated compounds were synthesized to ascertain the optimum structure for labeling with /sup 18/F or /sup 75/Br. In vivo studies indicated that all analogues had D/sub 2/ receptor-binding affinity within the same order of magnitude (IC/sub 50/=2.6 nM for SP and 3.9 nM for BPSP), whereas the lipophilicity varied greatly (log P=2.7 for SP and 5.2 for BPSP). In vivo studies in the rat using the radiobrominated analogues were done using compounds labeled with n.c.a. /sup 77/Br via in-situ oxidation by dichloramine-T or H/sub 2/O/sub 2//CH/sub 3/COOH. Alkylation of BSP was found to decrease the striatum-to-cerebellum concentration at 6 hr from 8.2 for BSP to 5.2 for BPSP. Unexpectedly, the cerebral uptake did not increase with log P, the striatal concentration dropping from 390% MBC for BSP to 85% MBC for BPSP. This contrasts with previous results for SP and MSP, where the brain uptake increases slightly with log P. Increasing lipophilicity increases blood faster than brain concentrations, and it is concluded that whereas N-alkylation may be beneficial for /sup 18/F-labeld neuroleptics, non-alkylated spiperone is the optimum labeling substrate for /sup 75/Br.

  3. Radiolabeled peptides in oncology: role in diagnosis and treatment.

    PubMed

    Weiner, Ronald E; Thakur, Mathew L

    2005-01-01

    There has been an exponential growth in the development of radiolabeled peptides for diagnostic and therapeutic applications in the last decade. The automated means of synthesizing these compounds in large quantities and the simplified methods of purifying, characterizing, and optimizing them have kindled attention to peptides as carrier molecules. These new techniques have accelerated the commercial development of radiolabelled peptides, which has provided additional radiopharmaceuticals for the nuclear medicine community. Peptides have many key properties including fast clearance, rapid tissue penetration, and low antigenicity, and can be produced easily and inexpensively. However, there may be problems with in vivo catabolism, unwanted physiologic effects, and chelate attachment. Radiolabeled peptides have made their greatest impact in the management of relatively rare neuroendocrine malignancies. Indeed, Indium-111 ((111)In)-pentetreotide ((111)In-DTPA-octreotide, Octreoscan), which binds to somatostatin receptors (SSTRs), has become the diagnostic 'gold standard' in these diseases. However, (111)In-pentetreotide has been less successful in the diagnosis of other more prevalent diseases in which SSTRs are upregulated. Technetium-99m (99mTc)-depreotide (NeoTect), a 99mTc-labeled SSTR-analog, could have wider impact since it has high sensitivity and specificity for lung cancer lesion detection. However, this impact may be minimized by the increased availability of positron emission tomography imaging with Fluorine-18 (18F)-flourodeoxyglucose, which has similar sensitivity and specificity for lesion identification in this disease, and is currently more widely used. The receptors for bombesin, alpha-melanocyte-stimulating hormone, neurotensin, and the integrin alpha(v)beta3, are under active investigation as targets for radiolabelled peptides, but are still in the pre-clinical stage. Compounds directed at the cholecystokinin-B/gastrin receptor have shown promising

  4. Radiolabelled GLP-1 analogues for in vivo targeting of insulinomas.

    PubMed

    Brom, Maarten; Joosten, Lieke; Oyen, Wim J G; Gotthardt, Martin; Boerman, Otto C

    2012-01-01

    Internalizing agonists are usually selected for peptide receptor targeting. There is increasing evidence that non-internalizing receptor antagonists can be used for this purpose. We investigated whether the glucagon-like peptide-1 receptor (GLP-1R) antagonist exendin(9-39) can be used for in vivo targeting of GLP-1R expressing tumours and compared the in vitro and in vivo characteristics with the GLP-1R agonists exendin-3 and exendin-4. The binding and internalization kinetics of labelled [Lys(40) (DTPA)]exendin-3, [Lys(40) (DTPA)]exendin-4 and [Lys(40) (DTPA)]exendin(9-39) were determined in vitro using INS-1 cells. The in vivo targeting properties of [Lys(40) ((111) In-DTPA)]exendin-3, [Lys(40) ((111) In-DTPA)]exendin-4 and [Lys(40) ((111) In-DTPA)]exendin(9-39) were examined in BALB/c nude mice with subcutaneous INS-1 tumours. (nat) In-labelled [Lys(40) (DTPA)]exendin-3, [Lys(40) (DTPA)]exendin-4 and [Lys(40) (DTPA)]exendin(9-39) exhibited similar IC(50) values (13.5, 14.4 and 13.4 n m, respectively) and bound to 26 × 10(3) , 41 × 10(3) and 37 × 10(3) receptors per cell, respectively. [Lys(40) ((111) In-DTPA)]exendin-3 and [Lys(40) ((111) In-DTPA)]exendin-4 showed rapid in vitro binding and internalization kinetics, whereas [Lys(40) ((111) In-DTPA)]exendin(9-39) showed lower binding and minimal internalization in vitro. In mice, high specific uptake of [Lys(40) ((111) In-DTPA)]exendin-3 [25.0 ± 6.0% injected dose (ID) g(-1) ] in the tumour was observed at 0.5 h post-injection (p.i.) with similar uptake up to 4 h p.i. [Lys(40) ((111) In-DTPA)]exendin-4 showed higher tumour uptake at 1 and 4 h p.i. (40.8 ± 7.0 and 41.9 ± 7.2% ID g(-1), respectively). Remarkably, [Lys(40) ((111) In-DTPA)]exendin(9-39) showed only low specific uptake in the tumour at 0.5 h p.i. (3.2 ± 0.7% ID g(-1)), rapidly decreasing over time. In conclusion, the GLP-1R agonists [Lys(40) (DTPA)]exendin-3 and [Lys(40) (DTPA)]exendin-4 labelled with (111

  5. Glucagonlike Peptide 2 Analogue Teduglutide

    PubMed Central

    Chaturvedi, Lakshmi S.; Basson, Marc D.

    2015-01-01

    IMPORTANCE Short bowel syndrome occurs when a shortened intestine cannot absorb sufficient nutrients or fluids. Teduglutide is a recombinant analogue of human glucagonlike peptide 2 that reduces dependence on parenteral nutrition in patients with short bowel syndrome by promoting enterocytic proliferation, increasing the absorptive surface area. However, enterocyte function depends not only on the number of cells that are present but also on differentiated features that facilitate nutrient absorption and digestion. OBJECTIVE To test the hypothesis that teduglutide impairs human intestinal epithelial differentiation. DESIGN AND SETTING We investigated the effects of teduglutide in the modulation of proliferation and differentiation in human Caco-2 intestinal epithelial cells at a basic science laboratory. This was an in vitro study using Caco-2 cells, a human-derived intestinal epithelial cell line commonly used to model enterocytic biology. EXPOSURE Cells were exposed to teduglutide or vehicle control. MAINOUTCOMESAND MEASURES We analyzed the cell cycle by bromodeoxyuridine incorporation or propidium iodide staining and flow cytometry and measured cell proliferation by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. We used quantitative reverse transcription–polymerase chain reaction to assay the expression of the enterocytic differentiation markers villin, sucrase-isomaltase, glucose transporter 2 (GLUT2), and dipeptidyl peptidase 4 (DPP-4), as well as that of the putative differentiation signals schlafen 12 (SLFN12) and caudal-related homeobox intestine-specific transcription factor (Cdx2). Villin promoter activity was measured by a luciferase-based assay. RESULTS The MTS assay demonstrated that teduglutide increased cell numbers by a mean (SD) of 10% (2%) over untreated controls at a maximal 500nM (n = 6, P < .05). Teduglutide increased bromodeoxyuridine-positive cells vs untreated controls by a mean (SD

  6. Ocular penetration of (/sup 125/I)IVDU, a radiolabeled analogue of bromovinyldeoxyuridine

    SciTech Connect

    Maudgal, P.C.; Verbruggen, A.M.; De Clercq, E.; Busson, R.; Bernaerts, R.; de Roo, M.; Ameye, C.; Missotten, L.

    1985-01-01

    Following topical application of (/sup 125/)IVDU, the radiolabeled analogue of bromovinyldeoxyuridine ((E)-5-(2-bromovinyl)-2'-deoxyuridine), as 0.5% or 0.3% eyedrops, to rabbits, (/sup 125/I)IVDU appeared in the anterior chamber fluid at drug levels well above the minimum concentration (0.01 microgram/mL) required for inhibition of herpes simplex virus type 1 replication. These findings are consistent with the efficacy of 0.5% bromovinyldeoxyuridine eyedrops in the topical treatment of herpes simplex uveitis.

  7. Evaluation of Phosphatidylserine-Binding Peptides Radiolabeled with Fluorine 18 for in vivo Imaging of Apoptosis

    NASA Astrophysics Data System (ADS)

    Kapty, Janice Sarah

    We currently do not have a clinical method to directly assess apoptosis induced by cancer therapies. Phosphatidylserine (PS) is an attractive target for imaging apoptosis since it is on the exterior of the apoptotic cells and PS externalization is an early marker of apoptosis. PS-binding peptides are an attractive option for developing an imaging probe to detect apoptosis using positron emission tomography. In this study we evaluated binding characteristics of PS-binding peptides for ability to bind to PS, radiolabeled PS-binding peptides with fluorine-18, and performed in vitro and in vivo analysis of 18F radiolabeled PS-binding peptides including biodistribution analysis and dynamic PET imaging in a murine tumor model of apoptosis. Four peptides were evaluated for PS binding characteristics using a plate based assay system, a liposome mimic of cell membrane PS presentation, and a cell assay of apoptosis. The results indicate that all four peptides bind to PS and are specific to apoptotic cells. The widely used 18 F prosthetic group N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) and the recently developed N-[6-(4-[ 18F]fluorobenzylidene) aminooxyhexyl]maleimide ([18F]FBAM) were investigated for radiolabeling of two representative phosphatidylserine-binding peptides. The prosthetic groups were compared with respect to required reaction conditions for optimum labeling, radiolabeling yield and chemoselectivity. The N-terminus labeled product produced by reaction of [18F]SFB with binding peptide LIKKPF was produced in 18% radiochemical yield while no N-terminus labeled product could be isolated following [18F]SFB reaction with PDGLSR. When the peptides were modified by addition of a cysteine residue at the N-terminus they provided almost quantitative radiochemical yields with [18F]FBAM. Results indicate that for the peptides in this study, [18F]FBAM is a more useful prosthetic group compared to [18F]SFB due to its excellent chemo-selectivity and high radiochemical

  8. From preclinical development to clinical application: Kit formulation for radiolabelling the minigastrin analogue CP04 with In-111 for a first-in-human clinical trial

    PubMed Central

    Pawlak, Dariusz; Rangger, Christine; Peitl, Petra Kolenc; Garnuszek, Piotr; Maurin, Michał; Ihli, Laura; Kroselj, Marko; Maina, Theodosia; Maecke, Helmut; Erba, Paola; Kremser, Leopold; Hubalewska-Dydejczyk, Alicja; Mikołajczak, Renata; Decristoforo, Clemens

    2016-01-01

    Introduction A variety of radiolabelled minigastrin analogues targeting the cholecystokinin 2 (CCK2) receptor were developed and compared in a concerted preclinical testing to select the most promising radiotracer for diagnosis and treatment of medullary thyroid carcinoma (MTC). DOTA–DGlu–DGlu–DGlu–DGlu–DGlu–DGlu– Ala–Tyr–Gly–Trp–Met–Asp–Phe–NH2 (CP04) after labelling with 111In displayed excellent characteristics, such as high stability, receptor affinity, specific and persistent tumour uptake and low kidney retention in animal models. Therefore, it was selected for further clinical evaluation within the ERA-NET project GRAN-T-MTC. Here we report on the development of a pharmaceutical freeze-dried formulation of the precursor CP04 for a first multi-centre clinical trial with 111In-CP04 in MTC patients. Materials and methods The kit formulation was optimised by adjustment of buffer, additives and radiolabelling conditions. Three clinical grade batches of a final kit formulation with two different amounts of peptide (10 or 50 μg) were prepared and radiolabelled with 111In. Quality control and stability assays of both the kits and the resulting radiolabelled compound were performed by HPLC analysis. Results Use of ascorbic acid buffer (pH 4.5) allowed freeze-drying of the kit formulation with satisfactory pellet-formation. Addition of methionine and gentisic acid as well as careful selection of radiolabelling temperature was required to avoid extensive oxidation of the Met11-residue. Trace metal contamination, in particular Zn, was found to be a major challenge during the pharmaceutical filling process in particular for the 10 μg formulation. The final formulations contained 10 or 50 μg CP04, 25 mg ascorbic acid, 0.5 mg gentisic acid and 5 mg l-methionine. The radiolabelling performed by incubation of 200–250 MBq 111InCl3 at 90 °C for 15 min resulted in reproducible radiochemical purity (RCP) >94%. Kit-stability was proven for >6

  9. Radiolabeled Peptide Scaffolds for PET/SPECT - Optical in Vivo Imaging of Carbohydrate-Lectin Interactions

    SciTech Connect

    Deutscher, Susan

    2014-09-30

    The objective of this research is to develop phage display-selected peptides into radio- and fluoresecently- labeled scaffolds for the multimodal imaging of carbohydrate-lectin interactions. While numerous protein and receptor systems are being explored for the development of targeted imaging agents, the targeting and analysis of carbohydrate-lectin complexes in vivo remains relatively unexplored. Antibodies, nanoparticles, and peptides are being developed that target carbohydrate-lectin complexes in living systems. However, antibodies and nanoparticles often suffer from slow clearance and toxicity problems. Peptides are attractive alternative vehicles for the specific delivery of radionuclides or fluorophores to sites of interest in vivo, although, because of their size, uptake and retention may be less than antibodies. We have selected high affinity peptides that bind a specific carbohydrate-lectin complex involved in cell-cell adhesion and cross-linking using bacteriophage (phage) display technologies (1,2). These peptides have allowed us to probe the role of these antigens in cell adhesion. Fluorescent versions of the peptides have been developed for optical imaging and radiolabeled versions have been used in single photon emission computed tomography (SPECT) and positron emission tomography (PET) in vivo imaging (3-6). A benefit in employing the radiolabeled peptides in SPECT and PET is that these imaging modalities are widely used in living systems and offer deep tissue sensitivity. Radiolabeled peptides, however, often exhibit poor stability and high kidney uptake in vivo. Conversely, optical imaging is sensitive and offers good spatial resolution, but is not useful for deep tissue penetration and is semi-quantitative. Thus, multimodality imaging that relies on the strengths of both radio- and optical- imaging is a current focus for development of new in vivo imaging agents. We propose a novel means to improve the efficacy of radiolabeled and fluorescently

  10. Analogue peptides for the immunotherapy of human acute myeloid leukemia.

    PubMed

    Hofmann, Susanne; Mead, Andrew; Malinovskis, Aleksandrs; Hardwick, Nicola R; Guinn, Barbara-Ann

    2015-11-01

    The use of peptide vaccines, enhanced by adjuvants, has shown some efficacy in clinical trials. However, responses are often short-lived and rarely induce notable memory responses. The reason is that self-antigens have already been presented to the immune system as the tumor develops, leading to tolerance or some degree of host tumor cell destruction. To try to break tolerance against self-antigens, one of the methods employed has been to modify peptides at the anchor residues to enhance their ability to bind major histocompatibility complex molecules, extending their exposure to the T-cell receptor. These modified or analogue peptides have been investigated as stimulators of the immune system in patients with different cancers with variable but sometimes notable success. In this review we describe the background and recent developments in the use of analogue peptides for the immunotherapy of acute myeloid leukemia describing knowledge useful for the application of analogue peptide treatments for other malignancies.

  11. In Vivo Imaging with an αvβ6 Specific Peptide Radiolabeled using 18F-“Click” Chemistry: Evaluation and Comparison with the Corresponding 4-[18F]Fluorobenzoyl- and 2-[18F]Fluoropropionyl-Peptides

    PubMed Central

    Hausner, Sven H.; Marik, Jan; Gagnon, M. Karen J.; Sutcliffe, Julie L.

    2009-01-01

    Numerous radiolabeled peptides have been utilized for in vivo imaging of a variety of cell-surface receptors. For applications in PET using [18F]fluorine, peptides are radiolabeled via a prosthetic group approach. We previously developed solution-phase 18F-“click” radiolabeling and solid-phase radiolabeling using 4-[18F]fluorobenzoic and 2-[18F]fluoropropionic acids. Here we compare the 3 different radiolabeling approaches and report the effects on PET imaging and pharmacokinetics. The prosthetic groups did have an influence; metabolites with significantly different polarities were observed. PMID:18785727

  12. Antitumoral cyclic peptide analogues of chlamydocin.

    PubMed

    Bernardi, E; Fauchere, J L; Atassi, G; Viallefont, P; Lazaro, R

    1993-01-01

    A series of cyclic tetrapeptides bearing the bioactive alkylating group on an epsilon-amino-lysyl function have been examined for their antitumoral activity on L1210 and P388 murine leukemia cell lines. One analogue belonging to the chlamydocin family and bearing a beta-chloroethylnitrosourea group was found to be potent at inhibiting L1210 cell proliferation and had a higher therapeutic index than the reference compound bis-beta-chloroethylnitrosourea (BCNU) on the in vivo P388-induced leukemia model.

  13. Antimicrobial and antibiofilm activity of quorum sensing peptides and Peptide analogues against oral biofilm bacteria.

    PubMed

    LoVetri, Karen; Madhyastha, Srinivasa

    2010-01-01

    Widespread antibiotic resistance is a major incentive for the investigation of novel ways to treat or prevent infections. Much effort has been put into the discovery of peptides in nature accompanied by manipulation of natural peptides to improve activity and decrease toxicity. The ever increasing knowledge about bacteria and the discovery of quorum sensing have presented itself as another mechanism to disrupt the infection process. We have shown that the natural quorum sensing (QS) peptide, competence-stimulating peptide (CSP), used by the caries causing bacteria Streptococcus mutans when used in higher than normally present concentrations can actually contribute to cell death in S. mutans. Using an analogue of this quorum sensing peptide (KBI-3221), we have shown it to be beneficial at decreasing biofilm of various Streptococcus species. This chapter looks at a number of assay methods to test the inhibitory effects of quorum sensing peptides and their analogues on the growth and biofilm formation of oral bacteria.

  14. Novel indium-111 labeled gastrin peptide analogues (MG-CL1-4): synthesis and quality control.

    PubMed

    Naqvi, Syed Ali-Raza; Khan, Zulfiqar Ali; Nagra, Saeed Ahmad; Yar, Muhammad; Sherazi, Tauqir A; Shahzad, Sohail Shahzad; Shah, Syed Qaiser; Mahmood, Nasir; Ishfaq, Malik Muhammad; Mather, Stephen John

    2013-03-01

    Radiolabeled neuropeptides are widely investigated to diagnose and therapy of tumors. These peptides get internalization after binding with particular receptors at the surface of cells and finally move to lysosome. Internalization into tumor cells helps in mapping the infected site. Minigastrin peptide analogues (MG-CL1-4) were synthesised and labeled with 111-In radioisotope under different sets of conditions for imaging CCk-2 receptor bearing tumors. Different parameters such as temperature (80-100°C), pH (4-12), incubation time (5-30 minutes) and dilution effect were investigated to get the maximum labeling yield and stability. The results indicated that MG-CL1-4 is successfully labeled with indium-111 at pH 4.5 with heating at 98°C for 15 minute. At these conditions i.e. heating, pH and incubation minimum oxidized and maximum labeling yield, more than 94 %, was obtained. The labeling stability was studied by incubating the radiolabeled complex for predefined time points in PBSA and blood serum. Results show that more than 90% radiolabeled MG-CL1-4 remained intact.

  15. Radiolabelling, quality control and radiochemical purity assessment of the Octreotide analogue 68Ga DOTA NOC.

    PubMed

    Di Pierro, D; Rizzello, A; Cicoria, G; Lodi, F; Marengo, M; Pancaldi, D; Trespidi, S; Boschi, S

    2008-08-01

    Somatostatin receptors 1-5 are over expressed in neuroendocrine tumours (NETs). 68Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-Octreotide (DOTA NOC), a recent synthesized somatostatin analogue, shows high affinity for those receptors. Herein, modifications of a commercial module for the labelling of DOTA NOC with 68Ga, as well as the assessment of time course of the radiochemical purity variation are described. The evaluation of radiochemical stability was done by two different chromatographic methods: reversed-phase radio HPLC and fast TLC analysis. Labelled compound has been found radiochemically stable within 3h from the end of labelling (EOL) and radiochemical purity was always higher than 99%. After 73 labelling sessions the system showed great reproducibility and high radiochemical yield.

  16. A Novel Method for Direct site-specific Radiolabeling of Peptides Using [18F]FDG

    PubMed Central

    Namavari, Mohammad; Cheng, Zhen; Zhang, Rong; De, Abhijit; Levi, Jelena; Hoerner, Joshua K.; Yaghoubi, Shahriar S.; Syud, Faisal A.; Gambhir, Sanjiv S.

    2009-01-01

    We have used the well-accepted and easily available 2-[18F]Fluoro-2-deoxyglucose ([18F]FDG) positron emission tomography (PET) tracer as a prosthetic group for synthesis of 18F-labeled peptides. We herein report the synthesis of [18F]FDG-RGD (18F labeled linear RGD) and [18F]FDG-cyclo(RGDDYK) (18F labeled cyclic RGD) as examples of the use of [18F]FDG. We have successfully prepared [18F]FDG-RGD and [18F]FDG-cyclo(RGDDYK) in 27.5% and 41% radiochemical yields (decay corrected) respectively. The receptor binding affinity study of FDG-cyclo(RGDDYK) for integrin αvβ3 , using αvβ3 positive U87MG cells confirmed a competitive displacement with 125I-echistatin as a radioligand. The IC50 value for FDG-cyclo(RGDDYK) was determined to be 0.67 ± 0.19µM. High contrast small animal PET images with relatively moderate tumor uptake were observed for [18F]FDG-RGD and [18F]FDG-cyclo(RGDDYK) as PET probes in xenografts models expressing αvβ3 integrin. In conclusion, we have successfully used [18F]FDG as a prosthetic group to prepare 18F]FDG-RGD and [18F]FDG-cyclic[RGDDYK] based on a simple one step radiosynthesis. The one step radiosynthesis methodology consists of chemoselective oxime formation between an aminooxy functionalized peptide and [18F]FDG. The results have implications for radiolabeling of other macromolecules and would lead to a very simple strategy for routine pre-clinical and clinical use. PMID:19226160

  17. Automated module radiolabeling of peptides and antibodies with gallium-68, lutetium-177 and iodine-131.

    PubMed

    De Decker, Mario; Turner, J Harvey

    2012-02-01

    Our objectives were to automate radiolabeling of therapeutic activities for safe, reliable, cost-effective, practical routine preparation of (177)Lu-radiopeptides, (131)I radioimmunotherapeutic agents, and (68)Ga-peptide PET diagnostics and, in particular, minimize radiation exposure to the radiopharmaceutical chemist. Reprogramming and adaptation of a commercially available synthetic module (IBA molecular; Synthera®) allowed high yield, fully automated, in-house radiolabeling of novel therapeutic and diagnostic radiopharmaceuticals under remote shielded sterile conditions. Radiochemical yield and purity was measured by instant thin-layer chromatography and high-performance liquid chromatography. (68)Ga-octreotate and (177)Lu-octreotate were synthesized, resulting in both radiochemical yield and radiochemical purity greater than 99%. Synthesis of (131)I-rituximab resulted in a yield of 60%, with a radiochemical purity greater than 99%. Using 400 MBq (68)GaCl(3) per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 2 and 27 μ Sv, contrasting with automated synthesis exposure of 1.3 and 7.9 μ Sv. Using 8000 MBq (177)LuCl(3) per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 44.7 and 75 μ Sv, contrasting with automated synthesis exposure of 2.5 and 20 μ Sv. Using 6000 MBq (131)I per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 83.7 and 335 μ Sv, contrasting with automated synthesis exposure of 10.9 and 54.7 μ Sv. The reduction in radiation exposure by automated synthesis of radiopharmaceuticals in the Synthera® module was at least five fold. Automated synthesis of therapeutic (177)Lu and (131)I radiopharmaceuticals and (68)Ga PET agents in the shielded sterile Synthera® module is simple, practical, and efficient and virtually eliminates radiation exposure to the radiopharmaceutical chemist.

  18. Transdermal delivery of a melanotropic peptide hormone analogue

    SciTech Connect

    Dawson, B.V.; Hadley, M.E.; Kreutzfeld, K.; Dorr, R.T.; Hruby, V.J.; Al-Obeidi, F.; Don, S.

    1988-01-01

    We previously reported that topical application of (Nl3/sup 4/,D-Phe/sup 7/)alpha-MSH, a superpotent analogue of alpha-melanocyte stimulating hormone, to mice induces a darkening of follicular melanocytes throughout the skin. We now report that the melanotropin analogue can be delivered across mouse but not rat skin in an in vitro model system. Passage of the analogue from the topically applied vehicle (polyethylene glycol) across the skin into a subcutaneous receiving vessel was demonstrated by both bioassay as well as by radioimmunoassay. The bioassay data demonstrate that percutaneous absorption of the melanotropin did not result in loss of biological activity of the peptide. The differential penetration of the peptide across rodent skin reveals that one cannot predict percutaneous absorption of a substance across the stratum corneum from studies on a single species. The present results are the first to demonstrate, by direct quantitative measurements, that a bioactive peptide can be delivered across the vertebrate integument in vitro. These studies point out the potential of a topically applied melanotropin for tanning of the skin and possibly for treatment of certain hypopigmentary disorders.

  19. Synthesis and antioxidant activity of peptide-based ebselen analogues.

    PubMed

    Satheeshkumar, Kandhan; Mugesh, Govindasamy

    2011-04-18

    A series of di- and tripeptide-based ebselen analogues has been synthesized. The compounds were characterized by (1)H, (13)C, and (77)Se NMR spectroscopy and mass spectral techniques. The glutathione peroxidase (GPx)-like antioxidant activity has been studied by using H(2)O(2) , tert-butyl hydroperoxide (tBuOOH), and cumene hydroperoxide (Cum-OOH) as substrates, and glutathione (GSH) as a cosubstrate. Although all the peptide-based compounds have a selenazole ring similar to that of ebselen, the GPx activity of these compounds highly depends on the nature of the peptide moiety attached to the nitrogen atom of the selenazole ring. It was observed that the introduction of a phenylalanine (Phe) amino acid residue in the N-terminal reduces the activity in all three peroxide systems. On the other hand, the introduction of aliphatic amino acid residues such as valine (Val) significantly enhances the GPx activity of the ebselen analogues. The difference in the catalytic activity of dipeptide-based ebselen derivatives can be ascribed mainly to the change in the reactivity of these compounds toward GSH and peroxide. Although the presence of the Val-Ala-CO(2) Me moiety facilitates the formation of a catalytically active selenol species, the reaction of ebselen analogues that has a Phe-Ile-CO(2) Me residue with GSH does not generate the corresponding selenol. To understand the antioxidant activity of the peptide-based ebselen analogues in the absence of GSH, these compounds were studied for their ability to inhibit peroxynitrite (PN)-mediated nitration of bovine serum albumin (BSA) and oxidation of dihydrorhodamine 123. In contrast to the GPx activity, the PN-scavenging activity of the Phe-based peptide analogues was found to be comparable to that of the Val-based compounds. However, the introduction of an additional Phe residue to the ebselen analogue that had a Val-Ala dipeptide significantly reduced the potency of the parent compound in PN-mediated nitration.

  20. Methods to assess the biodistribution of radiolabelled somatostatin analogues and treatment response of neuroendocrine tumours

    NASA Astrophysics Data System (ADS)

    Gnanasegaran, Gopinath

    Introduction: During the past decade, proof of the principle that somatostatin receptors can be successfully used for in vivo targeting of neuroendocrine tumours (NETs) has been provided. These tumours are imaged with 111Indium-pentetreotide and treated with 90Yttrium labeled somatostatin analogues. The aim of this study was to assess (a) the biodistribution and residency of 90Y labelled agents using the brehmsstrahlung imaging technique (b) the tumour response to various treatment modalities using a simplified scintigraphic method [Functional SPECT tumour volume (STV)]. Material and methods: 1) 19 patients with NETs were imaged with 111In-pentetreotide and 14 of them underwent treatment with 90Y-lanreotide. The rest underwent treatment with 90Y-SMT. All the patients were imaged 24 hours post-therapy. Brehmsstrahlung images obtained post therapies were used to assess the 90Y-lanreotide biodistribution in 14 patients and the 5 patients treated with 90Y-SMT, comparing them with 111In-pentetreotide. 2) In 42 patients with NETs a retrospective analysis was performed of the 111In-pentetreotide imaging and CT scan in patients treated with different therapies. A simplified scintigraphic method using 111In-pentetreotide SPECT liver imaging was used to monitor changes in tumour response and to determine how this correlates with CT scan and clinical response. Results: 1) 90Y-lanreotide and 90Y-SMT (with amino acids) have much lower uptake in the kidney (p 0.000 and 0.041 respectively) than 111In-pentetreotide. G Gnanasegaran MD 2 2) 22/42 patients had a good clinical response. A mean fall in total functional STV of 37% was seen in patients with symptomatic relief and a mean increase of 72 % was seen in patients with no symptomatic relief STV predicted the clinical outcome in 34 patients (81%) and CT predicted the outcome in 21 (50%) patients. Conclusion: There was a difference in biodistribution between 111In-pentetreotide and 90Y-lanreotide/ 90Y-SMT, especially in the

  1. Novel, dually radiolabeled peptides for simultaneous monitoring of enzymatic activity and protein targets

    SciTech Connect

    Efrem Mebrahtu, Suzanne Lapi

    2012-12-13

    This application investigated a novel imaging approach to develop methods to incorporate multiple radionuclides into a single peptide at chemoselective sites for simultaneous monitoring of cell-bound protein targets as well as specific enzymatic activity, both of which are associated with enhanced tumor growth and metastasis. This imaging construct was synthesized in such a manner so that the PET radionuclide will remain associated with the tumor cells and the SPECT radionuclide was cleaved from the imaging agent. Measurement of the PET agent only will yield information about the tumor marker density while measurement of the amount of co-localization and mismatch of the two radionuclides will yield information about the enzymatic activity. This coincident measuring technique using both PET and SPECT agents allows us to draw correlations involving the interactions of enzymes (cathepsin, serine-protease urokinase (uPA) and matrix metalloproteases) and other cellular proteins which play a role in cancer growth and metastasis. This technique will allow for studies in xenograft or genetic models of cancer in the same animal at the same time, thus eliminating problems that may occur when trying to invoke comparisons across animals or timepoints. By using radionuclide imaging as opposed to other imaging modalities, this technique has the potential to be translatable and can exploit the high specific activity probes which can be generated with radiotracers. The proof of principle test of this system investigated simultaneous monitoring of matrix metalloprotease (MMP) activity in the extracellular matrix (ECM) as well as density of integrins on the cell surface, both of which can serve as tumor markers. The outcomes/deliverables of this project were as follows: 1. Peptides were synthesized dually labeled at chemospecific sites with PET and SPECT agents. 2. Stability (intrinsic and to radiolysis) and specific activity of these labeled compounds were determined. 3. The

  2. Reversed-phase liquid chromatography of radiolabeled peptides using a C18 guard-PAK precolumn system

    SciTech Connect

    Carriere, P.D.; Bennett, H.P. )

    1989-03-01

    In order to avoid radioactive contamination of high-performance liquid chromatography columns and injectors, we have investigated the use of a Guard-PAK precolumn system for the chromatography of ({sup 125}I) labeled peptides. Two gonadotropin-releasing hormone analogs: (1) (D-Ala6-des-Gly10)-GnRH (GnRH-(Ala6)) and (2) (D-Ser(TBu)6-des-Gly10)-GnRH (GnRH-(Ser6)) and rat prolactin (r-PRL) were radiolabeled with {sup 125}I and subjected to reversed-phase liquid chromatography using a C18 Guard-PAK precolumn system. Major peak fractions of purified ({sup 125}I)GnRH-(Ala6), ({sup 125}I)GnRH-(Ser6), and ({sup 125}I)r-PRL eluted at 24%, 28%, and 55% acetonitrile, respectively. Purified ({sup 125}I)GnRH analogs showed specific high affinity binding to rat anterior pituitary gland membranes (specific activity: 1500-1700 Ci/mmol). Purified ({sup 125}I)r-PRL showed high affinity binding to r-PRL antibody by RIA (specific activity: 70-75 microCi/micrograms). This rapid and efficient chromatographic method should be useful in the separation of a wide range of radiolabeled protein and peptide molecules.

  3. F-18 Labeled Vasoactive Intestinal Peptide Analogue in the PET Imaging of Colon Carcinoma in Nude Mice

    PubMed Central

    Liu, Yuxia; Shen, Hua; Pang, Lifang; Yin, Duanzhi; Wang, Yongxian; Li, Shanqun; Shi, Hongcheng

    2013-01-01

    As large amount of vasoactive intestinal peptide (VIP) receptors are expressed in various tumors and VIP-related diseases, radiolabeled VIP provides a potential PET imaging agent for VIP receptor. However, structural modification of VIP is required before being radiolabeled and used for VIP receptor imaging due to its poor in vivo stability. As a VIP analogue, [R8, 15, 21, L17]-VIP exhibited improved stability and receptor specificity in preliminary studies. In this study, F-18 labeled [R8,15,21, L17]-VIP was produced with the radiochemical yield being as high as 33.6% ± 3% (decay-for-corrected, n = 5) achieved within 100 min, a specific activity of 255 GBq/μmol, and a radiochemical purity as high as 99% as characterized by radioactive HPLC, TLC, and SDS-Page radioautography. A biodistribution study in normal mice also demonstrated fast elimination of F-18 labeled [R8,15,21, L17]-VIP in the blood, liver, and gastrointestinal tracts. A further micro-PET imaging study in C26 colon carcinoma bearing mice confirmed the high tumor specificity, with the tumor/muscle radioactivity uptake ratio being as high as 3.03 at 60 min following injection, and no apparent radioactivity concentration in the intestinal tracts. In addition, blocking experiment and Western Blot test further confirmed its potential in PET imaging of VIP receptor-positive tumor. PMID:24459669

  4. Interim report on intrathoracic radiotherapy of human small-cell lung carcinoma in nude mice with Re-188-RC-160, a radiolabeled somatostatin analogue

    SciTech Connect

    Zamora, P.O. |; Bender, H.; Biersack, H.J.; Knapp, F.F. Jr.

    1995-07-01

    The purpose of this study was to evaluate the therapeutic efficacy of Re-188-RC-160 in experimental models of human small cell lung carcinomas which mimic the clinical presentation. In the experimental model, cells from the human small cell lung carcinoma cell line NCI-H69 cells were inoculated into the thoracic cavity of athymic mice and rats. Subsequently, the biodistribution of Re-188-RC-160 after injection into the pleural cavity, a radiolabeled somatostatin analogue, was monitored as was the effect on the subsequent growth of tumors. The results presented here, and which are a part of a larger series of studies, suggest that Re-188-RC-160 can be effectively used in this animal model to restrict the growth of small cell lung carcinoma in the thoracic cavity.

  5. Antimicrobial activity of antihypertensive food-derived peptides and selected alanine analogues.

    PubMed

    McClean, Stephen; Beggs, Louise B; Welch, Robert W

    2014-03-01

    This study evaluated four food-derived peptides with known antihypertensive activities for antimicrobial activity against pathogenic microorganisms, and assessed structure-function relationships using alanine analogues. The peptides (EVSLNSGYY, barley; PGTAVFK, soybean; TTMPLW, α-casein; VHLPP, α-zein) and the six alanine substitution peptides of PGTAVFK were synthesised, characterised and evaluated for antimicrobial activity using the bacteria, Escherichia coli, Staphylococcus aureus, and Micrococcus luteus and the yeast, Candida albicans. The peptides TTMPLW and PGTAVFK inhibited growth of all four microorganisms tested, with activities of a similar order of magnitude to ampicillin and ethanol controls. EVSLNSGYY inhibited the growth of the bacteria, but VHLPP showed no antimicrobial activity. The alanine analogue, PGAAVFK showed the highest overall antimicrobial activity and PGTAVFA showed no activity; overall, the activities of the analogues were consistent with their structures. Some peptides with antihypertensive activity also show antimicrobial activity, suggesting that food-derived peptides may exert beneficial effects via a number of mechanisms.

  6. Mapping of radiolabeled peptides derived from proteolysis of polypeptides bound to nitrocellulose after Western blotting

    SciTech Connect

    Carrey, E.A.; Hardie, D.G.

    1986-11-01

    Sections of nitrocellulose containing bound /sup 32/P-labeled polypeptides were excised from Western blots and exhaustively digested by trypsin in order to analyze the distribution of phosphorylation sites between the products of limited proteolysis of the multifunctional protein CAD. Using the criterion of analytical isoelectric focusing, the /sup 32/P-peptides obtained by this method were found to be similar, although not identical, to peptides obtained by a more conventional digestion of trichloroacetic acid precipitates. Digestion on Western blots is more straightforward than electrophoretic elution of individual gel slices, gives better recoveries than direct digestion of gel slices, and is particularly suitable for peptide mapping of small peptides which bind to nitrocellulose but would diffuse out of polyacrylamide gels during the commonly used fixing and staining procedures.

  7. Radiolabeled Cyclic RGD Peptides as Radiotracers for Imaging Tumors and Thrombosis by SPECT

    PubMed Central

    Zhou, Yang; Chakraborty, Sudipta; Liu, Shuang

    2011-01-01

    The integrin family is a group of transmembrane glycoprotein comprised of 19 α- and 8 β-subunits that are expressed in 25 different α/β heterodimeric combinations on the cell surface. Integrins play critical roles in many physiological processes, including cell attachment, proliferation, bone remodeling, and wound healing. Integrins also contribute to pathological events such as thrombosis, atherosclerosis, tumor invasion, angiogenesis and metastasis, infection by pathogenic microorganisms, and immune dysfunction. Among 25 members of the integrin family, the αvβ3 is studied most extensively for its role of tumor growth, progression and angiogenesis. In contrast, the αIIbβ3 is expressed exclusively on platelets, facilitates the intercellular bidirectional signaling (“inside-out” and “outside-in”) and allows the aggregation of platelets during vascular injury. The αIIbβ3 plays an important role in thrombosis by its activation and binding to fibrinogen especially in arterial thrombosis due to the high blood flow rate. In the resting state, the αIIbβ3 on platelets does not bind to fibrinogen; on activation, the conformation of platelet is altered and the binding sites of αIIbβ3 are exposed for fibrinogen to crosslink platelets. Over the last two decades, integrins have been proposed as the molecular targets for diagnosis and therapy of cancer, thrombosis and other diseases. Several excellent review articles have appeared recently to cover a broad range of topics related to the integrin-targeted radiotracers and their nuclear medicine applications in tumor imaging by single photon emission computed tomography (SPECT) or a positron-emitting radionuclide for positron emission tomography (PET). This review will focus on recent developments of αvβ3-targeted radiotracers for imaging tumors and the use of αIIbβ3-targeted radiotracers for thrombosis imaging, and discuss different approaches to maximize the targeting capability of cyclic RGD peptides

  8. Radiolabeling of a cyclic RGD (cyclo Arg-Gly-Asp-d-Tyr-Lys) peptide using sodium hypochlorite as an oxidizing agent.

    PubMed

    Doll, Stephanie; Woolum, Karen; Kumar, Krishan

    2016-09-01

    A simple and rapid nonradioactive iodide labeling/radiolabeling method for peptides, using an inexpensive oxidizing agent such as sodium hypochlorite and a cyclic peptide, cRGDyK (cyclo Arg-Gly-Asp-d-Tyr-Lys), was developed in this work. Labeling reaction was optimized by conducting experiments under variable ratios of the reagents, the reaction times, and the pH. The study demonstrated that radiolabeling of the cyclic peptide was fast and pH independent. Monoiodinated and di-iodinated cRGDyK were formed under all conditions and varied with the ratio of the reagents and the reaction time. Total percent of the iodinated cRGDyK (monoiodinated and di-iodinated cRGDyK) varied between 44 and 100 depending on the reaction conditions. Excess cyclic peptide over equal molar ratio of sodium iodide and sodium hypochlorite yielded in predominant amounts of monoiodinated cRGDyK, ie, >60% under 2:1:1 ratio and ~88% under 5:1:1 ratio of cRGDyK:sodium iodide:sodium hypochlorite.

  9. Investigation of Serine-Proteinase-Catalyzed Peptide Splicing in Analogues of Sunflower Trypsin Inhibitor 1 (SFTI-1).

    PubMed

    Karna, Natalia; Łęgowska, Anna; Malicki, Stanisław; Dębowski, Dawid; Golik, Przemysław; Gitlin, Agata; Grudnik, Przemysław; Wladyka, Benedykt; Brzozowski, Krzysztof; Dubin, Grzegorz; Rolka, Krzysztof

    2015-09-21

    Serine-proteinase-catalyzed peptide splicing was demonstrated in analogues of the trypsin inhibitor SFTI-1: both single peptides and two-peptide chains (C- and N-terminal peptide chains linked by a disulfide bridge). In the second series, peptide splicing with catalytic amount of proteinase was observed only when formation of acyl-enzyme intermediate was preceded by hydrolysis of the substrate Lys-Ser peptide bond. Here we demonstrate that with an equimolar amount of the proteinase, splicing occurs in all the two-peptide-chain analogues. This conclusion was supported by high resolution crystal structures of selected analogues in complex with trypsin. We showed that the process followed a direct transpeptidation mechanism. Thus, the acyl-enzyme intermediate was formed and was immediately used for a new peptide bond formation; products associated with the hydrolysis of the acyl-enzyme were not observed. The peptide splicing was sequence- not structure-specific.

  10. Design of novel analogues of short antimicrobial peptide anoplin with improved antimicrobial activity.

    PubMed

    Wang, Yang; Chen, Jianbo; Zheng, Xin; Yang, Xiaoli; Ma, Panpan; Cai, Ying; Zhang, Bangzhi; Chen, Yuan

    2014-12-01

    Currently, novel antibiotics are urgently required to combat the emergence of drug-resistant bacteria. Antimicrobial peptides with membrane-lytic mechanism of action have attracted considerable interest. Anoplin, a natural α-helical amphiphilic antimicrobial peptide, is an ideal research template because of its short sequence. In this study, we designed and synthesized a group of analogues of anoplin. Among these analogues, anoplin-4 composed of D-amino acids displayed the highest antimicrobial activity due to increased charge, hydrophobicity and amphiphilicity. Gratifyingly, anoplin-4 showed low toxicity to host cells, indicating high bacterial selectivity. Furthermore, the mortality rate of mice infected with Escherichia coli was significantly reduced by anoplin-4 treatment relative to anoplin. In conclusion, anoplin-4 is a novel anoplin analogue with high antimicrobial activity and enzymatic stability, which may represent a potent agent for the treatment of infection.

  11. Radiolabeling and evaluation of 64Cu-DOTA-F56 peptide targeting vascular endothelial growth factor receptor 1 in the molecular imaging of gastric cancer

    PubMed Central

    Zhu, Hua; Zhao, Chuanke; Liu, Fei; Wang, Lixin; Feng, Junnan; Zhou, Zheng; Qu, Like; Shou, Chengchao; Yang, Zhi

    2015-01-01

    Noninvasive imaging of vascular endothelial growth factor receptor 1 (VEGFR1) remains a great challenge in early diagnosis of gastric cancer. Here we reported the synthesis, radiolabeling, and evaluation of a novel 64Cu-radiolabeled peptide for noninvasive positron emission tomography (PET) imaging of VEGFR1 positive gastric cancer. The binding of modified peptide WHSDMEWWYLLG (termed as F56) to VEGER-1 expressed in gastric cancer cell BCG823 has been confirmed by immune-fluorescence overlap. DOTA-F56 was designed and prepared by solid-phase synthesis and folded in vitro. 64Cu-DOTA-F56 was synthesized in high radiochemical yield and high specific activity (S.A. up to 255.6 GBq/mmol). It has excellent in vitro stability. Micro-PET imaging of 64Cu-DOTA-F56 identifies tumor in BCG823 tumor-bearing mice, while that of 18F-FDG does not. Immunohistochemical analysis of excised BCG823 xenograft showed colocalization between the PET images and the staining of VEGFR1. These results demonstrated that 64Cu-DOTA-F56 peptide has potential as a noninvasive imaging agent in VEGFR1 positive tumors. PMID:26807312

  12. Secondary structure propensity and chirality of the amyloidophilic peptide p5 and its analogues impacts ligand binding - In vitro characterization

    DOE PAGES

    Wall, Jonathan S.; Williams, Angela; Wooliver, Craig; ...

    2016-08-11

    Here, polybasic helical peptides, such as peptide p5, bind human amyloid extracts and synthetic amyloid fibrils. When radio labeled, peptide p5 has been shown to specifically bind amyloid in vivo thereby allowing imaging of the disease. Structural requirements for heparin and amyloid binding have been studied using analogues of p5 that modify helicity and chirality.

  13. New trends in the development of opioid peptide analogues as advanced remedies for pain relief.

    PubMed

    Gentilucci, Luca

    2004-01-01

    The search for new peptides to be used as analgesics in place of morphine has been mainly directed to develop peptide analogues or peptidomimetics having higher biological stability and receptor selectivity. Indeed, most of the alkaloid opioid counterindications are due to the scarce stability and the contemporary activation of different receptor types. However, the development of several extremely stable and selective peptide ligands for the different opioid receptors, and the recent discovery of the micro-receptor selective endomorphins, rendered this search less fundamental. In recent years, other opioid peptide properties have been investigated in the search for new pharmacological tools. The utility of a drug depends on its ability to reach appropriate receptors at the target tissue and to remain metabolically stable in order to produce the desired effect. This review deals with the recent investigations on peptide bioavailability, in particular barrier penetration and resistance against enzymatic degradation; with the development of peptides having activity at different receptors; with chimeric peptides, with propeptides, and with non-conventional peptides, lacking basic pharmacophoric features.

  14. Synthesis and biological activities of some pseudo-peptide analogues of tetragastrin: the importance of the peptide backbone.

    PubMed

    Martinez, J; Bali, J P; Rodriguez, M; Castro, B; Magous, R; Laur, J; Lignon, M F

    1985-12-01

    Pseudo-peptide analogues of the C-terminal tetrapeptide of gastrin, in which a peptide bond has been replaced by a CH2-NH bond, i.e. (tert-butyloxycarbonyl)-L-tryptophyl-psi (CH2-NH)-L-leucyl-L-aspartyl-L-phenylalanine amide (8), (tert-butyloxycarbonyl)-L-tryptophyl-L-leucyl-psi (CH2-NH)-L-aspartyl-L-phenylalanine amide (13), (tert-butyloxycarbonyl)-L-tryptophyl-L-leucyl-L-aspartyl-psi (CH2NH)-L-phenylalanine amide (20), were synthesized. The pseudo-peptides 8 and 13 were shown to have the same affinity as (tert-butyloxycarbonyl)-L-tryptophyl-L-leucyl-L-aspartyl-L-phenylalanine amide (21) for the gastrin receptor on isolated mucosal cells. The pseudo-peptide 20 exhibited lower affinity (IC50 congruent to 10(-5) M). The biological activity of these pseudo-peptides was studied on acid secretion in the anesthetized rat. Compound 8 stimulated acid secretion, identically with that of 21. Compound 13 did not exhibit any agonist activity but was able to antagonize the action of gastrin (ED50 = 0.3 mg/kg). Compound 20 did not show any agonist activity but was able to inhibit gastrin-induced acid secretion, with lower potency (ED50 = 15 mg/kg). The importance of the peptide bonds in the mode of action of gastrin is discussed, and a hypothetical approach of the mechanism of action is presented.

  15. The Structure-Activity Relationship of Glycosaminoglycans and Their Analogues with β-Amyloid Peptide.

    PubMed

    Zhou, Xiang; Jin, Lan

    2016-01-01

    Alzheimer's disease (AD) is a serious neurodegenerative disorder. β-amyloid peptide (Aβ) aggregation is believed to be the major cause of the disease. The process of Aβ aggregation can be enhanced by sulfated glycosaminoglycans. However, cell experiments have shown that sulfated glycosaminoglycan oligosaccharides or analogues may have significant neuroprotective properties and could inhibit the aggregation by competitive inhibition. The length and species of oligosaccharides or analogues can inhibit the toxicity of Aβ by inducing conformational changes of proteins in different manners. This review presents the conformational changes of Aβ in the presence of glycosaminoglycan, glycosaminoglycan oligosaccharides and analogues. The review might be helpful to comprehend the mechanism of β-amyloid fibrillations and the aggregation process.

  16. Novel alpha-melanocyte stimulating hormone peptide analogues with high candidacidal activity.

    PubMed

    Grieco, Paolo; Rossi, Claudia; Colombo, Gualtiero; Gatti, Stefano; Novellino, Ettore; Lipton, James M; Catania, Anna

    2003-02-27

    alpha-Melanocyte stimulating hormone (alpha-MSH) is an endogenous linear tridecapeptide with potent antiinflammatory effects. We recently demonstrated that alpha-MSH and its C-terminal sequence Lys-Pro-Val (alpha-MSH (11-13)) have antimicrobial effects against two major and representative pathogens: Staphylococcus aureus and Candida albicans. In an attempt to improve the candidacidal activity of alpha-MSH and to better understand the peptide structure-antifungal activity relations, we designed and synthesized novel peptide analogues. Because previous data suggested that antimicrobial effects of alpha-MSH were receptor-mediated, we chose to focus on the sequence alpha-MSH (6-13), which contains the invariant core sequence His-Phe-Arg-Trp (6-9) that is important for binding to the known melanocortin receptors and also contains the sequence Lys-Pro-Val (11-13) that is known to be important for antimicrobial activity. In this structure-activity study, we discovered several compounds that have greater candidacidal activity than alpha-MSH. The peptide [d-Nal-7,Phe-12]-alpha-MSH (6-13) was the most potent of the analogues tested. The present results are very encouraging because they show the great potential of these peptides as a truly novel class of candidacidal compounds.

  17. Rapid analysis of protein farnesyltransferase substrate specificity using peptide libraries and isoprenoid diphosphate analogues.

    PubMed

    Wang, Yen-Chih; Dozier, Jonathan K; Beese, Lorena S; Distefano, Mark D

    2014-08-15

    Protein farnesytransferase (PFTase) catalyzes the farnesylation of proteins with a carboxy-terminal tetrapeptide sequence denoted as a Ca1a2X box. To explore the specificity of this enzyme, an important therapeutic target, solid-phase peptide synthesis in concert with a peptide inversion strategy was used to prepare two libraries, each containing 380 peptides. The libraries were screened using an alkyne-containing isoprenoid analogue followed by click chemistry with biotin azide and subsequent visualization with streptavidin-AP. Screening of the CVa2X and CCa2X libraries with Rattus norvegicus PFTase revealed reaction by many known recognition sequences as well as numerous unknown ones. Some of the latter occur in the genomes of bacteria and viruses and may be important for pathogenesis, suggesting new targets for therapeutic intervention. Screening of the CVa2X library with alkyne-functionalized isoprenoid substrates showed that those prepared from C10 or C15 precursors gave similar results, whereas the analogue synthesized from a C5 unit gave a different pattern of reactivity. Lastly, the substrate specificities of PFTases from three organisms (R. norvegicus, Saccharomyces cerevisiae, and Candida albicans) were compared using CVa2X libraries. R. norvegicus PFTase was found to share more peptide substrates with S. cerevisiae PFTase than with C. albicans PFTase. In general, this method is a highly efficient strategy for rapidly probing the specificity of this important enzyme.

  18. PACE4-based molecular targeting of prostate cancer using an engineered ⁶⁴Cu-radiolabeled peptide inhibitor.

    PubMed

    Couture, Frédéric; Levesque, Christine; Dumulon-Perreault, Véronique; Ait-Mohand, Samia; D'Anjou, François; Day, Robert; Guérin, Brigitte

    2014-08-01

    The potential of PACE4 as a pharmacological target in prostate cancer has been demonstrated as this proprotein convertase is strongly overexpressed in human prostate cancer tissues and its inhibition, using molecular or pharmacological approaches, results in reduced cell proliferation and tumor progression in mouse tumor xenograft models. We developed a PACE4 high-affinity peptide inhibitor, namely, the multi-leucine (ML), and sought to determine whether this peptide could be exploited for the targeting of prostate cancer for diagnostic or molecular imaging purposes. We conjugated a bifunctional chelator 1,4,7-triazacyclononane-1,4,7- triacetic acid (NOTA) to the ML peptide for copper-64 ((64)Cu) labeling and positron emission tomography (PET)- based prostate cancer detection. Enzyme kinetic assays against recombinant PACE4 showed that the NOTA-modified ML peptide displays identical inhibitory properties compared to the unmodified peptide. In vivo biodistribution of the (64)Cu/NOTA-ML peptide evaluated in athymic nude mice bearing xenografts of two human prostate carcinoma cell lines showed a rapid and high uptake in PACE4-expressing LNCaP tumor at an early time point and in PACE4-rich organs. Co-injection of unlabeled peptide confirmed that tumor uptake was target-specific. PACE4-negative tumors displayed no tracer uptake 15 minutes after injection, while the kidneys, demonstrated high uptake due to rapid renal clearance of the peptide. The present study supports the feasibility of using a (64)Cu/NOTA-ML peptide for PACE4-targeted prostate cancer detection and PACE4 status determination by PET imaging but also provides evidence that ML inhibitor-based drugs would readily reach tumor sites under in vivo conditions for pharmacological intervention or targeted radiation therapy.

  19. An analogue peptide from the Cancer/Testis antigen PASD1 induces CD8+ T cell responses against naturally processed peptide.

    PubMed

    Hardwick, Nicola; Buchan, Sarah; Ingram, Wendy; Khan, Ghazala; Vittes, Gisella; Rice, Jason; Pulford, Karen; Mufti, Ghulam; Stevenson, Freda; Guinn, Barbara-ann

    2013-01-01

    We have previously identified the novel Cancer/Testis antigen PASD1 by immunoscreening a testis library with pooled acute myeloid leukemia (AML) patient sera. To develop a cytotoxic T lymphocyte (CTL)-inducing vaccine, we have now investigated the carboxy-terminal region, known to contain serological determinants, for MHC class I (HLA-A⋆0201)-binding peptides. Algorithm-selected natural peptides failed to show detectable HLA-A⋆0201 binding in T2 assays. However, anchor-modified analogue peptides showed enhanced binding, with decreased off-rates. Analogue peptide-loaded antigen-presenting cells (APCs) induced IFN-γ production by T cells from normal donors and patients. In addition, peptide-specific T cells could be expanded from cancer patients by stimulation with the PASD1 analogue peptide Pa14. For clinical application, a DNA fusion gene vaccine encoding Pa14 was designed and tested in "humanized" mice. Splenocytes from vaccinated mice showed in vitro cytotoxicity against tumour cells, either exogenously loaded with the corresponding wild-type peptide (Pw8) or expressing endogenously processed PASD1 protein. We show for the first time that a DNA vaccine encoding an altered PASD1 epitope can induce CTLs to target the natural peptide expressed by human tumour cells.

  20. [18F]- and [11C]-Labeled N-benzyl-isatin sulfonamide analogues as PET tracers for apoptosis: synthesis, radiolabeling mechanism, and in vivo imaging of apoptosis in Fas-treated mice

    PubMed Central

    Zhou, Dong; Chu, Wenhua; Chen, Delphine L.; Wang, Qi; Reichert, David E.; Rothfuss, Justin; D'Avignon, Andre; Welch, Michael J.; Mach, Robert H.

    2011-01-01

    Summary The radiolabeled isatin sulfonamide caspase-3 inhibitor, [18F]2 (WC-II-89), is a potential PET radiotracer for noninvasive imaging of apoptosis. The radiolabeling mechanism was studied by 13C NMR, ESI/MS, and computational calculations. It was found that the high electrophilicity of the C3 carbonyl group in the isatin ring, which served as a trap for [18F]fluoride, was responsible for the failure of the radiolabeling via nucleophilic substitution of the mesylate group in 7a by [18F]fluoride. Once treated with a strong base, 7a opened the isatin ring completely to form an isatinate intermediate 16, which lost the ability to trap [18F]fluoride, thereby allowing the displacement of the mesylate group to afford the 18F-labeled isatinate 17. [18F]17 can be converted to isatin [18F]2 efficiently under acidic conditions. The ring-opening and re-closure of the isatin ring under basic and acidic conditions were confirmed by reversed phase HPLC analysis, ESI/MS and 13C NMR studies. Computational studies of model compounds also support the above proposed mechanism. Similarly, the ring-opening and re-closure method was used successfully in the synthesis of the 11C labeled isatin sulfonamide analogue [11C]4 (WC-98). A microPET imaging study using [11C]4 in the Fas liver apoptosis model demonstrated retained activity in the target organ (liver) of the treated mice. Increased caspase-3 activation in the liver was verified by the fluorometric caspase-3 enzyme assay. Therefore, this study provides a useful method for radio-synthesis of isatin derivative radiotracers for PET and SPECT studies, and [11C]4 is a potential PET radiotracer for noninvasive imaging of apoptosis. PMID:19300818

  1. Structural and Functional Characterization of a Multifunctional Alanine-Rich Peptide Analogue from Pleuronectes americanus

    PubMed Central

    Migliolo, Ludovico; Silva, Osmar N.; Silva, Paula A.; Costa, Maysa P.; Costa, Carolina R.; Nolasco, Diego O.; Barbosa, João A. R. G.; Silva, Maria R. R.; Bemquerer, Marcelo P.; Lima, Lidia M. P.; Romanos, Maria T. V.; Freitas, Sonia M.; Magalhães, Beatriz S.; Franco, Octavio L.

    2012-01-01

    Recently, defense peptides that are able to act against several targets have been characterized. The present work focuses on structural and functional evaluation of the peptide analogue Pa-MAP, previously isolated as an antifreeze peptide from Pleuronectes americanus. Pa-MAP showed activities against different targets such as tumoral cells in culture (CACO-2, MCF-7 and HCT-116), bacteria (Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 25923), viruses (HSV-1 and HSV-2) and fungi (Candida parapsilosis ATCC 22019, Trichophyton mentagrophytes (28d&E) and T. rubrum (327)). This peptide did not show toxicity against mammalian cells such as erythrocytes, Vero and RAW 264.7 cells. Molecular mechanism of action was related to hydrophobic residues, since only the terminal amino group is charged at pH 7 as confirmed by potentiometric titration. In order to shed some light on its structure-function relations, in vitro and in silico assays were carried out using circular dichroism and molecular dynamics. Furthermore, Pa-MAP showed partial unfolding of the peptide changes in a wide pH (3 to 11) and temperature (25 to 95°C) ranges, although it might not reach complete unfolding at 95°C, suggesting a high conformational stability. This peptide also showed a conformational transition with a partial α-helical fold in water and a full α-helical core in SDS and TFE environments. These results were corroborated by spectral data measured at 222 nm and by 50 ns dynamic simulation. In conclusion, data reported here show that Pa-MAP is a potential candidate for drug design against pathogenic microorganisms due to its structural stability and wide activity against a range of targets. PMID:23056574

  2. Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide.

    PubMed

    Lau, Jesper; Bloch, Paw; Schäffer, Lauge; Pettersson, Ingrid; Spetzler, Jane; Kofoed, Jacob; Madsen, Kjeld; Knudsen, Lotte Bjerre; McGuire, James; Steensgaard, Dorte Bjerre; Strauss, Holger Martin; Gram, Dorte X; Knudsen, Sanne Møller; Nielsen, Flemming Seier; Thygesen, Peter; Reedtz-Runge, Steffen; Kruse, Thomas

    2015-09-24

    Liraglutide is an acylated glucagon-like peptide-1 (GLP-1) analogue that binds to serum albumin in vivo and is approved for once-daily treatment of diabetes as well as obesity. The aim of the present studies was to design a once weekly GLP-1 analogue by increasing albumin affinity and secure full stability against metabolic degradation. The fatty acid moiety and the linking chemistry to GLP-1 were the key features to secure high albumin affinity and GLP-1 receptor (GLP-1R) potency and in obtaining a prolonged exposure and action of the GLP-1 analogue. Semaglutide was selected as the optimal once weekly candidate. Semaglutide has two amino acid substitutions compared to human GLP-1 (Aib(8), Arg(34)) and is derivatized at lysine 26. The GLP-1R affinity of semaglutide (0.38 ± 0.06 nM) was three-fold decreased compared to liraglutide, whereas the albumin affinity was increased. The plasma half-life was 46.1 h in mini-pigs following i.v. administration, and semaglutide has an MRT of 63.6 h after s.c. dosing to mini-pigs. Semaglutide is currently in phase 3 clinical testing.

  3. Structure of synthetic peptide analogues of an eggshell protein of Schistosoma mansoni.

    PubMed Central

    Middaugh, C. R.; Thomson, J. A.; Burke, C. J.; Mach, H.; Naylor, A. M.; Bogusky, M. J.; Ryan, J. A.; Pitzenberger, S. M.; Ji, H.; Cordingley, J. S.

    1993-01-01

    The peptide (Gly-L-Tyr-L-Asp-L-Lys-L-Tyr)6, referred to as F4-6, was synthesized as a model for a schistosome eggshell protein in which the Gly-Tyr-Asp-Lys-Tyr consensus sequence is repeated over 40 times. Analysis by CD, Fourier transform infrared spectroscopy, potentiometric and spectrophotomertric titrations, NMR, and molecular modeling suggests that F4-6 forms some type of left-handed structure. A likely possibility appears to be a left-handed alpha-helix stabilized by Lysi-Aspi +4 salt bridges and possibly Aspi-Tyri +4 hydrogen bonding and Tyr-Tyr interactions. Spectroscopic studies of a number of F4-6 analogues support this conclusion. For example, substitution of D-Ala for Gly produces a peptide with enhanced left-handed helical spectral characteristics, whereas an L-Ala substitution results in a peptide with minimal structure. These studies suggest that the F4 protein from Schistosoma mansoni may be the first example of a naturally occurring protein devoid of proline and carbohydrate that forms a left-handed helix composed of L-amino acids, although alternative forms of other left-handed structures have yet to be rigorously excluded. PMID:8318895

  4. Molecular dynamics simulations of urea and thermal-induced denaturation of S-peptide analogue.

    PubMed

    Zhang, Z; Zhu, Y; Shi, Y

    2001-02-15

    Molecular dynamics simulations of the S-peptide analogue AETAAAKFLREHMDS in water at 278 and 358 K, and in 8 M urea at 278 K were performed. The results show agreement with experiments. The helix is stable at low temperature (278 K), while at 358 K, unfolding is observed. The effects of urea on protein stability have been studied. The data support a model in which urea denatures proteins by: (1) diminishing the hydrophobic effect by displacing water molecules from the solvent shell around nonpolar groups; and (2) binding directly to amide units (NH and CO groups) via hydrogen bonds. The results of cluster analysis and essential dynamics analysis suggest that the mechanism of urea and thermal-induced denaturation may not be the same.

  5. Secondary structure propensity and chirality of the amyloidophilic peptide p5 and its analogues impacts ligand binding - In vitro characterization

    SciTech Connect

    Wall, Jonathan S.; Williams, Angela; Wooliver, Craig; Martin, Emily B.; Cheng, Xiaolin; Heidel, R. Eric; Kennel, Stephen J.

    2016-08-11

    Here, polybasic helical peptides, such as peptide p5, bind human amyloid extracts and synthetic amyloid fibrils. When radio labeled, peptide p5 has been shown to specifically bind amyloid in vivo thereby allowing imaging of the disease. Structural requirements for heparin and amyloid binding have been studied using analogues of p5 that modify helicity and chirality.

  6. Binding affinities of amino acid analogues at the charged aqueous titania interface: implications for titania-binding peptides.

    PubMed

    Sultan, Anas M; Hughes, Zak E; Walsh, Tiffany R

    2014-11-11

    Despite the extensive utilization of biomolecule-titania interfaces, biomolecular recognition and interactions at the aqueous titania interface remain far from being fully understood. Here, atomistic molecular dynamics simulations, in partnership with metadynamics, are used to calculate the free energy of adsorption of different amino acid side chain analogues at the negatively-charged aqueous rutile TiO2 (110) interface, under conditions corresponding with neutral pH. Our calculations predict that charged amino acid analogues have a relatively high affinity to the titania surface, with the arginine analogue predicted to be the strongest binder. Interactions between uncharged amino acid analogues and titania are found to be repulsive or weak at best. All of the residues that bound to the negatively-charged interface show a relatively stronger adsorption compared with the charge-neutral interface, including the negatively-charged analogue. Of the analogues that are found to bind to the titania surface, the rank ordering of the binding affinities is predicted to be "arginine" > "lysine" ≈ aspartic acid > "serine". This is the same ordering as was found previously for the charge-neutral aqueous titania interface. Our results show very good agreement with available experimental data and can provide a baseline for the interpretation of peptide-TiO2 adsorption data.

  7. Synthesis of a-factor peptide from Saccharomyces cerevisiae and photoactive analogues via Fmoc solid phase methodology.

    PubMed

    Mullen, Daniel G; Kyro, Kelly; Hauser, Melinda; Gustavsson, Martin; Veglia, Gianluigi; Becker, Jeffery M; Naider, Fred; Distefano, Mark D

    2011-01-01

    a-Factor from Saccharomyces cerevisiae is a farnesylated dodecapeptide involved in mating. The molecule binds to a G-protein coupled receptor and hence serves as a simple system for studying the interactions between prenylated molecules and their cognate receptors. Here, we describe the preparation of a-factor and two photoactive analogues via Fmoc solid-phase peptide synthesis using hydrazinobenzoyl AM NovaGel™ resin; the structure of the synthetic a-factor was confirmed by MS-MS analysis and NMR; the structures of the analogues were confirmed by MS-MS analysis. Using a yeast growth arrest assay, the analogues were found to have activity comparable to a-factor itself.

  8. Synthesis of a-factor peptide from Saccharomyces cerevisiae and photoactive analogues via Fmoc solid phase methodology

    PubMed Central

    Mullen, Daniel G.; Kyro, Kelly; Hauser, Melinda; Gustavsson, Martin; Veglia, Gianluigi; Becker, Jeffery M.; Naider, Fred; Distefano, Mark D.

    2010-01-01

    a-Factor from S. cerevisiae is a farnesylated dodecapeptide involved in mating. The molecule binds to a G-protein coupled receptor and hence serves as a simple system for studying the interactions between prenylated molecules and their cognate receptors. Here, we describe the preparation of a-factor and two photoactive analogues via Fmoc solid-phase peptide synthesis using hydrazinobenzoyl AM NovaGel™ resin; the structure of the synthetic a-factor was confirmed by MS-MS analysis and NMR; the structures of the analogues were confirmed by MS-MS analysis. Using a yeast growth arrest assay, the analogues were found to have activity comparable to a-factor itself. PMID:21134758

  9. Design, synthesis and biological evaluation of novel peptide MC2 analogues from Momordica charantia as potential anti-diabetic agents.

    PubMed

    Yang, Baowei; Li, Xue; Zhang, Chenyu; Yan, Sijia; Wei, Wei; Wang, Xuekun; Deng, Xin; Qian, Hai; Lin, Haiyan; Huang, Wenlong

    2015-04-21

    Three series of Momordica charantia (MC)2 analogues were designed, synthesized and evaluated for their anti-hyperglycaemic effects. Alanine scanning focusing on the peptide MC2 indicated the importance of the residues proline (Pro)(3), serine (Ser)(6), isoleucine (Ile)(7) and Ser(10) for anti-hyperglycaemic effects. Among the first series of MC2 analogues, peptide I-4 exhibited a better anti-hyperglycaemic effect and was chosen for further modification. A further two series of conformationally constrained analogues were designed by scanning the residues Pro(3), Ser(6), Ile(7), and Ser(10) with an i - (i + 2) lactam bridge consisting of a glutamic acid-Xaa-lysine (Glu-Xaa-Lys) scaffold and a diproline fragment. By screening in normal mice and mice with diabetes mellitus, peptides II-1, II-2 and III-3 showed a significant improvement in anti-hyperglycaemic and anti-oxidative activities compared with I-4. These data suggest that II-1, II-2 and III-3 could be candidates for future treatment of diabetes mellitus.

  10. Sulfonation of Tyrosine as a Method to Improve Biodistribution of Peptide-Based Radiotracers: Novel (18)F-Labelled Cyclic RGD Analogues.

    PubMed

    Haskali, Mohammad Baqir; Denoyer, Delphine; Noonan, Wayne; Cullinane, Carleen; Rangger, Christine; Pouliot, Normand; Haubner, Roland; Roselt, Peter D; Hicks, Rodney J; Hutton, Craig A

    2017-02-13

    The labeling of peptides with positron emitting radionuclides has long held the promise of a wide range of PET agents possessing high affinity and selectivity. Not surprisingly, controlling the biodistribution of these agents has proven to be a major challenge in their successful application. Modification of peptide hydrophilicity in order to increase renal clearance has been a common endeavor to improve overall biodistribution. Herein, we examine the effect of site-specific sulfonation of tyrosine moieties in cyclic(RGDyK) peptides as a means to enhance their hydrophilicity and improve their biodistribution. The novel sulfonated cyclic(RGDyK) peptides were conjugated directly to 4-nitrophenyl 2-[18F]fluoropropionate and the biodistribution of the radiolabeled peptides was compared with that of their non-sulfonated, clinically relevant counterparts, [18F]GalactoRGD and [18F]FPPRGD2. Site-specific sulfonation of the tyrosine residues was shown to increase hydrophilicity and improve biodistribution of the RGD peptides, despite contributing just 79 Da towards the MW, compared with 189 Da for both the 'Galacto' and mini-PEG moieties, suggesting this may be a broadly applicable approach to enhancing biodistribution of radiolabelled peptides.

  11. Expression of neuropeptide hormone receptors in human adrenal tumors and cell lines: antiproliferative effects of peptide analogues.

    PubMed

    Ziegler, C G; Brown, J W; Schally, A V; Erler, A; Gebauer, L; Treszl, A; Young, L; Fishman, L M; Engel, J B; Willenberg, H S; Petersenn, S; Eisenhofer, G; Ehrhart-Bornstein, M; Bornstein, S R

    2009-09-15

    Peptide analogues targeting various neuropeptide receptors have been used effectively in cancer therapy. A hallmark of adrenocortical tumor formation is the aberrant expression of peptide receptors relating to uncontrolled cell proliferation and hormone overproduction. Our microarray results have also demonstrated a differential expression of neuropeptide hormone receptors in tumor subtypes of human pheochromocytoma. In light of these findings, we performed a comprehensive analysis of relevant receptors in both human adrenomedullary and adrenocortical tumors and tested the antiproliferative effects of peptide analogues targeting these receptors. Specifically, we examined the receptor expression of somatostatin-type-2 receptor, growth hormone-releasing hormone (GHRH) receptor or GHRH receptor splice variant-1 (SV-1) and luteinizing hormone-releasing hormone (LHRH) receptor at the mRNA and protein levels in normal human adrenal tissues, adrenocortical and adrenomedullary tumors, and cell lines. Cytotoxic derivatives of somatostatin AN-238 and, to a lesser extent, AN-162, reduced cell numbers of uninduced and NGF-induced adrenomedullary pheochromocytoma cells and adrenocortical cancer cells. Both the splice variant of GHRH receptor SV-1 and the LHRH receptor were also expressed in adrenocortical cancer cell lines but not in the pheochromocytoma cell line. The GHRH receptor antagonist MZ-4-71 and LHRH antagonist Cetrorelix both significantly reduced cell growth in the adrenocortical cancer cell line. In conclusion, the expression of receptors for somatostatin, GHRH, and LHRH in the normal human adrenal and in adrenal tumors, combined with the growth-inhibitory effects of the antitumor peptide analogues, may make possible improved treatment approaches to adrenal tumors.

  12. Molecular docking and 3D-QSAR studies on gag peptide analogue inhibitors interacting with human cyclophilin A.

    PubMed

    Cui, Meng; Huang, Xiaoqin; Luo, Xiaomin; Briggs, James M; Ji, Ruyun; Chen, Kaixian; Shen, Jianhua; Jiang, Hualiang

    2002-11-21

    The interaction of a series gag peptide analogues with human cyclophilin A (hCypA) have been studied employing molecular docking and 3D-QSAR approaches. The Lamarckian Genetic Algorithm (LGA) and divide-and-conquer methods were applied to locate the binding orientations and conformations of the inhibitors interacting with hCypA. Good correlations between the calculated interaction free energies and experimental inhibitory activities suggest that the binding conformations of these inhibitors are reasonable. A novel interaction model was identified for inhibitors 11, 15, and 17 whose N-termini were modified by addition of the deaminovaline (Dav) group and the C-termini of 15 and 17 were modified by addition of a benzyl group. Accordingly, two new binding sites (sites A and D in Figure 1) were revealed, which show a strong correlation with inhibitor potency and thus can be used as a starting point for new inhibitor design. In addition, two predictive 3D-QSAR models were obtained by CoMFA and CoMSIA analyses based on the binding conformations derived from the molecular docking calculations. The reasonable r(cross)(2) (cross-validated) values 0.738 and 0.762 were obtained for CoMFA and CoMSIA models, respectively. The predictive ability of these models was validated by four peptide analogues test set. The CoMFA and CoMSIA field distributions are in general agreement with the structural characteristics of the binding groove of hCypA. This indicates the reasonableness of the binding model of the inhibitors with hCypA. Considering all these results together with the valuable clues of binding from references published recently, reasonable pharmacophore elements have been suggested, demonstrating that the 3D-QSAR models about peptide analogue inhibitors are expected to be further employed in predicting activities of the novel compounds for inhibiting hCypA.

  13. Structure-Activity Relationship Studies of Amino Acid Substitutions in Radiolabeled Neurotensin Conjugates.

    PubMed

    Mascarin, Alba; Valverde, Ibai E; Mindt, Thomas L

    2016-01-05

    Radiolabeled derivatives of the peptide neurotensin (NT) and its binding sequence NT(8-13) have been studied as potential imaging probes and therapeutics for NT-1-receptor-positive cancer. However, a direct comparison of reported NT analogues, even if radiolabeled with the same radionuclide, is difficult because different techniques and models have been used for preclinical evaluations. In an effort to identify a suitable derivative of NT(8-13) for radiotracer development, we herein report a side-by-side in vitro comparison of radiometallated NT derivatives bearing some of the most commonly reported amino acid substitutions in their sequence. Performed investigations include cell internalization experiments, determinations of receptor affinity, measurements of the distribution coefficient, and blood serum stability studies. Of the [(177)Lu]-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-labeled examples studied, analogues of NT(8-13) containing a short hydrophilic tetraethylene glycol (PEG4 ) spacer between the peptide and the radiometal complex, and a minimum number of substitutions of amino acid residues, exhibited the most promising properties in vitro.

  14. Amino acid infusion blocks renal tubular uptake of an indium-labelled somatostatin analogue.

    PubMed Central

    Hammond, P. J.; Wade, A. F.; Gwilliam, M. E.; Peters, A. M.; Myers, M. J.; Gilbey, S. G.; Bloom, S. R.; Calam, J.

    1993-01-01

    The Indium-labelled somatostatin analogue pentetreotide has been successfully developed for imaging of somatostatin receptor positive tumours. However there is significant renal tubular uptake of the radiolabelled peptide, which can obscure upper abdominal tumours and would preclude its use for targeted radiotherapy. The aim of this study was to determine whether amino acid infusion, which has been shown to block renal tubular peptide reabsorption, diminishes renal parenchymal uptake of this radiolabelled analogue. Eight patients being scanned with the 111In-labelled somatostatin analogue, pentetreotide, for localisation of gastroenteropancreatic tumours received an infusion of synthetic amino acids. The ratio of isotope uptake in kidney to that in spleen was assessed, and compared to the ratio for matched control patients, to determine if amino acid infusion reduced renal parenchymal uptake of the radiopharmaceutical. The amount of isotope in the urine was determined to ensure that any effect of the amino acid infusion was unrelated to changes in clearance. Infusion of amino acids significantly reduced renal parenchymal uptake of isotope at 4 h. There was a non-significant increase in urinary clearance of isotope over the 4 h, consistent with reduced reuptake and a lack of effect on glomerular filtration rate. This technique, by preventing renal damage, may allow the use of this somatostatin analogue for local radiotherapy, and could be of wider value in blocking tubular re-uptake of potentially nephrotoxic agents, such as radiolabelled Fab fragments. Images Figure 1 PMID:8099808

  15. Actin-based motility of the intracellular pathogen Listeria monocytogenes: assessing the inhibitory specificity of ABM-1 peptide analogues.

    PubMed

    Purich, D L; Southwick, F S

    1999-06-01

    Actin-Based Motility motifs [ABM-1 sequence = (D/E)FPPPPX(D/E), where X = P or T, and ABM-2 sequence = XPPPPP, where X denotes G, A, L, P, and S] facilitate assembly of an activated motility complex. Potent inhibition of intracellular motility of pathogens by ABM-1 and ABM-2 peptide analogues has served as a criterion for investigating actin-based motility. To assess the specificity of ABM-1 peptide inhibitors, we microinjected proline-rich peptides into Listeria-infected PtK2 host cells. Use of a combinatorial ABM-1 peptide library (empirical formula = D1E2F2P4T1) demonstrated that high-potency inhibition requires a precise sequence, and not merely a particular amino acid composition. Calculated concentrations of specific sequences in this library indicate that the entire (D/E)FPPPPX(D/E) motif is needed to achieve high-affinity inhibition in living cells. The failure of the well known proline-rich SH3 binding antagonists VSL-12 or APP-12 to inhibit Listeria motility also indicates that SH3 interactions are unlikely to control actin-based motility directly.

  16. Synthesis and Pharmacological Characterization of Novel Glucagon-like Peptide-2 (GLP-2) Analogues with Low Systemic Clearance.

    PubMed

    Wiśniewski, Kazimierz; Sueiras-Diaz, Javier; Jiang, Guangcheng; Galyean, Robert; Lu, Mark; Thompson, Dorain; Wang, Yung-Chih; Croston, Glenn; Posch, Alexander; Hargrove, Diane M; Wiśniewska, Halina; Laporte, Régent; Dwyer, John J; Qi, Steve; Srinivasan, Karthik; Hartwig, Jennifer; Ferdyan, Nicky; Mares, Monica; Kraus, John; Alagarsamy, Sudarkodi; Rivière, Pierre J M; Schteingart, Claudio D

    2016-04-14

    Glucagon-like peptide-2 receptor agonists have therapeutic potential for the treatment of intestinal diseases. The native hGLP-2, a 33 amino acid gastrointestinal peptide, is not a suitable clinical candidate, due to its very short half-life in humans. In search of GLP-2 receptor agonists with better pharmacokinetic characteristics, a series of GLP-2 analogues containing Gly substitution at position 2, norleucine in position 10, and hydrophobic substitutions in positions 11 and/or 16 was designed and synthesized. In vitro receptor potency at the human GLP-2, selectivity vs the human GLP-1 and GCG receptors, and PK profile in rats were determined for the new analogues. A number of compounds more potent at the hGLP-2R than the native hormone, showing excellent receptor selectivity and very low systemic clearance (CL) were discovered. Analogues 69 ([Gly(2),Nle(10),D-Thi(11),Phe(16)]hGLP-2-(1-30)-NH2), 72 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-OH), 73 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NH2), 81 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NHEt), and 85 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NH-((CH2)2O)4-(CH2)2-CONH2) displayed the desired profiles (EC50 (hGLP-2R) < 100 pM, CL in rat <0.3 mL/min/kg, selective vs hGLP-1R and hGCGR). Compound 73 (FE 203799) was selected as a candidate for clinical development.

  17. Synthesis of fluorescent analogues of relaxin family peptides and their preliminary in vitro and in vivo characterization

    NASA Astrophysics Data System (ADS)

    Chan, Linda; Smith, Craig; Chua, Berenice; Lin, Feng; Bathgate, Ross; Separovic, Frances; Gundlach, Andrew; Hossain, M. Akhter; Wade, John

    2013-12-01

    Relaxin, a heterodimeric polypeptide hormone, is a key regulator of collagen metabolism and multiple vascular control pathways in humans and rodents. Its actions are mediated via its cognate G-protein-coupled receptor, RXFP1 although it also ‘pharmacologically’ activates RXFP2, the receptor for the related, insulin-like peptide 3 (INSL3), which has specific actions on reproduction and bone metabolism. Therefore, experimental tools to facilitate insights into the distinct biological actions of relaxin and INSL3 are required, particularly for studies of tissues containing both RXFP1 and RXFP2. Here, we chemically functionalized human (H2) relaxin, the RXFP1-selective relaxin analogue H2:A(4-24)(F23A), and INSL3 to accommodate a fluorophore without marked reduction in binding or activation propensity. Chemical synthesis of the two chains for each peptide was followed by sequential regioselective formation of their three disulfide bonds. Click chemistry conjugation of Cy5.5 at the B-chain N-terminus, with conservation of the disulfide bonds, yielded the analogues displaying appropriate selective binding affinity and ability to activate RXFP1 and/or RXFP2 in vitro. The in vivo biological activity of Cy5.5-H2 relaxin and Cy5.5-H2:A(4-24)(F23A) was confirmed in mice, as acute icv infusion of these peptides (but not Cy5.5-INSL3) stimulated water drinking, an established behavioral response elicited by central RXFP1 activation. The central distribution of Cy5.5-conjugated peptides was examined in mice killed 30 min after infusion, revealing fluorescence within brain tissue near-adjacent to the cerebral ventricle walls relative to deeper brain areas. These data will aid the interpretation of behavioral studies. Production of fluorophore-conjugated relaxin family peptides will facilitate future pharmacological studies to probe the function of H2 relaxin/RXFP1 and INSL3/RXFP2 signaling in vivo while tracking their distribution following central or peripheral administration.

  18. A novel long-acting glucose-dependent insulinotropic peptide analogue: enhanced efficacy in normal and diabetic rodents

    PubMed Central

    Tatarkiewicz, K; Hargrove, D M; Jodka, C M; Gedulin, B R; Smith, P A; Hoyt, J A; Lwin, A; Collins, L; Mamedova, L; Levy, O E; D’Souza, L; Janssen, S; Srivastava, V; Ghosh, S S; Parkes, D G

    2014-01-01

    Aim Glucose-dependent insulinotropic peptide (GIP) is an incretin hormone that is released from intestinal K cells in response to nutrient ingestion. We aimed to investigate the therapeutic potential of the novel N- and C-terminally modified GIP analogue AC163794. Methods AC163794 was synthesized by solid-phase peptide synthesis. Design involved the substitution of the C-terminus tail region of the dipeptidyl peptidase IV (DPP-IV)-resistant GIP analogue [d-Ala2]GIP(1–42) with the unique nine amino acid tail region of exenatide. The functional activity and binding of AC163794 to the GIP receptor were evaluated in RIN-m5F β-cells. In vitro metabolic stability was tested in human plasma and kidney membrane preparations. Acute insulinotropic effects were investigated in isolated mouse islets and during an intravenous glucose tolerance test in normal and diabetic Zucker fatty diabetic (ZDF) rats. The biological actions of AC163794 were comprehensively assessed in normal, ob/ob and high-fat-fed streptozotocin (STZ)-induced diabetic mice. Acute glucoregulatory effects of AC163794 were tested in diet-induced obese mice treated subchronically with AC3174, the exendatide analogue [Leu14] exenatide. Human GIP or [d-Ala2]GIP(1–42) were used for comparison. Results AC163794 exhibited nanomolar functional GIP receptor potency in vitro similar to GIP and [d-Ala2]GIP(1–42). AC163794 was metabolically more stable in vitro and displayed longer duration of insulinotropic action in vivo versus GIP and [d-Ala2]GIP(1–42). In diabetic mice, AC163794 improved HbA1c through enhanced insulinotropic action, partial restoration of pancreatic insulin content and improved insulin sensitivity with no adverse effects on fat storage and metabolism. AC163794 provided additional baseline glucose-lowering when injected to mice treated with AC3174. Conclusions These studies support the potential use of a novel GIP analogue AC163794 for the treatment of type 2 diabetes. PMID:23859463

  19. PACE4-Based Molecular Targeting of Prostate Cancer Using an Engineered 64Cu-Radiolabeled Peptide Inhibitor1☆☆

    PubMed Central

    Couture, Frédéric; Levesque, Christine; Dumulon-Perreault, Véronique; Ait-Mohand, Samia; D’Anjou, François; Day, Robert; Guérin, Brigitte

    2014-01-01

    The potential of PACE4 as a pharmacological target in prostate cancer has been demonstrated as this proprotein convertase is strongly overexpressed in human prostate cancer tissues and its inhibition, using molecular or pharmacological approaches, results in reduced cell proliferation and tumor progression in mouse tumor xenograft models. We developed a PACE4 high-affinity peptide inhibitor, namely, the multi-leucine (ML), and sought to determine whether this peptide could be exploited for the targeting of prostate cancer for diagnostic or molecular imaging purposes. We conjugated a bifunctional chelator 1,4,7-triazacyclononane-1,4,7- triacetic acid (NOTA) to the ML peptide for copper-64 (64Cu) labeling and positron emission tomography (PET)– based prostate cancer detection. Enzyme kinetic assays against recombinant PACE4 showed that the NOTA-modified ML peptide displays identical inhibitory properties compared to the unmodified peptide. In vivo biodistribution of the 64Cu/NOTA-ML peptide evaluated in athymic nude mice bearing xenografts of two human prostate carcinoma cell lines showed a rapid and high uptake in PACE4-expressing LNCaP tumor at an early time point and in PACE4-rich organs. Co-injection of unlabeled peptide confirmed that tumor uptake was target-specific. PACE4-negative tumors displayed no tracer uptake 15 minutes after injection, while the kidneys, demonstrated high uptake due to rapid renal clearance of the peptide. The present study supports the feasibility of using a 64Cu/NOTA-ML peptide for PACE4-targeted prostate cancer detection and PACE4 status determination by PET imaging but also provides evidence that ML inhibitor–based drugs would readily reach tumor sites under in vivo conditions for pharmacological intervention or targeted radiation therapy. PMID:25220591

  20. Mass balance approaches for estimating the intestinal absorption and metabolism of peptides and analogues: theoretical development and applications

    NASA Technical Reports Server (NTRS)

    Sinko, P. J.; Leesman, G. D.; Amidon, G. L.

    1993-01-01

    A theoretical analysis for estimating the extent of intestinal peptide and peptide analogue absorption was developed on the basis of a mass balance approach that incorporates convection, permeability, and reaction. The macroscopic mass balance analysis (MMBA) was extended to include chemical and enzymatic degradation. A microscopic mass balance analysis, a numerical approach, was also developed and the results compared to the MMBA. The mass balance equations for the fraction of a drug absorbed and reacted in the tube were derived from the general steady state mass balance in a tube: [formula: see text] where M is mass, z is the length of the tube, R is the tube radius, Pw is the intestinal wall permeability, kr is the reaction rate constant, C is the concentration of drug in the volume element over which the mass balance is taken, VL is the volume of the tube, and vz is the axial velocity of drug. The theory was first applied to the oral absorption of two tripeptide analogues, cefaclor (CCL) and cefatrizine (CZN), which degrade and dimerize in the intestine. Simulations using the mass balance equations, the experimental absorption parameters, and the literature stability rate constants yielded a mean estimated extent of CCL (250-mg dose) and CZN (1000-mg dose) absorption of 89 and 51%, respectively, which was similar to the mean extent of absorption reported in humans (90 and 50%). It was proposed previously that 15% of the CCL dose spontaneously degraded systematically; however, our simulations suggest that significant CCL degradation occurs (8 to 17%) presystemically in the intestinal lumen.(ABSTRACT TRUNCATED AT 250 WORDS).

  1. Acute effects of the glucagon-like peptide 2 analogue, teduglutide, on intestinal adaptation in short bowel syndrome.

    PubMed

    Thymann, Thomas; Stoll, Barbara; Mecklenburg, Lars; Burrin, Douglas G; Vegge, Andreas; Qvist, Niels; Eriksen, Thomas; Jeppesen, Palle B; Sangild, Per T

    2014-06-01

    Neonatal short bowel syndrome following massive gut resection is associated with malabsorption of nutrients. The intestinotrophic factor glucagon-like peptide 2 (GLP-2) improves gut function in adult patients with short bowel syndrome, but its effect in pediatric patients remains unknown. Our objective was to test the efficacy of the long-acting synthetic human GLP-2 analogue, teduglutide (ALX-0600), in a neonatal piglet jejunostomy model. Two-day-old pigs were subjected to resection of 50% of the small intestine (distal part), and the remnant intestine was exteriorized on the abdominal wall as a jejunostomy. All pigs were given total parenteral nutrition for 7 days and a single daily injection of the following doses of teduglutide: 0.01 (n = 6), 0.02 (n = 6), 0.1 (n = 5), or 0.2 mg · kg · day (n = 6), and compared with placebo (n = 9). Body weight increment was similar for all 4 teduglutide groups but higher than placebo (P < 0.05). There was a dose-dependent increase in weight per length of the remnant intestine (P < 0.01) and fractional protein synthesis rate in the intestine was increased in the 0.2 mg · kg · day group versus placebo (P < 0.001); however, functional and structural endpoints including activity of digestive enzymes, absorption of enteral nutrients, and immunohistochemistry (Ki67, villin, FABP2, ChgA, and GLP-2R) were not affected by the treatment. Teduglutide induces trophicity on the remnant intestine but has limited acute effects on functional endpoints. Significant effects of teduglutide on gut function may require a longer adaptation period and/or a more frequent administration of the peptide. In perspective, GLP-2 or its analogues may be relevant to improve intestinal adaptation in pediatric patients with short bowel syndrome.

  2. Novel peptide chemistry in terrestrial animals: natural luciferin analogues from the bioluminescent earthworm Fridericia heliota.

    PubMed

    Dubinnyi, Maxim A; Tsarkova, Aleksandra S; Petushkov, Valentin N; Kaskova, Zinaida M; Rodionova, Natalja S; Kovalchuk, Sergey I; Ziganshin, Rustam H; Baranov, Mikhail S; Mineev, Konstantin S; Yampolsky, Ilia V

    2015-03-02

    We report isolation and structure elucidation of AsLn5, AsLn7, AsLn11 and AsLn12: novel luciferin analogs from the bioluminescent earthworm Fridericia heliota. They were found to be highly unusual modified peptides, comprising either of the two tyrosine-derived chromophores, CompX or CompY and a set of amino acids, including threonine, gamma-aminobutyric acid, homoarginine, and unsymmetrical N,N-dimethylarginine. These natural compounds represent a unique peptide chemistry found in terrestrial animals and rise novel questions concerning their biosynthetic origin.

  3. Differentiating effects of the glucagon-like peptide-1 analogue exendin-4 in a human neuronal cell model.

    PubMed

    Luciani, Paola; Deledda, Cristiana; Benvenuti, Susanna; Cellai, Ilaria; Squecco, Roberta; Monici, Monica; Cialdai, Francesca; Luciani, Giorgia; Danza, Giovanna; Di Stefano, Chiara; Francini, Fabio; Peri, Alessandro

    2010-11-01

    Glucagon-like peptide-1 (GLP-1) is an insulinotropic peptide with neurotrophic properties, as assessed in animal cell models. Exendin-4, a GLP-1 analogue, has been recently approved for the treatment of type 2 diabetes mellitus. The aim of this study was to morphologically, structurally, and functionally characterize the differentiating actions of exendin-4 using a human neuronal cell model (i.e., SH-SY5Y cells). We found that exendin-4 increased the number of neurites paralleled by dramatic changes in intracellular actin and tubulin distribution. Electrophysiological analyses showed an increase in cell membrane surface and in stretch-activated-channels sensitivity, an increased conductance of Na(+) channels and amplitude of Ca(++) currents (T- and L-type), typical of a more mature neuronal phenotype. To our knowledge, this is the first demonstration that exendin-4 promotes neuronal differentiation in human cells. Noteworthy, our data support the claimed favorable role of exendin-4 against diabetic neuropathy as well as against different neurodegenerative diseases.

  4. New proctolin analogues modified by D-amino acids in the peptide chain and their high cardioexcitatory effect on Tenebrio molitor.

    PubMed

    Kuczer, M; Rosiński, G; Lisowski, M; Picur, B; Konopiñska, D

    1996-09-01

    The object of our studies was the synthesis and conformational and biological evaluation of the series of 14 analogues of the insect neuropeptide, proctolin. The analogues were obtained by replacement of the native L-amino acids by their D-isomers in one, two, and all positions. Biological effects of the peptides were examined by cardioexcitatory test on the heart of yellow mealworm, Tenebrio molitor, in vitro. In biotest performed on insects, D-Arg-D-Tyr-D-Leu-D-Pro-D-Thr, [D-Arg(N-G-nitro)1,D-Leu3]-, [D-Arg1,D-Leu3]-, [D-Tyr2,D-Thr5]- and [D-Arg1,D-Pro4]-proctolin exert high agonistic activity of proctolin on the heart of insects at 10(-11) - 10(-10) M concentrations. The proctolin analogue containing only D-amino acid residues in the peptide chain unexpectedly shows a much higher cardioexcitatory effect than the native peptide. Moreover, preliminary CD and NMR conformational studies show that proctolin analogues investigated here seem to prefer rather ordered structures, although their conformations differ in some cases.

  5. Novel C2-C3' N-peptide linked macrocyclic taxoids. Part 2: synthesis and biological activities of docetaxel analogues with a peptide side chain at C2 and their macrocyclic derivatives.

    PubMed

    Larroque, Anne-Laure; Dubois, Joëlle; Thoret, Sylviane; Aubert, Geneviève; Chiaroni, Angèle; Guéritte, Françoise; Guénard, Daniel

    2007-01-01

    The synthesis of a series of novel docetaxel analogues possessing a peptide side chain at the C2 position as well as peptide macrocyclic taxoids is described. These compounds were designed to mimic a region of the alpha-tubulin loop equivalent to the paclitaxel binding pocket of beta-tubulin. Fifteen new peptide taxoids were obtained and evaluated as inhibitors of microtubule disassembly as well as cell proliferation. The relationships between these new taxoids and the tau protein motif interacting with microtubules are discussed.

  6. Antimicrobial Peptide from the Wild Bee Hylaeus signatus Venom and Its Analogues: Structure-Activity Study and Synergistic Effect with Antibiotics.

    PubMed

    Nešuta, Ondřej; Hexnerová, Rozálie; Buděšínský, Miloš; Slaninová, Jiřina; Bednárová, Lucie; Hadravová, Romana; Straka, Jakub; Veverka, Václav; Čeřovský, Václav

    2016-04-22

    Venoms of hymenopteran insects have attracted considerable interest as a source of cationic antimicrobial peptides (AMPs). In the venom of the solitary bee Hylaeus signatus (Hymenoptera: Colletidae), we identified a new hexadecapeptide of sequence Gly-Ile-Met-Ser-Ser-Leu-Met-Lys-Lys-Leu-Ala-Ala-His-Ile-Ala-Lys-NH2. Named HYL, it belongs to the category of α-helical amphipathic AMPs. HYL exhibited weak antimicrobial activity against several strains of pathogenic bacteria and moderate activity against Candida albicans, but its hemolytic activity against human red blood cells was low. We prepared a set of HYL analogues to evaluate the effects of structural modifications on its biological activity and to increase its potency against pathogenic bacteria. This produced several analogues exhibiting significantly greater activity compared to HYL against strains of both Staphylococcus aureus and Pseudomonas aeruginosa even as their hemolytic activity remained low. Studying synergism of HYL peptides and conventional antibiotics showed the peptides act synergistically and preferentially in combination with rifampicin. Fluorescent dye propidium iodide uptake showed the tested peptides were able to facilitate entrance of antibiotics into the cytoplasm by permeabilization of the outer and inner bacterial cell membrane of P. aeruginosa. Transmission electron microscopy revealed that treatment of P. aeruginosa with one of the HYL analogues caused total disintegration of bacterial cells. NMR spectroscopy was used to elucidate the structure-activity relationship for the effect of amino acid residue substitution in HYL.

  7. Accumulation of acyl-enzyme in DD-peptidase-catalysed reactions with analogues of peptide substrates.

    PubMed Central

    Jamin, M; Adam, M; Damblon, C; Christiaens, L; Frère, J M

    1991-01-01

    Thioester substrates can be used to study the hydrolysis and transfer reactions catalysed by beta-lactamases and DD-peptidases. With the latter enzymes, accumulation of the acyl-enzyme can be detected directly. The efficiency of various amines as acceptor substrates was in excellent agreement with previous results obtained with peptide substrates of the DD-peptidases. The results indicated the presence of a specific binding site for the acceptor substrates. Although most of the results agreed well with a simple partition model, more elaborate hypotheses will be needed to account for all the data presented. PMID:1747125

  8. The role played by lipids unsaturation upon the membrane interaction of the Helicobacter pylori HP(2-20) antimicrobial peptide analogue HPA3.

    PubMed

    Mereuta, Loredana; Luchian, Tudor; Park, Yoonkynung; Hahm, Kyung-Soo

    2009-02-01

    The HPA3 peptide is an analogue of the linear antimicrobial peptide, HP(2-20), isolated from the N-terminal region of the Helicobacter pylori ribosomal protein, able to interact with zwitterionic lipid membranes and generate pores. Herein we focused on the importance of the degree of unsaturation of lipid acyl chains on HPA3 peptide-membrane interactions. Electrophysiology experiments carried out in reconstituted lipid membranes formed from phosphatidylcholines with one (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine - POPC) and two monounsaturated acyl chains (1,2-dioleoyl-sn-glycero-3-phosphocholine - DOPC) demonstrate that the lesser degree of the packing density of membrane lipids encountered in DOPC-based planar membranes greatly enhances the electric activity of pores created by the HPA3 peptide. Data derived from fluorescence spectroscopy experiments demonstrate that upon interaction with the bilayer, the HPA3 peptide translocates to the trans-side of the membrane. From the same experiments, we demonstrate that in the case of DOPC-based planar membranes, the net amount of HPA3 peptide which passes across the membrane and re-dissolves in the trans solution is almost 22% greater than POPC-based membranes. Such data further emphasize the modulatory role played by lipid acyl chain in determining antimicrobial peptides-lipids interactions, and demonstrate that small differences in unsaturation degree can impose a sizeable influence on HPA3 peptide activity.

  9. Radiolabeled bombesin derivatives for preclinical oncological imaging

    PubMed Central

    de Aguiar Ferreira, Carolina; Fuscaldi, Leonardo Lima; Townsend, Danyelle M.; Rubello, Domenico; de Barros, André Luís Branco

    2017-01-01

    Despite efforts, cancer is still one of the leading causes of morbidity and mortality worldwide, with approximately 14 million new cases and 8.2 million cancer-related deaths each year, according to the World Health Organization. Among the strategies to reduce cancer progression and improving its management, implementing early detection technologies is crucial. Based on the fact that several types of cancer cells overexpress surface receptors, small molecule ligands, such as peptides, have been developed to allow tumor identification at earlier stages. Allied with imaging techniques such as PET and SPECT, radiolabeled peptides play a pivotal role in nuclear medicine. Bombesin, a peptide of 14 amino acids, is an amphibian homolog to the mammalian gastrin-releasing peptide (GRP), that has been extensively studied as a targeting ligand for diagnosis and therapy of GRP positive tumors, such as breast, pancreas, lungs and prostate cancers. In this context, herein we provide a review of reported bombesin derivatives radiolabeled with a multitude of radioactive isotopes for diagnostic purposes in the preclinical setting. Moreover, since animal models are highly relevant for assessing the potential of clinical translation of this radiopeptides, a brief report of the currently used GRP-positive tumor-bearing animal models is described. PMID:28040598

  10. Single-molecule investigation of the interactions between reconstituted planar lipid membranes and an analogue of the HP(2-20) antimicrobial peptide.

    PubMed

    Mereuta, Loredana; Luchian, Tudor; Park, Yoonkyung; Hahm, Kyung-Soo

    2008-09-05

    In this study, we employed electrophysiology experiments carried out at the single-molecule level to study the mechanism of action of the HPA3 peptide, an analogue of the linear antimicrobial peptide, HP(2-20), isolated from the N-terminal region of the Helicobacter pylori ribosomal protein. Amplitude analysis of currents fluctuations induced by HPA3 peptide at various potentials in zwitterionic lipid membranes reveal the existence of reproducible conductive states in the stochastic behavior of such events, which directly supports the existence of transmembrane pores induced the peptide. From our data recorded both at the single-pore and macroscopic levels, we propose that the HPA3 pore formation is electrophoretically facilitated by trans-negative transmembrane potentials, and HPA3 peptides translocate into the trans monolayers after forming the pores. We present evidence according to which the decrease in the membrane dipole potential of a reconstituted lipid membranes leads to an augmentation of the membrane activity of HPA3 peptides, and propose that a lower electric dipole field of the interfacial region of the membrane caused by phloretin facilitates the surface-bound HPA3 peptides to break free from one leaflet of the membrane, insert into the membrane and contribute to pore formation spanning the entire thickness of the membrane.

  11. Single-molecule investigation of the interactions between reconstituted planar lipid membranes and an analogue of the HP(2-20) antimicrobial peptide

    SciTech Connect

    Mereuta, Loredana; Luchian, Tudor Park, Yoonkyung; Hahm, Kyung-Soo

    2008-09-05

    In this study, we employed electrophysiology experiments carried out at the single-molecule level to study the mechanism of action of the HPA3 peptide, an analogue of the linear antimicrobial peptide, HP(2-20), isolated from the N-terminal region of the Helicobacter pylori ribosomal protein. Amplitude analysis of currents fluctuations induced by HPA3 peptide at various potentials in zwitterionic lipid membranes reveal the existence of reproducible conductive states in the stochastic behavior of such events, which directly supports the existence of transmembrane pores induced the peptide. From our data recorded both at the single-pore and macroscopic levels, we propose that the HPA3 pore formation is electrophoretically facilitated by trans-negative transmembrane potentials, and HPA3 peptides translocate into the trans monolayers after forming the pores. We present evidence according to which the decrease in the membrane dipole potential of a reconstituted lipid membranes leads to an augmentation of the membrane activity of HPA3 peptides, and propose that a lower electric dipole field of the interfacial region of the membrane caused by phloretin facilitates the surface-bound HPA3 peptides to break free from one leaflet of the membrane, insert into the membrane and contribute to pore formation spanning the entire thickness of the membrane.

  12. Accurate Characterization of the Peptide Linkage in the Gas Phase: a Joint Quantum-Chemical and Rotational Spectroscopy Study of the Glycine Dipeptide Analogue

    NASA Astrophysics Data System (ADS)

    Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo; Largo, Laura; Peña, Isabel; Cabezas, Carlos; Alonso, José L.

    2014-06-01

    Accurate structures of aminoacids in the gas phase have been obtained by joint microwave and quantum-chemical investigations. However, the structure and conformational behavior of α-aminoacids once incorporated into peptide chains are completely different and have not yet been characterized with the same accuracy. To fill this gap, we present here an accurate characterization of the simplest dipeptide analogue (N-acetylglycinamide) involving peptidic bonds. State-of-the-art quantum-chemical computations are complemented by a comprehensive study of the rotational spectrum using a combination of Fourier transform microwave spectroscopy with laser ablation. The coexistence of the C_7 and C_5 conformers has been proved and energetically as well as spectroscopically characterized. This joint theoretical-experimental investigation demonstrated the feasibility of obtaining accurate structures for flexible small biomolecules, thus paving the route to the elucidation of the inherent behavior of peptides.

  13. Structural characterization of native autoinducing peptides and abiotic analogues reveals key features essential for activation and inhibition of an AgrC quorum sensing receptor in Staphylococcus aureus.

    PubMed

    Tal-Gan, Yftah; Ivancic, Monika; Cornilescu, Gabriel; Cornilescu, Claudia C; Blackwell, Helen E

    2013-12-11

    Staphylococcus aureus is a major human pathogen that uses quorum sensing (QS) to control virulence. Its QS system is regulated by macrocyclic peptide signals (or autoinducing peptides (AIPs)) and their cognate transmembrane receptors (AgrCs). Four different specificity groups of S. aureus have been identified to date (groups I-IV), each of which uses a different AIP:AgrC pair. Non-native ligands capable of intercepting AIP:AgrC binding, and thereby QS, in S. aureus have attracted considerable interest as chemical tools to study QS pathways and as possible antivirulence strategies for the treatment of infection. We recently reported a set of analogues of the group-III AIP that are capable of strongly modulating the activity of all four AgrC receptors. Critical to the further development of such ligands is a detailed understanding of the structural features of both native AIPs and non-native analogues that are essential for activity. Herein, we report the first three-dimensional structural analysis of the known native AIP signals (AIPs-I-IV) and several AIP-III analogues with varied biological activities using NMR spectroscopy. Integration of these NMR studies with the known agonism and antagonism profiles of these peptides in AgrC-III revealed two key structural elements that control AIP-III (and non-native peptide) activity: (1) a tri-residue hydrophobic "knob" essential for both activation and inhibition and (2) a fourth anchor point on the exocyclic tail needed for receptor activation. These results provide strong structural support for a mechanism of AIP-mediated AgrC activation and inhibition in S. aureus , and should facilitate the design of new AgrC ligands with enhanced activities (as agonists or antagonists) and simplified chemical structures.

  14. A novel peptide sansalvamide analogue inhibits pancreatic cancer cell growth through G0/G1 cell-cycle arrest

    SciTech Connect

    Ujiki, Michael B. |; Milam, Ben; Ding Xianzhong |; Roginsky, Alexandra B.; Salabat, M. Reza; Talamonti, Mark S.; Bell, Richard H. |; Gu Wenxin; Silverman, Richard B. ||; Adrian, Thomas E. |. E-mail: tadrian@northwestern.edu

    2006-02-24

    Patients with pancreatic cancer have little hope for cure because no effective therapies are available. Sansalvamide A is a cyclic depsipeptide produced by a marine fungus. We investigated the effect of a novel sansalvamide A analogue on growth, cell-cycle phases, and induction of apoptosis in human pancreatic cancer cells in vitro. The sansalvamide analogue caused marked time- and concentration-dependent inhibition of DNA synthesis and cell proliferation of two human pancreatic cancer cell lines (AsPC-1 and S2-013). The analogue induced G0/G1 phase cell-cycle arrest and morphological changes suggesting induction of apoptosis. Apoptosis was confirmed by annexin V binding. This novel sansalvamide analogue inhibits growth of pancreatic cancer cells through G0/G1 arrest and induces apoptosis. Sansalvamide analogues may be valuable for the treatment of pancreatic cancer.

  15. Clinical application of radiolabelled platelets

    SciTech Connect

    Kessler, C. )

    1990-01-01

    This book presents papers on the clinical applications of radiolabelled platelets. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection.

  16. Ex Vivo Smooth Muscle Pharmacological Effects of a Novel Bradykinin-Related Peptide, and Its Analogue, from Chinese Large Odorous Frog, Odorrana livida Skin Secretions

    PubMed Central

    Xiang, Jie; Wang, Hui; Ma, Chengbang; Zhou, Mei; Wu, Yuxin; Wang, Lei; Guo, Shaodong; Chen, Tianbao; Shaw, Chris

    2016-01-01

    Bradykinin-related peptides (BRPs) are one of the most extensively studied frog secretions-derived peptide families identified from many amphibian species. The diverse primary structures of BRPs have been proven essential for providing valuable information in understanding basic mechanisms associated with drug modification. Here, we isolated, identified and characterized a dodeca-BRP (RAP-L1, T6-BK), with primary structure RAPLPPGFTPFR, from the skin secretions of Chinese large odorous frogs, Odorrana livida. This novel peptide exhibited a dose-dependent contractile property on rat bladder and rat ileum, and increased the contraction frequency on rat uterus ex vivo smooth muscle preparations; it also showed vasorelaxant activity on rat tail artery smooth muscle. In addition, the analogue RAP-L1, T6, L8-BK completely abolished these effects on selected rat smooth muscle tissues, whilst it showed inhibition effect on bradykinin-induced rat tail artery relaxation. By using canonical antagonist for bradykinin B1 or B2 type receptors, we found that RAP-L1, T6-BK -induced relaxation of the arterial smooth muscle was very likely to be modulated by B2 receptors. The analogue RAP-L1, T6, L8-BK further enhanced the bradykinin inhibitory activity only under the condition of co-administration with HOE140 on rat tail artery, suggesting a synergistic inhibition mechanism by which targeting B2 type receptors. PMID:27690099

  17. Radiolabeled antibodies in cancer. Oncology Overview

    SciTech Connect

    Not Available

    1984-11-01

    Oncology Overviews are a service of the International Cancer Research Data Bank (ICRDB) Program of the National Cancer Institute, intended to facilitate and promote the exchange of information between cancer scientists by keeping them aware of literature related to their research being published by other laboratories through the world. Each Oncology Overview represents a survey of the literature associated with a selected area of cancer research. It contains abstracts of articles which have been selected and organized by researchers associated with the field. Contents: Radiolabeled antibodies--labeling and imaging techniques; Radiolabeled antibodies--carcinoembryonic antigen; Radiolabeled antibodies--alpha-fetoprotein; Radiolabeled antibodies--human chorionic gonadotropin; Radiolabeled antibodies--ferritin; Radiolabeled antibodies--imaging of colorectal tumors; Radiolabeled antibodies--imaging of malignant melanoma; Radiolabeled antibodies--imaging of urogenital tumors; Radiolabeled antibodies--imaging of thyroid tumors; Radiolabeled antibodies--other clinical studies; Radiolabeled antibodies--selected preclinical studies; Radiolabeled antibodies--reviews.

  18. Examination of methods for the preparation of biologically active radiolabeled melanotropins

    SciTech Connect

    Heward, C.B.

    1982-01-01

    The present studies were initiated to develop a radioactive melanotropin with full, or nearly full, biological activity. This labeled melanotropin must be of sufficient specific radioactivity to be suitable as a tracer in a radioreceptor assay and ultimately as a marker for in vivo tumor localization. The studies described herein provide information concerning: chloramine T induced iodination, lactoperoxidase catelyzed iodination, and iodogen induced iodination of ..cap alpha..-MSH and certain structural analogues. Radio-labeled derivatives of various melanotropins were prepared using a variety of iodination techniques. Under conditions commonly used for the iodination of other peptides a substantial loss of biological activity of the native hormone (..cap alpha..-MSH) was observed. Under similar iodination conditions using 4-norleucine-alpha-melanotropin ((NIe/sup 4/)-..cap alpha..-MSH), satisfactory incorporation of label into the peptide was accomplished without significant loss of biological activity. Data are presented suggesting that this peptide is far superior to ..cap alpha..-MSH for use in the preparation of a radioactive melanotropin. Although some success was achieved using (NIe/sup 4/)-..cap alpha..-MSH with all three iodination methods, the simplest and most consistent method involved the use of iodogen followed by purification of the labeled product using high performance liquid chromatography (HPLC).

  19. A strategy for fusion expression and preparation of functional glucagon-like peptide-1 (GLP-1) analogue by introducing an enterokinase cleavage site.

    PubMed

    Liu, Yang; Ren, Limei; Ge, Lingmiao; Cui, Qingxin; Cao, Xiaofang; Hou, Yuanyuan; Bai, Fang; Bai, Gang

    2014-08-01

    KGLP-1, a 31-amino acid glucagon-like peptide-1 (GLP-1) analogue, has a great therapeutic potential for anti-diabetes. In this work, a strategy for expression and purification of functional KGLP-1 peptide has been established. KGLP-1 cDNA was fused with glutathione S-transferase (GST), with an enterokinase cleavage site in the fusion junction. The recombinant fusion protein GST-KGLP-1 was affinity purified via the GST-tag, and then digested with enterokinase. The resulting GST part as well as the enzymes were eliminated by ultra-filtration followed by size exclusion chromatograph. The yield of purified KGLP-1 was approximately 12.1 mg/L, with purity of 96.18 %. The recombinant KGLP-1 was shown to have similar bioactivity as native GLP-1 when evaluated in a Chinese hamster ovary cell line expressing a GLP-1 receptor-egfp reporter gene.

  20. Comprehensive radiolabeling, stability, and tissue distribution studies of technetium-99m single amino acid chelates (SAAC).

    PubMed

    Maresca, Kevin P; Hillier, Shawn M; Femia, Frank J; Zimmerman, Craig N; Levadala, Murali K; Banerjee, Sangeeta R; Hicks, Justin; Sundararajan, Chitra; Valliant, John; Zubieta, Jon; Eckelman, William C; Joyal, John L; Babich, John W

    2009-08-19

    Technetium tricarbonyl chemistry has been a subject of interest in radiopharmaceutical development over the past decade. Despite the extensive work done on developing chelates for Tc(I), a rigorous investigation of the impact of changing donor groups and labeling conditions on radiochemical yields and/or distribution has been lacking. This information is crucially important if these platforms are going to be used to develop molecular imaging probes. Previous studies on the coordination chemistry of the {M(CO)(3)}(+) core have established alkylamine, aromatic nitrogen heterocycles, and carboxylate donors as effective chelating ligands. These observations led to the design of tridentate ligands derived from the amino acid lysine. Such amino acid analogues provide a tridentate donor set for chelation to the metal and an amino acid functionality for conjugation to biomolecules. We recently developed a family of single amino acid chelates (SAAC) that serve this function and can be readily incorporated into peptides via solid-phase synthesis techniques. As part of these continuing studies, we report here on the radiolabeling with technetium-99m ((99m)Tc) and stability of a series of SAAC analogues of lysine. The complexes studied include cationic, neutral, and anionic complexes. The results of tissue distribution studies with these novel complexes in normal rats demonstrate a range of distribution in kidney, liver, and intestines.

  1. Novel dual agonist peptide analogues derived from dogfish glucagon show promising in vitro insulin releasing actions and antihyperglycaemic activity in mice.

    PubMed

    O'Harte, F P M; Ng, M T; Lynch, A M; Conlon, J M; Flatt, P R

    2016-08-15

    The antidiabetic potential of thirteen novel dogfish glucagon derived analogues were assessed in vitro and in acute in vivo studies. Stable peptide analogues enhanced insulin secretion from BRIN-BD11 β-cells (p < 0.001) and reduced acute glycaemic responses following intraperitoneal glucose (25 nmol/kg) in healthy NIH Swiss mice (p < 0.05-p<0.001). The in vitro insulinotropic actions of [S2a]dogfish glucagon, [S2a]dogfish glucagon-exendin-4(31-39) and [S2a]dogfish glucagon-Lys(30)-γ-glutamyl-PAL, were blocked (p < 0.05-p<0.001) by the specific GLP-1 and glucagon receptor antagonists, exendin-4(9-39) and (desHis(1)Pro(4)Glu(9))glucagon amide but not by (Pro(3))GIP, indicating lack of GIP receptor involvement. These analogues dose-dependently stimulated cAMP production in GLP-1 and glucagon (p < 0.05-p<0.001) but not GIP-receptor transfected cells. They improved acute glycaemic and insulinotropic responses in high-fat fed diabetic mice and in wild-type C57BL/6J and GIPR-KO mice (p < 0.05-p<0.001), but not GLP-1R-KO mice, confirming action on GLP-1 but not GIP receptors. Overall, dogfish glucagon analogues have potential for diabetes therapy, exerting beneficial metabolic effects via GLP-1 and glucagon receptors.

  2. Brevinin-2-related peptide and its [D4K] analogue stimulate insulin release in vitro and improve glucose tolerance in mice fed a high fat diet.

    PubMed

    Abdel-Wahab, Y H A; Patterson, S; Flatt, P R; Conlon, J M

    2010-08-01

    The cationic, alpha-helical frog skin antimicrobial peptide B2RP (brevinin-2-related peptide) shows sequence similarity to antimicrobial peptides belonging to the brevinin-2 family, but lacks the C-terminal cyclic heptapeptide domain (Cys-Lys-Xaa (4)-Cys). Synthetic B2RP produced a significant (p<0.05) stimulation of insulin release (148% of basal rate at a concentration of 1 muM with a maximum response of 222% of basal rate at a concentration of 3 muM) from BRIN-BD11 clonal beta-cells without increasing the release of the cytosolic enzyme, lactate dehydrogenase. Increasing cationicity of B2RP while maintaining amphipathicity by the substitution Asp (4) --> Lys enhanced the insulin-releasing potency (137% of basal rate at a concentration of 0.3 muM; p<0.05) with no stimulation of lactate dehydrogenase release. In contrast, the L18K, and D4K, L18K analogues were toxic to the cells, and the K16A analogue, with increased amphipathicity and hydrophobicity, showed reduced potency. Administration of [D4K]B2RP (100 nmol/kg body weight) to mice fed a high fat diet to induce obesity and insulin-resistance significantly (p<0.05) enhanced insulin release and improved glucose tolerance during the 60-minute period following an intraperitoneal glucose load (18 mmol/kg body weight). B2RP shows potential for development into an agent for the treatment of type 2 diabetes.

  3. Inhibition of pepsin by analogues of pepsinogen-(1-12)-peptide with substitutions in the 4-7 sequence region.

    PubMed Central

    Dunn, B M; Lewitt, M; Pham, C

    1983-01-01

    Derivatives of the 1-12 sequence of pig pepsinogen were prepared by solid-phase peptide synthesis. The three derivatives contain substitutions in the 4-7 region of the 1-12 sequence. Glycine was used to replace the hydrophobic residues -Val-Pro-Leu-Val- in pairs. After cleavage and purification, the synthetic peptides were compared with a synthetic peptide of the native sequence, prepared at the same time, with respect to their ability to inhibit the pepsin-catalysed clotting of milk. Inhibitory potency, determined from plots of percentage inhibition versus concentration of synthetic peptide, is inversely correlated with the substitution of glycine residues for the hydrophobic residues. Therefore the equilibrium inhibition of pepsin by these peptides is dominated by the hydrophobic nature of the 4-7 sequence region. PMID:6405735

  4. Synthesis and radiolabeling of a somatostatin analog for multimodal imaging

    NASA Astrophysics Data System (ADS)

    Edwards, W. Barry; Liang, Kexian; Xu, Baogang; Anderson, Carolyn J.; Achilefu, Samuel

    2006-02-01

    A new multimodal imaging agent for imaging the somatostatin receptor has been synthesized and evaluated in vitro and in vivo. A somatostatin analog, conjugated to both 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaceticacid (DOTA) and cypate (BS-296), was synthesized entirely on the solid phase (Fmoc) and purified by RP-HPLC. DOTA was added as a ligand for radiometals such as 64Cu or 177Lu for either radio-imaging or radiotherapy respectively. Cytate, a cypatesomatostatin analog conjugate, has previously demonstrated the ability to visualize somatostatin receptor rich tumor xenografts and natural organs by optical imaging techniques. BS-296 exhibited low nanomolar inhibitory capacity toward the binding of radiolabeled somatostatin analogs in cell membranes enriched in the somatostatin receptor, demonstrating the high affinity of this multimodal imaging peptide and indicating its potential as a molecular imaging agent. 64Cu, an isotope for diagnostic imaging and radiotherapy, was selected as the isotope for radiolabeling BS-296. BS-296 was radiolabeled with 64Cu in high specific activity (200 μCi/μg) in 90% radiochemical yield. Addition of 2,5-dihydroxybenzoic acid (gentisic acid) prevented radiolysis of the sample, allowing for study of the 64Cu -BS-296 the day following radiolabeling. Furthermore, inclusion of DMSO at a level of 20% was found not to interfere with radiolabeling yields and prevented the adherence of 64Cu -BS-296 to the walls of the reaction vessel.

  5. Clearance and early hydrolysis of atrial natriuretic factor in vivo. Structural analysis of cleavage sites and design of an analogue that inhibits hormone cleavage.

    PubMed Central

    Condra, C L; Leidy, E A; Bunting, P; Colton, C D; Nutt, R F; Rosenblatt, M; Jacobs, J W

    1988-01-01

    This study examines the clearance and early hydrolysis of atrial natriuretic factor (ANF) in vivo. Radiolabeled ANF was cleared from the circulation of the rat with biphasic kinetics; the majority (90%) of ANF cleared with a t1/2 of 15 s, the remaining peptide was cleared with a t1/2 of 5 min. Microsequence analysis of ANF peptides recovered from the circulation of rats revealed five major degradation products of the intact hormone. The first cleavage occurred between amino acids 12 and 13 of the hormone and would inactivate ANF. Over time, additional fragments of the hormone were generated, including fragments of 6, 7, 21, and 24 amino acids in length. Whole body radioautography of rats injected with [123I]-ANF revealed the kidney as a predominant organ involved in clearance of ANF. Subsequent amino acid sequence analyses of radiolabeled ANF exposed to the kidney in vivo indicated that this organ generated four of the five major hydrolysis products observed in circulation, namely, the 6, 7, 16, and 21 amino acid fragments of the hormone. In an attempt to stabilize ANF in vivo, a synthetic analogue of the hormone was prepared that contained the amino acid analogue, aminoisobutyric acid, substituted at position 13. This analogue completely abolished the in vivo cleavage of ANF at this site. These studies demonstrate the usefulness of a protein chemistry approach in characterizing hormone metabolism in vivo and designing analogues with enhanced in vivo stability to cleavage. Images PMID:2966813

  6. Synthesis and evaluation of a novel series of farnesyl protein transferase inhibitors as non-peptidic CAAX tetrapeptide analogues.

    PubMed

    Perez, Michel; Maraval, Catherine; Dumond, Stephan; Lamothe, Marie; Schambel, Philippe; Etiévant, Chantal; Hill, Bridget

    2003-04-17

    A novel series of compounds, derived from 4-amino-phenyl piperazine, has been designed to selectively inhibit farnesyl protein transferase (FPTase) as CAAX tetrapeptide analogues. Certain of these compounds were shown to possess low nanomolar inhibitory activity both against the isolated enzyme and in cultured cells.

  7. PET with radiolabeled aminoacid.

    PubMed

    Crippa, F; Alessi, A; Serafini, G L

    2012-04-01

    Since the clinical introduction of FDG, neuroimaging has been the first area of PET application in oncology. Later, while FDG-PET became progressively a key imaging modality in the management of the majority of malignancies outside the brain, its neuro-oncologic indications faced some limitations because of the unfavourable characteristics of FDG as brain tumor-seeking agent. PET applications in neuro-oncology have received new effectiveness by the advent of positron-emission labelled amino acids, so that it has been coined the term "Amino acid PET" to differentiate this imaging tool from FDG-PET. Radiolabeled amino acids are a very interesting class of PET tracers with great diagnostic potential in neuro-oncology because of their low uptake in normal brain and, conversely, high uptake in most brain tumors including low-grade gliomas. The present article surveys the results obtained using L-[methyl-11C]Methionine (MET), that has been the ancestor of PET amino acid tracers and is still the most popular amino acid imaging modality in oncology, and stresses the important role that this diagnostic modality can play in the evaluation of brain tumors. However, the use of MET is restricted to PET centers with an in-house cyclotron and radiochemistry facility, because of the short half-life (20 min) of 11C. The promising results of MET have stimulated the development of 18F-labelled aminoacid tracers, particularly O-(2-18F-fluoeoethyl1)-L-tyrosine (FET), that has the same properties of MET and, thanks to the longer half-life of 18F (about 110 min), allows a distribution strategy from a production tracer site to user satellite PET centers. Considering a more widespread use of Amino acid PET, together with the recent development of integrated PET-MRI imaging systems, and the oncoming clinical validation of other interesting PET tracers, i.e. FMISO or 18F-FAZA for hypoxia imaging and FLT for tumor proliferation imaging, it can be reasonably expected that metabolic imaging

  8. Azapeptide analogues of the growth hormone releasing peptide 6 as cluster of differentiation 36 receptor ligands with reduced affinity for the growth hormone secretagogue receptor 1a.

    PubMed

    Proulx, Caroline; Picard, Émilie; Boeglin, Damien; Pohankova, Petra; Chemtob, Sylvain; Ong, Huy; Lubell, William D

    2012-07-26

    The synthetic hexapeptide growth hormone releasing peptide-6 (GHRP-6) exhibits dual affinity for the growth hormone secretagogue receptor 1a (GHS-R1a) and the cluster of differentiation 36 (CD36) receptor. Azapeptide GHRP-6 analogues have been synthesized, exhibiting micromolar affinity to the CD36 receptor with reduced affinity toward the GHS-R1a. A combinatorial split-and-mix approach furnished aza-GHRP-6 leads, which were further examined by alanine scanning. Incorporation of an aza-amino acid residue respectively at the D-Trp(2), Ala(3), or Trp(4) position gave aza-GHRP-6 analogues with reduced affinity toward the GHS-R1a by at least a factor of 100 and in certain cases retained affinity for the CD36 receptor. In the latter cases, the D-Trp(2) residue proved important for CD36 receptor affinity; however, His(1) could be replaced by Ala(1) without considerable loss of binding. In a microvascular sprouting assay using a choroid explant, [azaTyr(4)]-GHRP-6 (15), [Ala(1), azaPhe(2)]-GHRP-6 (16), and [azaLeu(3), Ala(6)]-GHRP-6 (33) all exhibited antiangiogenic activity.

  9. Synthesis and pharmacology of halogenated δ-opioid-selective [d-Ala(2)]deltorphin II peptide analogues.

    PubMed

    Pescatore, Robyn; Marrone, Gina F; Sedberry, Seth; Vinton, Daniel; Finkelstein, Netanel; Katlowitz, Yitzchak E; Pasternak, Gavril W; Wilson, Krista R; Majumdar, Susruta

    2015-06-17

    Deltorphins are naturally occurring peptides produced by the skin of the giant monkey frog (Phyllomedusa bicolor). They are δ-opioid receptor-selective agonists. Herein, we report the design and synthesis of a peptide, Tyr-d-Ala-(pI)Phe-Glu-Ile-Ile-Gly-NH2 3 (GATE3-8), based on the [d-Ala(2)]deltorphin II template, which is δ-selective in in vitro radioligand binding assays over the μ- and κ-opioid receptors. It is a full agonist in [(35)S]GTPγS functional assays and analgesic when administered supraspinally to mice. Analgesia of 3 (GATE3-8) is blocked by the selective δ receptor antagonist naltrindole, indicating that the analgesic action of 3 is mediated by the δ-opioid receptor. We have established a radioligand in which (125)I is incorporated into 3 (GATE3-8). The radioligand has a KD of 0.1 nM in Chinese hamster ovary (CHO) cells expressing the δ receptor. Additionally, a series of peptides based on 3 (GATE3-8) was synthesized by incorporating various halogens in the para position on the aromatic ring of Phe(3). The peptides were characterized for binding affinity at the μ-, δ-, and κ-opioid receptors, which showed a linear correlation between binding affinity and the size of the halogen substituent. These peptides may be interesting tools for probing δ-opioid receptor pharmacology.

  10. Bioorthogonal chemistry for (68) Ga radiolabelling of DOTA-containing compounds.

    PubMed

    Evans, Helen L; Carroll, Laurence; Aboagye, Eric O; Spivey, Alan C

    2014-04-01

    Copper-catalysed 'click' chemistry is a highly utilised technique for radiolabelling small molecules and peptides for imaging applications. The usefulness of these reactions falls short, however, when metal catalysis is not a practically viable route; such as when using metal chelates as radioligands. Here, we describe a method for carrying out 'click-type' radiochemistry in the presence of DOTA chelates, by combining (68) Ga radiolabelling techniques with well-established bioorthogonal reactions, which do not rely upon metal catalysis.

  11. Acute effects of the glucagon-like peptide 2 analogue, teduglutide, on intestinal adaptation in short bowel syndrome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Neonatal short bowel syndrome following massive gut resection is associated with malabsorption of nutrients. The intestinotrophic factor glucagon-like peptide 2 (GLP-2) improves gut function in adult patients with short bowel syndrome, but its effect in pediatric patients remains unknown. Our object...

  12. Influence of the Charge State on the Structures and Interactions of Vancomycin Antibiotics with Cell-Wall Analogue Peptides: Experimental and Theoretical Studies

    SciTech Connect

    Yang, Zhibo; Vorpagel, Erich R.; Laskin, Julia

    2009-02-16

    In this study we examined the effect of the charge state on the energetics and dynamics of dissociation of the non-covalent complex between the vancomycin and the cell wall peptide analogue Nα,Nε-diacetyl-L-Lys-D-Ala-D-Ala (V-Ac2KDADA). The binding energies between the vancomycin and the peptide were obtained from the RRKM modeling of the time- and energy resolved surface-induced dissociation (SID) experiments. Our results demonstrate that the stability of the complex toward fragmentation increases in the order: [V+Ac2KDADA+H]+2 < [V+Ac2KDADA+H]+ < [V+Ac2KDADA-H]-. Dissociation of the singly protonated and singly deprotonated complex is characterized by very large entropy effects indicating substantial increase in the conformational flexibility of the resulting products. The experimental threshold energies of 1.75 eV and 1.34 eV obtained for the [V+Ac2KDADA-H]- and [V+Ac2KDADA+H]+ , respectively, are in excellent agreement with the results of density functional theory (DFT) calculations. The increased stability of the deprotonated complex observed experimentally is attributed to the presence of three charged sites in the deprotonated complex as compared to only one charged site in the singly protonated complex. The low binding energy of 0.93 eV obtained for the doubly protonated complex suggests that this ion is destabilized by Coulomb repulsion between the singly protonated vancomycin and the singly protonated peptide comprising the complex.

  13. Positron Emission Tomography Imaging Using Radiolabeled Inorganic Nanomaterials

    PubMed Central

    Sun, Xiaolian; Cai, Weibo; Chen, Xiaoyuan

    2015-01-01

    CONSPECTUS Positron emission tomography (PET) is a radionuclide imaging technology that plays an important role in preclinical and clinical research. With administration of a small amount of radiotracer, PET imaging can provide a noninvasive, highly sensitive, and quantitative readout of its organ/tissue targeting efficiency and pharmacokinetics. Various radiotracers have been designed to target specific molecular events. Compared with antibodies, proteins, peptides, and other biologically relevant molecules, nanoparticles represent a new frontier in molecular imaging probe design, enabling the attachment of different imaging modalities, targeting ligands, and therapeutic payloads in a single vector. We introduce the radiolabeled nanoparticle platforms that we and others have developed. Due to the fundamental differences in the various nanoparticles and radioisotopes, most radiolabeling methods are designed case-by-case. We focus on some general rules about selecting appropriate isotopes for given types of nanoparticles, as well as adjusting the labeling strategies according to specific applications. We classified these radiolabeling methods into four categories: (1) complexation reaction of radiometal ions with chelators via coordination chemistry; (2) direct bombardment of nanoparticles via hadronic projectiles; (3) synthesis of nanoparticles using a mixture of radioactive and nonradioactive precursors; (4) chelator-free postsynthetic radiolabeling. Method 1 is generally applicable to different nanomaterials as long as the surface chemistry is well-designed. However, the addition of chelators brings concerns of possible changes to the physicochemical properties of nanomaterials and detachment of the radiometal. Methods 2 and 3 have improved radiochemical stability. The applications are, however, limited by the possible damage to the nanocomponent caused by the proton beams (method 2) and harsh synthetic conditions (method 3). Method 4 is still in its infancy

  14. Positron emission tomography imaging using radiolabeled inorganic nanomaterials.

    PubMed

    Sun, Xiaolian; Cai, Weibo; Chen, Xiaoyuan

    2015-02-17

    CONSPECTUS: Positron emission tomography (PET) is a radionuclide imaging technology that plays an important role in preclinical and clinical research. With administration of a small amount of radiotracer, PET imaging can provide a noninvasive, highly sensitive, and quantitative readout of its organ/tissue targeting efficiency and pharmacokinetics. Various radiotracers have been designed to target specific molecular events. Compared with antibodies, proteins, peptides, and other biologically relevant molecules, nanoparticles represent a new frontier in molecular imaging probe design, enabling the attachment of different imaging modalities, targeting ligands, and therapeutic payloads in a single vector. We introduce the radiolabeled nanoparticle platforms that we and others have developed. Due to the fundamental differences in the various nanoparticles and radioisotopes, most radiolabeling methods are designed case-by-case. We focus on some general rules about selecting appropriate isotopes for given types of nanoparticles, as well as adjusting the labeling strategies according to specific applications. We classified these radiolabeling methods into four categories: (1) complexation reaction of radiometal ions with chelators via coordination chemistry; (2) direct bombardment of nanoparticles via hadronic projectiles; (3) synthesis of nanoparticles using a mixture of radioactive and nonradioactive precursors; (4) chelator-free postsynthetic radiolabeling. Method 1 is generally applicable to different nanomaterials as long as the surface chemistry is well-designed. However, the addition of chelators brings concerns of possible changes to the physicochemical properties of nanomaterials and detachment of the radiometal. Methods 2 and 3 have improved radiochemical stability. The applications are, however, limited by the possible damage to the nanocomponent caused by the proton beams (method 2) and harsh synthetic conditions (method 3). Method 4 is still in its infancy

  15. Slowly on, Slowly off: Bisubstrate-Analogue Conjugates of 5-Iodotubercidin and Histone H3 Peptide Targeting Protein Kinase Haspin.

    PubMed

    Kestav, Katrin; Viht, Kaido; Konovalov, Anton; Enkvist, Erki; Uri, Asko; Lavogina, Darja

    2017-02-09

    The atypical protein kinase Haspin serves as one of a key players in mitosis by catalysing phosphorylation of Thr3 in histone H3, and thus sustaining the normal functioning of the chromosomal passenger complex. Here, we report the development of bisubstrate-analogue inhibitors targeting Haspin. The compounds were constructed by linking 5-iodotubercidin moiety to the N-terminal sequence of histone H3. The new conjugates possessed high affinity (KD in the subnanomolar range) towards Haspin as well as slow kinetics of association and dissociation (residence time on the scale of several hours), which reflected their unique binding mode and translated into improved selectivity. The latter was confirmed in a biochemical binding/displacement assay with a panel of 10 protein kinases, in thermal shift assay with off-targets of 5-iodotubercidin represented by adenosine kinase and the Cdc2-like kinase family, as well as in assay with spiked lysates of HeLa cells.

  16. Lutetium-177 Labeled Peptides: The European Institute of Oncology Experience.

    PubMed

    Carollo, Angela; Papi, Stefano; Chinol, Marco

    2016-01-01

    Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogues has shown encouraging results in various somatostatin receptor positive tumors. Partial remission rates up to 30% have been documented as well as significant improvements in quality of life and survival. This treatment takes advantage of the high specific binding of the radiolabeled peptide to somatostatin receptors overexpressed by the tumors thus being more effective on the tumor cells with less systemic side-effects. The development of macrocyclic chelators conjugated to peptides made possible the stable binding with various radionuclides. In particular 177Lu features favourable physical characteristics with a half-life of 6.7 days, emission of β- with energy of 0.5 MeV for treatment and γ-emissions suitable for imaging. The present contribution describes the learning process achieved at the European Institute of Oncology (IEO) since the first application of 90Y labeled peptides to the therapy of neuroendocrine tumors back in 1997. Continuous improvements led to the preparation of a safe 177Lu labeled peptide for human use. Our learning curve began with the identification of the optimal characteristics of the isotope paying attention to its chemical purity and specific activity along with the optimization of the parameters involved in the radiolabeling procedure. Also the radiation protection issues have been improved along the years and recently more and more attention has been devoted to the pharmaceutical aspects involved in the preparation. The overall issue of the quality has now been completed by drafting an extensive documentation with the goal to deliver a safe and reliable product to our patients.

  17. Reducing renal uptake of 90Y- and 177Lu-labeled alpha-melanocyte stimulating hormone peptide analogues

    SciTech Connect

    Miao, Yubin; Fisher, Darrell R.; Quinn, Thomas P.

    2006-06-15

    The purpose of this study was to improve the tumor-to-kidney uptake ratios of 90Y- and 177Lu-[1,2,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-Re-Cys,D-Phe,Arg]alpha-melanocyte stimulating hormone (DOTA-RE(Arg)CCMSH), through coupling a negatively charged glutamic acid (Glu) to the peptide sequence. A new peptide of DOTA-Re(Glu,Arg)CCMSH was designed, synthesized and labeled with 90Y and 177Lu. Pharmacokinetics of 90Y- and 177Lu-DOTA-RE(Glu,Arg)CCNSH were determined in B16/F1 murine melanoma-bearing C57 mice. Both exhibited significantly less renal uptake than 90Y- and 177Lu-DOTA-Re(Arg)CCMSH at 30 min and at 2, 3, and 24 h after dose administration. The renal uptake values of 90Y- and 177Lu-DOTA-Re(Glu,Arg)CCMSH were 28.16% and 28.81% of those of 90Y- and 177Lu-DOTA-RE(Arg)CCMSH, respectively, at 4 hr post-injection. We also showed higher tumor-to-kidney uptake ratios 2.28 and 1.69 times that of 90Y- and 177Lu-DOTA-Re(Arg)CCMSH, respectively, at 4 h post-injection. The90Y- and 177Lu-DOTA-Re(Glu,Arg)CCMSH activity accumulation was low in normal organs except for kidneys. Coupling a negatively charged amino acid (Glu) to the CCMSH peptide sequence dramatically reduced the renal uptake values and increased the tumor-to-kidney uptake ratios of 90Y- and 177Lu-DOTA-Re(Glu,Arg)CCMSH, facilitating their potential applications as radiopharmaceuticals for targeted radionuclide therapy of melanoma.

  18. The Effect of the Secondary Structure on Dissociation of Peptide Radical Cations: Fragmentation of Angiotensin III and Its Analogues

    SciTech Connect

    Yang, Zhibo; Lam, Corey; Chu, Ivan K.; Laskin, Julia

    2008-09-28

    Fragmentation of protonated RVYIHPF and RVYIHPF-OMe and the corresponding radical cations was studied using time- and collision energy-resolved surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) specially equipped to perform SID experiments. Peptide radical cations were produced by gas-phase fragmentation of CoIII(salen)-peptide complexes. Both the energetics and mechanisms of dissociation of even-electron and odd-electron angiotensin III ions are quite different. Protonated molecules are much more stable towards fragmentation than the corresponding radical cations. RRKM modeling of the experimental data suggests that this stability is largely attributed to differences in threshold energies for dissociation while activation entropies are very similar. Detailed analysis of the experimental data obtained for radical cations demonstrated the presence of two distinct structures separated by a high free-energy barrier. The two families of structures were ascribed to the canonical and zwitterionic forms of the radical cations produced in our experiments.

  19. An analogue of atrial natriuretic peptide (C-ANP4-23) modulates glucose metabolism in human differentiated adipocytes.

    PubMed

    Ruiz-Ojeda, Francisco Javier; Aguilera, Concepción María; Rupérez, Azahara Iris; Gil, Ángel; Gomez-Llorente, Carolina

    2016-08-15

    The present study was undertaken to investigate the effects of C-atrial natriuretic peptide (C-ANP4-23) in human adipose-derived stem cells differentiated into adipocytes over 10 days (1 μM for 4 h). The intracellular cAMP, cGMP and protein kinase A levels were determined by ELISA and gene and protein expression were determined by qRT-PCR and Western blot, respectively, in the presence or absence of C-ANP4-23. The levels of lipolysis and glucose uptake were also determined. C-ANP4-23 treatment significantly increased the intracellular cAMP levels and the gene expression of glucose transporter type 4 (GLUT4) and protein kinase, AMP-activated, alpha 1 catalytic subunit (AMPK). Western blot showed a significant increase in GLUT4 and phosphor-AMPKα levels. Importantly, the adenylate cyclase inhibitor SQ22536 abolished these effects. Additionally, C-ANP4-23 increased glucose uptake by 2-fold. Our results show that C-ANP4-23 enhances glucose metabolism and might contribute to the development of new peptide-based therapies for metabolic diseases.

  20. Structural and Dynamic Insights into a Glycine-Mediated Short Analogue of a Designed Peptide in Lipopolysaccharide Micelles: Correlation Between Compact Structure and Anti-Endotoxin Activity.

    PubMed

    Datta, Aritreyee; Jaiswal, Nancy; Ilyas, Humaira; Debnath, Shibjyoti; Biswas, Kaushik; Kumar, Dinesh; Bhunia, Anirban

    2017-02-21

    In this study, we report an interaction study of a 13-residue analogue peptide VG13P (VARGWGRKCPLFG), derived from a designed VG16KRKP peptide (VARGWKRKCPLFGKGG), with a Lys6Gly mutation and removal of the last three residues Lys(14)-Gly(15)-Gly(16), in lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria and responsible for sepsis or septic shock. VG13P displays an enhanced anti-endotoxin property as evident from significant reduction in LPS-induced TNF-α gene expression levels in a monocytic cell line, while it retains almost unchanged antimicrobial activity as its parent VG16KRKP against Gram-negative bacterial as well as fungal pathogens. In addition, in vitro LPS binding properties of VG13P in comparison to its parent VG16KRKP also remained unhindered, suggesting that the flexible C-terminal end of VG16KRKP may not play a major role in its observed antibacterial and LPS binding properties. An NMR-resolved solution structure of VG13P in LPS reveals two consecutive β-turns: one at the N-terminus, followed by another at the central region, closely resembling a rocking chair. The crucial Lys6Gly mutation along with C-terminal truncation from VG16KRKP reorients the hydrophobic hub in VG13P in a unique way so as to fold the N-terminal end back on itself, forming a turn and allowing Val1 and Ala2 to interact with Leu11 and Phe12 to bring the hydrophobic residues closer together to form a more compact hub compared to its parent. The hub is further strengthened via CH-π interaction between Gly4 and Phe12. This accounts for its improved anti-endotoxin activity as well as to its uninterrupted antimicrobial activity.

  1. Vector-Mediated Delivery of a Polyamide ("Peptide") Nucleic Acid Analogue through the Blood-Brain Barrier in vivo

    NASA Astrophysics Data System (ADS)

    Pardridge, William M.; Boado, Ruben J.; Kang, Young-Sook

    1995-06-01

    Polyamide ("peptide") nucleic acids (PNAs) are molecules with antigene and antisense effects that may prove to be effective neuropharmaceuticals if these molecules are enabled to undergo transport through the brain capillary endothelial wall, which makes up the blood-brain barrier in vivo. The model PNA used in the present studies is an 18-mer that is antisense to the rev gene of human immunodeficiency virus type 1 and is biotinylated at the amino terminus and iodinated at a tyrosine residue near the carboxyl terminus. The biotinylated PNA was linked to a conjugate of streptavidin (SA) and the OX26 murine monoclonal antibody to the rat transferrin receptor. The blood-brain barrier is endowed with high transferrin receptor concentrations, enabling the OX26-SA conjugate to deliver the biotinylated PNA to the brain. Although the brain uptake of the free PNA was negligible following intravenous administration, the brain uptake of the PNA was increased at least 28-fold when the PNA was bound to the OX26-SA vector. The brain uptake of the PNA bound to the OX26-SA vector was 0.1% of the injected dose per gram of brain at 60 min after an intravenous injection, approximating the brain uptake of intravenously injected morphine. The PNA bound to the OX26-SA vector retained the ability to bind to synthetic rev mRNA as shown by RNase protection assays. In summary, the present studies show that while the transport of PNAs across the blood-brain barrier is negligible, delivery of these potential neuropharmaceutical drugs to the brain may be achieved by coupling them to vector-mediated peptide-drug delivery systems.

  2. Novel GLP-1 (Glucagon-Like Peptide-1) Analogues and Insulin in the Treatment for Alzheimer's Disease and Other Neurodegenerative Diseases.

    PubMed

    Calsolaro, Valeria; Edison, Paul

    2015-12-01

    The link between diabetes mellitus and Alzheimer's disease (AD) has been known for the last few decades. Since insulin and insulin receptors are known to be present in the brain, the downstream signalling as well as the effect of hyperinsulinemia have been extensively studied in both AD and Parkinson's disease. Glucagon-like peptide-1 (GLP-1) is a hormone belonging to the incretin family, and its receptors (GLP-1Rs) can be found in pancreatic cells and in vascular endothelium. Interestingly, GLP-1Rs are found in the neuronal cell body and dendrites in the central nervous system (CNS), in particular in the hypothalamus, hippocampus, cerebral cortex and olfactory bulb. Several studies have shown the importance of both insulin and GLP-1 signalling on cognitive function, and many preclinical studies have been performed to evaluate the potential protective role of GLP-1 on the brain. Here we review the underlying mechanism of insulin and GLP-1 signalling in the CNS, as well as the preclinical data for the use of GLP-1 analogues such as liraglutide, exenatide and lixisenatide in neurodegenerative diseases.

  3. Clinical uses of radiolabeled platelets

    SciTech Connect

    Datz, F.L.; Christian, P.E.; Baker, W.J.

    1985-12-01

    Platelets were first successfully radiolabeled in 1953. At that time, investigators were primarily interested in developing a technique to accurately measure platelet life span in both normal and thrombocytopenic patients. Studies using platelets labeled with /sup 51/Cr have shown shortened platelet survival times in a number of diseases including idiopathic thrombocytopenic purpura, coronary artery disease, and diabetes mellitus. More recently, labels such as /sup 111/In have been developed that allow in vivo imaging of platelets. Indium-111 platelets are being used to better understand the pathophysiology of atherosclerosis, thrombophlebitis, pulmonary embolism and clotting disorders, and to improve the clinical diagnosis of these diseases.

  4. Design of a Photoreactive Analogue of the Escherichia coli Heat-Stable Enterotoxin STIb: Use in Identifying Its Receptor on Rat Brush Border Membranes

    NASA Astrophysics Data System (ADS)

    Gariepy, Jean; Schoolnik, Gary K.

    1986-01-01

    The Escherichia coli heat-stable enterotoxin, STIb was prepared by solid-phase peptide synthesis and purified to homogeneity by high-pressure liquid chromatography. This analogue was iodinated and shown to bind specifically to rat intestinal membranes. The radiolabeled peptide was derivatized at the amino terminus with the photoreactive heterobifunctional crosslinking agent N-hydroxysuccinimidyl p-benzoylbenzoate. This photoreactive probe also exhibited binding specificity. It was mixed with rat intestinal brush border membranes and photolyzed in the presence or absence of excess unlabeled STIb. Polyacrylamide gel electrophoresis performed in the presence of sodium dodecyl sulfate and 2-mercaptoethanol indicated that the peptide probe was cross-linked specifically to two molecular species of 57 and 75 kDa. One or both of these molecules appear to constitute the enterotoxin receptor or to be in close proximity to it.

  5. Targeted Radiolabeled Compounds in Glioma Therapy.

    PubMed

    Cordier, Dominik; Krolicki, Leszek; Morgenstern, Alfred; Merlo, Adrian

    2016-05-01

    Malignant gliomas of World Health Organization (WHO) grades II-IV represent the largest entity within the group of intrinsic brain tumors and are graded according to their pathophysiological features with survival times between more than 10 years (WHO II) and only several months (WHO IV). Gliomas arise from astrocytic or oligodendrocytic precursor cells and exhibit an infiltrative growth pattern lacking a clearly identifiable tumor border. The development of effective treatment strategies of the invasive tumor cell front represents the main challenge in glioma therapy. The therapeutic standard consists of surgical resection and, depending on the extent of resection and WHO grade, adjuvant external beam radiotherapy or systemic chemotherapy. Within the last decades, there has been no major improvement of the prognosis of patients with glioma. The consistent overexpression of neurokinin type 1 receptors in gliomas WHO grades II-IV has been used to develop a therapeutic substance P-based targeting system. A substance P-analogue conjugated to the DOTA or DOTAGA chelator has been labeled with different alpha-particle or beta-particle emitting radionuclides for targeted glioma therapy. The radiopharmaceutical has been locally injected into the tumors or the resection cavity. In several clinical studies, the methodology has been examined in adjuvant and neoadjuvant clinical settings. Although no large controlled series have so far been generated, the results of radiolabeled substance P-based targeted glioma therapy compare favorably with standard therapy. Recently, labeling with the alpha particle emitting Bi-213 has been found to be promising due to the high linear energy transfer and the very short tissue range of 0.08 mm. Further development needs to focus on the improvement of the stability of the compound and the application by dedicated catheter systems to improve the intratumoral distribution of the radiopharmaceutical within the prognostically critical

  6. Teduglutide, a glucagon-like peptide 2 analogue: a novel protective agent with anti-apoptotic and anti-oxidant properties in mice with lung injury.

    PubMed

    Arda-Pirincci, Pelin; Oztay, Fusun; Bayrak, Bertan Boran; Yanardag, Refiye; Bolkent, Sehnaz

    2012-12-01

    Teduglutide is a long-acting synthetic analogue of human glucagon-like peptide-2 (GLP-2). GLP-2 regulates cell proliferation and apoptosis as well as normal physiology in the gastrointestinal tract. In the present study, possible cytoprotective and reparative effects of teduglutide were analyzed on a mouse model with lung injury induced by tumor necrosis factor-alpha (TNF-α) and actinomycin D (Act D). BALB/c mice were divided into six groups: control mice (I), mice injected intraperitoneally with 15 μg/kg TNF-α (II), 800 μg/kg Act D (III), Act D 2 min prior to TNF-α administration with the same doses (IV), mice injected subcutaneously with 200 μg/kg teduglutide every 12h for 10 consecutive days (V), and mice given Act D 2 min prior to TNF-α administration on day 11 after receiving teduglutide for 10 days (VI). The TNF-α/Act D administration made the lung a sensitive organ to damage. Mice lung subjected to TNF-α/Act D were characterized by the disruption of alveolar wall, induced pulmonary endothelial/epithelial cell apoptosis and expression of active caspase-3. These mice exhibited an increase in lipid peroxidation, glutathione levels, and activities of myeloperoxidase, superoxide dismutase, catalase, glutathione peroxidase and xanthine oxidase, as well as reduced tissue factor and sodium-potassium/ATPase activities. Teduglutide pretreatment regressed the structural damage, cell apoptosis and oxidative stress by reducing lipid peroxidation in mice received TNF-α/Act D. GLP-2 receptors were present on the cell membrane of type II pneumocytes and interstitial cells. Thus, teduglutide can be suggested as a novel protective agent, which possesses anti-apoptotic and anti-oxidant properties, against lung injury.

  7. Intrinsically Radiolabeled Nanoparticles: An Emerging Paradigm

    PubMed Central

    Goel, Shreya; Ehlerding, Emily B.

    2014-01-01

    Although chelator-based radiolabeling techniques have been used for decades, concerns about the complexity of coordination chemistry, possible altering of pharmacokinetics of carriers, and potential detachment of radioisotopes during imaging have driven the need for developing a simple yet better technique for future radiolabeling. Here, the emerging concept of intrinsically radiolabeled nanoparticles, which could be synthesized using methods such as hot-plus-cold precursors, specific trapping, cation exchange, and proton beam activation, is introduced. Representative examples of using these multifunctional nanoparticles for multimodality molecular imaging are highlighted together with current challenges and future research directions. Although still in the early stages, design and synthesis of intrinsically radiolabeled nanoparticles has shown attractive potential to offer easier, faster, and more specific radiolabeling possibilities for the next generation of molecular imaging. PMID:24978934

  8. The future of somatostatin analogue therapy.

    PubMed

    Stewart, P M; James, R A

    1999-10-01

    Since its discovery almost 30 years ago, the mode of action and therapeutic applications of somatostatin have been defined. In particular the cloning and characterization of somatostatin receptor subtypes has facilitated the development of high affinity analogues. In the context of pituitary disease, long-acting somatostatin analogues (octreotide, lanreotide) have been used to treat a variety of pituitary tumours but are most efficacious for the treatment of GH and TSH-secreting adenomas. In patients with acromegaly, depot preparations of these analogues are administered intramuscularly every 10-28 days and provide consistent suppression of GH levels to < 5 mU/l in approximately 50-65% of all cases. Even more specific somatostatin receptor analogues are under development. Finally, radiolabelled somatostatin analogue scintigraphy and, in larger doses, therapy, are now established tools in the evaluation and treatment of neuroendocrine tumours.

  9. Recent developments in monoclonal antibody radiolabeling techniques

    SciTech Connect

    Srivastava, S.C.; Mease, R.C.

    1989-01-01

    Monoclonal antibodies (MAbs) have shown the potential to serve as selective carriers of radionuclides to specific in vivo antigens. Accordingly, there has been an intense surge of research activity in an effort to develop and evaluate MAb-based radiopharmaceuticals for tumor imaging (radioimmunoscintigraphy) and therapy (radioimmunotherapy), as well as for diagnosing nonmalignant diseases. A number of problems have recently been identified, related to the MAbs themselves and to radiolabeling techniques, that comprise both the selectivity and the specificity of the in vivo distribution of radiolabeled MAbs. This paper will address some of these issues and primarily discuss recent developments in the techniques for radiolabeling monoclonal antibodies that may help resolve problems related to the poor in vivo stability of the radiolabel and may thus produce improved biodistribution. Even though many issues are identical with therapeutic radionuclides, the discussion will focus mainly on radioimmunoscintigraphic labels. 78 refs., 6 tabs.

  10. Development of potent anti-infective agents from Silurana tropicalis: conformational analysis of the amphipathic, alpha-helical antimicrobial peptide XT-7 and its non-haemolytic analogue [G4K]XT-7.

    PubMed

    Subasinghage, Anusha P; Conlon, J Michael; Hewage, Chandralal M

    2010-04-01

    Peptide XT-7 (GLLGP(5)LLKIA(10)AKVGS(15)NLL.NH(2)) is a cationic, leucine-rich peptide, first isolated from skin secretions of the frog, Silurana tropicalis (Pipidae). The peptide shows potent, broad-spectrum antimicrobial activity but its therapeutic potential is limited by haemolytic activity (LC(50)=140 microM). The analogue [G4K]XT-7, however, retains potent antimicrobial activity but is non-haemolytic (LC(50)>500 microM). In order to elucidate the molecular basis for this difference in properties, the three dimensional structures of XT-7 and the analogue have been investigated by proton NMR spectroscopy and molecular modelling. In aqueous solution, both peptides lack secondary structure. In a 2,2,2-trifluoroethanol (TFE-d(3))-H(2)O mixed solvent system, XT-7 is characterised by a right handed alpha-helical conformation between residues Leu(3) and Leu(17) whereas [G4K]XT-7 adopts a more restricted alpha-helical conformation between residues Leu(6) and Leu(17). A similar conformation for XT-7 in 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) micellular media was observed with a helical segment between Leu(3) and Leu(17). However, differences in side chain orientations restricting the hydrophilic residues to a smaller patch resulted in an increased hydrophobic surface relative to the conformation in TFE-H(2)O. Molecular modelling of the structures obtained in our study demonstrates the amphipathic character of the helical segments. It is proposed that the marked decrease in haemolytic activity produced by the substitution Gly(4)-->Lys in XT-7 arises from a decrease in both helicity and hydrophobicity. These studies may facilitate the development of potent but non-toxic anti-infective agents based upon the structure of XT-7.

  11. Analogue Gravity.

    PubMed

    Barceló, Carlos; Liberati, Stefano; Visser, Matt

    2011-01-01

    Analogue gravity is a research programme which investigates analogues of general relativistic gravitational fields within other physical systems, typically but not exclusively condensed matter systems, with the aim of gaining new insights into their corresponding problems. Analogue models of (and for) gravity have a long and distinguished history dating back to the earliest years of general relativity. In this review article we will discuss the history, aims, results, and future prospects for the various analogue models. We start the discussion by presenting a particularly simple example of an analogue model, before exploring the rich history and complex tapestry of models discussed in the literature. The last decade in particular has seen a remarkable and sustained development of analogue gravity ideas, leading to some hundreds of published articles, a workshop, two books, and this review article. Future prospects for the analogue gravity programme also look promising, both on the experimental front (where technology is rapidly advancing) and on the theoretical front (where variants of analogue models can be used as a springboard for radical attacks on the problem of quantum gravity).

  12. Synthesis of a cyanopeptide-analogue with trypsin activating properties.

    PubMed

    Radau, G; Rauh, D

    2000-04-17

    An efficient synthesis of a peptidic analogue of cyanobacterial metabolites with proposed serine protease inhibitory activity has been developed. Surprisingly, one trypsin activating compound was obtained.

  13. [Radiolabeled antibodies for cancer treatment].

    PubMed

    Barbet, Jacques; Chatal, Jean-François; Kraeber-Bodéré, Françoise

    2009-12-01

    The first treatment ever by radio-immunotherapy (RIT) was performed by William H. Beierwaltes in 1951 and was a success. Fifty years later, the main question is to find ways of extending the success of radiolabelled anti-CD20 antibodies in indolent non-Hodgkin's lymphoma to other forms of cancer. Solid tumours are much more radioresistant than lymphomas, but they respond to RIT if the lesions are small. Clinical situations of residual or minimal disease are thus the most likely to benefit from RIT in the adjuvant or consolidation settings. For disseminated disease, like leukemias or myelomas, the problem is different: beta- particles emitted by the radioactive atoms classically used for cancer treatment (iodine-131 or yttrium-90) disperse their energy in large volumes (ranges 1 mm to 1 cm) and are not very effective against isolated cells. Advances in RIT progress in two directions. One is the development of pretargeting strategies in which the antibody is not labelled but used to provide binding sites to small molecular weight radioactivity vectors (biotin, haptens). These techniques have been shown to increase tumour to non-target uptake ratios and anti-tumour efficacy has been demonstrated in the clinic. The other approach is the use of radionuclides adapted to the various clinical situations. Lutetium-177 or copper-67, because of the lower energy of their emission, their relatively long half-life and good gamma emission, may significantly improve RIT efficacy and acceptability. Beyond that, radionuclides emitting particles such as alpha particles or Auger electrons, much more efficient to kill isolated tumour cells, are being tested for RIT in the clinic. Finally, RIT should be integrated with other cancer treatment approaches in multimodality protocols. Thus RIT, now a mature technology, should enter a phase of well designed and focused clinical developments that may be expected to afford significant therapeutic advances.

  14. Specific Anti-Leukemic Activity of the Peptide Warnericin RK and Analogues and Visualization of Their Effect on Cancer Cells by Chemical Raman Imaging

    PubMed Central

    Loiseau, Clémence; Augenstreich, Jacques; Marchand, Adrienne; Harté, Etienne; Garcia, Martine; Verdon, Julien; Mesnil, Marc; Lecomte, Sophie; Berjeaud, Jean-Marc

    2016-01-01

    Antimicrobial peptides can be used as therapeutic agents against cancer cells. Warnericin RK and derivatives (WarnG20D and WarnF14V) were tested on various, solid tumor or leukemia, cancer cells. These peptides appeared to be cytotoxic on all the cell types tested, cancerous as well healthy, but very interestingly displayed no deleterious effect on healthy mononuclear cells. The mode of action of the peptide was proposed to be membranolytic, using chemical Raman imaging. Addition of peptide induced a large disorganization of the membrane leading to the loss of the content of inner compartments of Jurkat cell, whereas no effect was observed on the healthy mononuclear cells. The less hemolytic peptides WarnG20D and WarnF14V could be good candidates for the leukemia treatment. PMID:27598770

  15. Radiolabeled Nanoparticles for Multimodality Tumor Imaging

    PubMed Central

    Xing, Yan; Zhao, Jinhua; Conti, Peter S.; Chen, Kai

    2014-01-01

    Each imaging modality has its own unique strengths. Multimodality imaging, taking advantages of strengths from two or more imaging modalities, can provide overall structural, functional, and molecular information, offering the prospect of improved diagnostic and therapeutic monitoring abilities. The devices of molecular imaging with multimodality and multifunction are of great value for cancer diagnosis and treatment, and greatly accelerate the development of radionuclide-based multimodal molecular imaging. Radiolabeled nanoparticles bearing intrinsic properties have gained great interest in multimodality tumor imaging over the past decade. Significant breakthrough has been made toward the development of various radiolabeled nanoparticles, which can be used as novel cancer diagnostic tools in multimodality imaging systems. It is expected that quantitative multimodality imaging with multifunctional radiolabeled nanoparticles will afford accurate and precise assessment of biological signatures in cancer in a real-time manner and thus, pave the path towards personalized cancer medicine. This review addresses advantages and challenges in developing multimodality imaging probes by using different types of nanoparticles, and summarizes the recent advances in the applications of radiolabeled nanoparticles for multimodal imaging of tumor. The key issues involved in the translation of radiolabeled nanoparticles to the clinic are also discussed. PMID:24505237

  16. Galleria mellonella native and analogue peptides Gm1 and ΔGm1. II) anti-bacterial and anti-endotoxic effects.

    PubMed

    Correa, Wilmar; Manrique-Moreno, Marcela; Behrends, Jochen; Patiño, Edwin; Marella, Chakravarthy; Peláez-Jaramillo, Carlos; Garidel, Patrick; Gutsmann, Thomas; Brandenburg, Klaus; Heinbockel, Lena

    2014-10-01

    Antimicrobial peptides (AMPs) are important components of the innate immune system of animals, plants, fungi and bacteria and are recently under discussion as promising alternatives to conventional antibiotics. We have investigated two cecropin-like synthetic peptides, Gm1, which corresponds to the natural overall uncharged Galleria mellonella native peptide and ΔGm1, a modified overall positively charged Gm1 variant. We have analysed these peptides for their potential to inhibit the endotoxin-induced secretion of tumour necrosis factor-α (TNF-α) from human mononuclear cells. Furthermore, in a conventional microbiological assay, the ability of these peptides to inhibit the growth of the rough mutant bacteria Salmonella enterica Minnesota R60 and the polymyxin B-resistant Proteus mirabilis R45 was investigated and atomic force microscopy (AFM) measurements were performed to characterize the morphology of the bacteria treated by the two peptides. We have also studied their cytotoxic properties in a haemolysis assay to clarify potential toxic effects. Our data revealed for both peptides minor anti-inflammatory (anti-endotoxin) activity, but demonstrated antimicrobial activity with differences depending on the endotoxin composition of the respective bacteria. In accordance with the antimicrobial assay, AFM data revealed a stronger morphology change of the R45 bacteria than for the R60. Furthermore, Gm1 had a stronger effect on the bacteria than ΔGm1, leading to a different morphology regarding indentations and coalescing of bacterial structures. The findings verify the biophysical measurements with the peptides on model systems. Both peptides lack any haemolytic activity up to an amount of 100μg/ml, making them suitable as new anti-infective agents.

  17. Galleria mellonella native and analogue peptides Gm1 and ΔGm1. I) biophysical characterization of the interaction mechanisms with bacterial model membranes.

    PubMed

    Correa, Wilmar; Manrique-Moreno, Marcela; Patiño, Edwin; Peláez-Jaramillo, Carlos; Kaconis, Yani; Gutsmann, Thomas; Garidel, Patrick; Heinbockel, Lena; Brandenburg, Klaus

    2014-10-01

    Natural occurring antimicrobial peptides (AMPs) are important components of the innate immune system of animals and plants. They are considered to be promising alternatives to conventional antibiotics. Here we present a comparative study of two synthetic peptides: Gm1, corresponding to the natural overall uncharged peptide from Galleria mellonella (Gm) and ΔGm1, a modified overall positively charged Gm1 variant. We have studied the interaction of the peptides with lipid membranes composed of different kinds of lipopolysaccharides (LPS) and dimyristoylphosphatidylglycerol (DMPG), in some cases also dimyristoylphosphatidylethanolamine (DMPE) as representative lipid components of Gram-negative bacterial membranes, by applying Fourier-transform infrared spectroscopy (FTIR), Förster resonance energy transfer spectroscopy (FRET), differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC). Gm1 generates a destabilizing effect on the gel to liquid crystalline phase transition of the acyl chains of the lipids, as deduced from a decrease in the phase transition temperature and enthalpy, suggesting a fluidization, whereas ΔGm1 led to the opposite behavior. Further, FTIR analysis of the functional groups of the lipids participating in the interaction with the peptides indicated a shift in the band position and intensity of the asymmetric PO2(-) stretching vibration originating from the lipid phosphate groups, a consequence of the sterical changes in the head group region. Interestingly, FRET spectroscopy showed a similar intercalation of both peptides into the DMPG and LPS, but much less into the DMPE membrane systems. These results are discussed in the light of a possible use of the peptides as antimicrobial and anti-endotoxin drugs.

  18. Oral peptide delivery by tetraether lipid liposomes.

    PubMed

    Parmentier, Johannes; Thewes, Bernhard; Gropp, Felix; Fricker, Gert

    2011-08-30

    The aim of this study is to improve of oral peptide delivery by a novel type of liposomes containing tetraether lipids (TELs) derived from archaea bacteria. Liposomes were used for the oral delivery of the somatostatin analogue octreotide. TELs were extracted from Sulfolobus acidocaldarius and subsequently purified to single compounds. Liposomes were prepared by the film method followed by extrusion. Vesicles in size between 130 and 207 nm were obtained as confirmed by photon correlation spectroscopy. The pharmacokinetics of radiolabeled TELs in liposomes was investigated after oral administration to rats. 1.6% of the applied radioactivity in fed and 1.5% in fasted rats was recovered in the blood and inner organs after 2h, while most of the radioactivity remained in the gastro-intestinal tract. After 24h the percentage of radioactivity in inner organs was reduced to 0.6% in fed rats, respectively 1.0% in fasted animals. Several liposomal formulations containing dipalmitoyl phosphatidylcholine (DPPC) and TELs in different ratios were loaded with octreotide and orally administered. Liposomes with 25% TEL could improve the oral bioavailability of octreotide 4.1-fold and one formulation with a cationic TEL derivative 4.6-fold. TEL-liposomes probably act by protecting the peptide in the gastro-intestinal tract.

  19. Generation and characterization of radiolabeled diesel exhaust.

    PubMed

    Dutcher, J S; Sun, J D; Lopez, J A; Wolf, I; Wolff, R K; McClellan, R O

    1984-07-01

    To evaluate the potential health risks associated with increased use of diesel engines, information is needed on the biological fate of inhaled diesel exhaust components. Appropriately radiolabeled exhaust produced by burning radiolabeled fuel could be used to gain this information. The purpose of this study was to characterize different radiolabeled diesel exhausts with respect to their potential use in studies of the biological fate of exhaust carbon particles and particle-associated organic compounds (particle extracts). A single-cylinder diesel engine was used to burn diesel fuel containing trace amounts of 14C-labeled hexadecane, dotriacontane, benzene, phenanthrene or benzo(a)pyrene. Greater than 98% of the 14C in all additives was converted to volatile materials upon combustion. The remainder was distributed in varying amounts between the carbon particles and particle extracts. Aromatic additives labeled carbon particles more efficiently than aliphatic additives. Column chromatography of the particle extracts showed that, in most cases, the majority of the radioactivity eluted in fractions identical to the specific fuel additive employed, suggesting that a large amount of the particle-associated organic compounds consisted of uncombusted fuel constituents. Applying an electrical load to the engine-electrical generator increased carbon particle radioactivity, but had variable effects on the amount of radioactivity in the particle extracts. 67Ga-tetramethylheptanedione was also studied as a fuel additive to label carbon particles. 67Ga was incorporated into the exhaust particles and lung deposition of particles in rats was found to be approximately 10%. However, the 67Ga-radiolabel was found to separate from the particles in vivo, making it an unsuitable radiolabel for studying the long-term lung retention of diesel exhaust carbonaceous particles.

  20. Substrate analogues for isoprenoid enzymes

    SciTech Connect

    Stremler, K.E.

    1987-01-01

    Diphosphonate analogues of geranyl diphosphate, resistant to degradation by phosphatases, were found to be alternate substrates for the reaction with farnesyl diphosphate synthetase isolated from avian liver. The difluoromethane analogue was shown to be the better alternate substrate, in agreement with solvolysis results which indicate that the electronegativity of the difluoromethylene unit more closely approximates that of the normal bridging oxygen. The usefulness of the C/sub 10/ difluoro analogue, for detecting low levels of isoprenoid enzymes in the presence of high levels of phosphatase activity, was demonstrated with a cell-free preparation from lemon peel. A series of C/sub 5/ through C/sub 15/ homoallylic and allylic diphosphonates, as well as two 5'-nucleotide diphosphonates, was prepared in high overall yield using the activation-displacement sequence. Radiolabeled samples of several of the allylic diphosphonates were prepared with tritium located at C1. A series of geraniols, stereospecifically deuterated at C1, was prepared. The enantiomeric purities and absolute configurations were determined by derivatization as the mandelate esters for analysis by /sup 1/H NMR. The stereochemistry of the activation-displacement sequence was examined using C1-deuterated substrates.

  1. Molecular structure of the rat vitamin D receptor ligand binding domain complexed with 2-carbon-substituted vitamin D3 hormone analogues and a LXXLL-containing coactivator peptide.

    PubMed

    Vanhooke, Janeen L; Benning, Matthew M; Bauer, Cary B; Pike, J Wesley; DeLuca, Hector F

    2004-04-13

    We have determined the crystal structures of the ligand binding domain (LBD) of the rat vitamin D receptor in ternary complexes with a synthetic LXXLL-containing peptide and the following four ligands: 1alpha,25-dihydroxyvitamin D(3); 2-methylene-19-nor-(20S)-1alpha,25-dihydroxyvitamin D(3) (2MD); 1alpha-hydroxy-2-methylene-19-nor-(20S)-bishomopregnacalciferol (2MbisP), and 2alpha-methyl-19-nor-1alpha,25-dihydroxyvitamin D(3) (2AM20R). The conformation of the LBD is identical in each complex. Binding of the 2-carbon-modified analogues does not change the positions of the amino acids in the ligand binding site and has no effect on the interactions in the coactivator binding pocket. The CD ring of the superpotent analogue, 2MD, is tilted within the binding site relative to the other ligands in this study and to (20S)-1alpha,25-dihydroxyvitamin D(3) [Tocchini-Valentini et al. (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 5491-5496]. The aliphatic side chain of 2MD follows a different path within the binding site; nevertheless, the 25-hydroxyl group at the end of the chain occupies the same position as that of the natural ligand, and the hydrogen bonds with histidines 301 and 393 are maintained. 2MbisP binds to the receptor despite the absence of the 25-hydroxyl group. A water molecule is observed between His 301 and His 393 in this structure, and it preserves the orientation of the histidines in the binding site. Although the alpha-chair conformer is highly favored in solution for the A ring of 2AM20R, the crystal structures demonstrate that this ring assumes the beta-chair conformation in all cases, and the 1alpha-hydroxyl group is equatorial. The peptide folds as a helix and is anchored through hydrogen bonds to a surface groove formed by helices 3, 4, and 12. Electrostatic and hydrophobic interactions between the peptide and the LBD stabilize the active receptor conformation. This stablization appears necessary for crystal growth.

  2. Radiolabeled antibodies for therapy of infectious diseases

    PubMed Central

    Dadachova, Ekaterina; Casadevall, Arturo

    2014-01-01

    Novel approaches to treatment of infectious diseases are urgently needed. This need has resulted in renewing the interest in antibodies for therapy of infectious diseases. Radioimmunotherapy (RIT) is a cancer treatment modality, which utilizes radiolabeled monoclonal antibodies (mAbs). During the last decade we have translated RIT into the field of experimental fungal, bacterial and HIV infections. In addition, successful proof of principle experiments with radiolabeled pan-antibodies that bind to antigens shared by major pathogenic fungi were performed in vitro. The armamentarium of pan-antibodies would result in reducing the dependence on microorganism-specific antibodies and thus would speed up the development of RIT of infections. We believe that the time is ripe for deploying RIT into the clinic to combat infectious diseases. PMID:25599011

  3. Further Studies on 2-Arylacetamide Pyridazin-3(2H)-ones: Design, Synthesis and Evaluation of 4,6-Disubstituted Analogues as Formyl Peptide Receptors (FPRs) Agonists

    PubMed Central

    Giovannoni, Maria Paola; Schepetkin, Igor A.; Cilibrizzi, Agostino; Crocetti, Letizia; Khlebnikov, Andrei I.; Dahlgren, Claes; Graziano, Alessia; Piaz, Vittorio Dal; Kirpotina, Liliya N.; Zerbinati, Serena; Vergelli, Claudia; Quinn, Mark T.

    2013-01-01

    Formyl peptide receptors (FPRs) play an essential role in the regulation of endogenous inflammation and immunity. In the present studies, a large series of pyridazin-3(2H)-one derivatives bearing an arylacetamide chain at position 2 was synthesized and tested for FPR agonist activity. The pyridazin-3(2H)-one ring was confirmed to be an appropriate scaffold to support FPR agonist activity, and its modification at the 4 and 6 positions led to the identification of additional active agonists, which induced intracellular Ca2+ flux in HL-60 cells transfected with either FPR1, FPR2, or FPR3. Seven formyl peptide receptor 1 (FPR1)-specific and several mixed FPR1/FPR2 dual agonists were identified with low micromolar EC50 values. Furthermore, these agonists also activated human neutrophils, inducing intracellular Ca2+ flux and chemotaxis. Finally, molecular docking studies indicated that the most potent pyridazin-3(2H)-ones overlapped in their best docking poses with fMLF and WKYMVM peptides in the FPR1 and FPR2 ligand binding sites, respectively. Thus, pyridazinone-based compounds represent potential lead compounds for further development of selective and/or potent FPR agonists. PMID:23685570

  4. Radiolabeled Metaiodobenzylguanidine for the Treatment of Neuroblastoma

    PubMed Central

    DuBois, Steven G.; Matthay, Katherine K.

    2008-01-01

    Introduction Neuroblastoma is the most common pediatric extracranial solid cancer. This tumor is characterized by metaiodobenzylguanidine (MIBG) avidity in 90% of cases, prompting the use of radiolabeled MIBG for targeted radiotherapy in these tumors. Methods The available English language literature was reviewed for original research investigating in vitro, in vivo, and clinical applications of radiolabeled MIBG for neuroblastoma. Results MIBG is actively transported into neuroblastoma cells by the norepinephrine transporter. Preclinical studies demonstrate substantial activity of radiolabeled MIBG in neuroblastoma models, with 131I-MIBG showing enhanced activity in larger tumors compared to 125I-MIBG. Clinical studies of 131I-MIBG in patients with relapsed or refractory neuroblastoma have identified myelosuppression as the main dose-limiting toxicity, necessitating stem cell reinfusion at higher doses. Most studies report a response rate of 30–40% with 131I-MIBG in this population. More recent studies have focused on the use of 131I-MIBG in combination with chemotherapy or myeloablative regimens. Conclusions 131I-MIBG is an active agent for the treatment of patients with neuroblastoma. Future studies will need to define the optimal role of this targeted radiopharmaceutical in the therapy of this disease. PMID:18707633

  5. Synthesis of fluorine-18 radio-labeled serum albumins for PET blood pool imaging.

    PubMed

    Basuli, Falguni; Li, Changhui; Xu, Biying; Williams, Mark; Wong, Karen; Coble, Vincent L; Vasalatiy, Olga; Seidel, Jurgen; Green, Michael V; Griffiths, Gary L; Choyke, Peter L; Jagoda, Elaine M

    2015-03-01

    We sought to develop a practical, reproducible and clinically translatable method of radiolabeling serum albumins with fluorine-18 for use as a PET blood pool imaging agent in animals and man. Fluorine-18 radiolabeled fluoronicotinic acid-2,3,5,6-tetrafluorophenyl ester, [(18)F]F-Py-TFP was prepared first by the reaction of its quaternary ammonium triflate precursor with [(18)F]tetrabutylammonium fluoride ([(18)F]TBAF) according to a previously published method for peptides, with minor modifications. The incubation of [(18)F]F-Py-TFP with rat serum albumin (RSA) in phosphate buffer (pH9) for 15 min at 37-40 °C produced fluorine-18-radiolabeled RSA and the product was purified using a mini-PD MiniTrap G-25 column. The overall radiochemical yield of the reaction was 18-35% (n=30, uncorrected) in a 90-min synthesis. This procedure, repeated with human serum albumin (HSA), yielded similar results. Fluorine-18-radiolabeled RSA demonstrated prolonged blood retention (biological half-life of 4.8 hours) in healthy awake rats. The distribution of major organ radioactivity remained relatively unchanged during the 4 hour observation periods either by direct tissue counting or by dynamic PET whole-body imaging except for a gradual accumulation of labeled metabolic products in the bladder. This manual method for synthesizing radiolabeled serum albumins uses fluorine-18, a widely available PET radionuclide, and natural protein available in both pure and recombinant forms which could be scaled up for widespread clinical applications. These preclinical biodistribution and PET imaging results indicate that [(18)F]RSA is an effective blood pool imaging agent in rats and might, as [(18)F]HSA, prove similarly useful as a clinical imaging agent.

  6. AaeAP1 and AaeAP2: novel antimicrobial peptides from the venom of the scorpion, Androctonus aeneas: structural characterisation, molecular cloning of biosynthetic precursor-encoding cDNAs and engineering of analogues with enhanced antimicrobial and anticancer activities.

    PubMed

    Du, Qiang; Hou, Xiaojuan; Wang, Lei; Zhang, Yingqi; Xi, Xinping; Wang, Hui; Zhou, Mei; Duan, Jinao; Wei, Minjie; Chen, Tianbao; Shaw, Chris

    2015-01-23

    The main functions of the abundant polypeptide toxins present in scorpion venoms are the debilitation of arthropod prey or defence against predators. These effects are achieved mainly through the blocking of an array of ion channel types within the membranes of excitable cells. However, while these ion channel-blocking toxins are tightly-folded by multiple disulphide bridges between cysteine residues, there are additional groups of peptides in the venoms that are devoid of cysteine residues. These non-disulphide bridged peptides are the subject of much research interest, and among these are peptides that exhibit antimicrobial activity. Here, we describe two novel non-disulphide-bridged antimicrobial peptides that are present in the venom of the North African scorpion, Androctonus aeneas. The cDNAs encoding the biosynthetic precursors of both peptides were cloned from a venom-derived cDNA library using 3'- and 5'-RACE strategies. Both translated precursors contained open-reading frames of 74 amino acid residues, each encoding one copy of a putative novel nonadecapeptide, whose primary structures were FLFSLIPSVIAGLVSAIRN and FLFSLIPSAIAGLVSAIRN, respectively. Both peptides were C-terminally amidated. Synthetic versions of each natural peptide displayed broad-spectrum antimicrobial activities, but were devoid of antiproliferative activity against human cancer cell lines. However, synthetic analogues of each peptide, engineered for enhanced cationicity and amphipathicity, exhibited increases in antimicrobial potency and acquired antiproliferative activity against a range of human cancer cell lines. These data clearly illustrate the potential that natural peptide templates provide towards the design of synthetic analogues for therapeutic exploitation.

  7. Discovery of novel selective hypotensive vasopressin peptides that exhibit little or no functional interactions with known oxytocin/vasopressin receptors

    PubMed Central

    Chan, W Y; Wo, N C; Stoev, S; Cheng, L L; Manning, M

    1998-01-01

    Arginine-vasopressin (VP) has both vasoconstricting and vasodilating action. We report here the discovery of four novel selective hypotensive VP analogues: d(CH2)5[D-Tyr(Et)2,Arg3,Val4]AVP; d(CH2)5[D-Tyr(Et)2,Lys3,Val4]AVP and their iodinatable Tyr-NH29 analogues.Bioassays in rats for activities characteristic of neurohypophysial peptides showed that the four VP peptides possessed little or no V1a, V2 or oxytocin (OT) receptor agonistic or antagonistic activities.In anaesthetized rats, these peptides (0.05–0.10 mg kg−1 i.v.) elicited a marked fall in arterial blood pressure.Blockade of cholinoceptors, adrenoceptors and bradykinin B2 receptors, and inhibition of prostaglandin synthesis had little effect on their vasodepressor action.Classical V1a, V2 and OT receptor antagonists did not block the vasodepressor response.L-NAME, 0.2 mg kg−1 min−1, markedly suppressed the hypotensive response to ACh but not the vasodepressor response to the hypotensive VP peptides. However, the duration of the vasodepressor response was shortened. Very high doses of L-NAME attenuated both the vasodepressor response and the duration of action.These findings indicate that the vasodepressor action of these VP peptides is independent of the peripheral autonomic, bradykinin and PG systems and is not mediated by the known classical OT/VP receptors. NO does not appear to have an important role in their vasodepressor action.The discovery of these novel VP peptides could lead to the development of new tools for the investigation of the complex cardiovascular actions of VP and the introduction of a new class of hypotensive agents. The two iodinatable hypotensive VP peptides could be radiolabelled as potential markers for the localization of the receptor system involved. PMID:9831918

  8. Cell Permeant Peptide Analogues of the Small Heat Shock Protein, HSP20, Reduce TGF-β1-Induced CTGF Expression in Keloid Fibroblasts

    PubMed Central

    Lopes, Luciana B.; Furnish, Elizabeth J.; Komalavilas, Padmini; Flynn, Charles R.; Ashby, Patricia; Hansen, Adam; Ly, Daphne P.; Yang, George P.; Longaker, Michael T.; Panitch, Alyssa; Brophy, Colleen M.

    2009-01-01

    A growing body of evidence suggests the involvement of connective tissue growth factor (CTGF) in the development and maintenance of fibrosis and excessive scarring. As the expression of this protein requires an intact actin cytoskeleton, disruption of the cytoskeleton represents an attractive strategy to decrease CTGF expression and, consequently, excessive scarring. The small heat-shock-related protein (HSP20), when phosphorylated by cyclic nucleotide signaling cascades, displaces phospho-cofilin from the 14-3-3 scaffolding protein leading to activation of cofilin as an actin-depolymerizing protein. In the present study, we evaluated the effect of AZX100, a phosphopeptide analogue of HSP20, on transforming growth factor-β-1 (TGF-β1)-induced CTGF and collagen expression in human keloid fibroblasts. We also examined the effect of AZX100 on scar formation in vivo in dermal wounds in a Siberian hamster model. AZX100 decreased the expression of CTGF and type I collagen induced by TGF-β1, endothelin, and lysophosphatidic acid. Treatment with AZX100 decreased stress fiber formation and altered the morphology of human dermal keloid fibroblasts. In vivo, AZX100 significantly improved collagen organization in a Siberian hamster scarring model. Taken together, these results suggest the potential use of AZX100 as a strategy to prevent excessive scarring and fibrotic disorders. PMID:18787533

  9. A 99mTc-tricine-HYNIC-labeled Peptide Targeting the Melanocortin-1 Receptor for Melanoma Imaging

    PubMed Central

    Shamshirian, Danial; Erfani, Mostafa; Beiki, Davood; Hajiramazanali, Maliheh; Fallahi, Babak

    2016-01-01

    Melanocortin-1 (MC1) receptor is an attractive melanoma-specific target for the development of α-MSH peptide based imaging and therapeutic agents. In this work a new lactam bridge α-MSH analogue was synthesized and radiolabeled with 99mTc via HYNIC chelator and tricine as co-ligand. Also, stability in human serum, receptor bound internalization and tissue biodistribution in tumor bearing nude mice were thoroughly investigated. Radiolabeling with 99mTc was performed at high specific activities (163MBq/nmol) with an acceptable labeling yield (>98%). The radioligand showed specific internalization into B16/F10 cells (13.35 ± 0.9% at 4 h). In biodistribution studies, a receptor-specific uptake was observed in MC1 receptor positive organ so that after 4 h the tumor uptake was 4.51 ± 0.11 % ID/g. Predominant renal excretion pathway with a highest accumulation of activity in tumor was observed for this radiopeptide. Obtained results show that the new designed labeled peptide conjugate can be a suitable candidate for diagnosis of metastatic melanomas. PMID:27980570

  10. Lutetium-labelled peptides for therapy of neuroendocrine tumours.

    PubMed

    Kam, B L R; Teunissen, J J M; Krenning, E P; de Herder, W W; Khan, S; van Vliet, E I; Kwekkeboom, D J

    2012-02-01

    Treatment with radiolabelled somatostatin analogues is a promising new tool in the management of patients with inoperable or metastasized neuroendocrine tumours. Symptomatic improvement may occur with (177)Lu-labelled somatostatin analogues that have been used for peptide receptor radionuclide therapy (PRRT). The results obtained with (177)Lu-[DOTA(0),Tyr(3)]octreotate (DOTATATE) are very encouraging in terms of tumour regression. Dosimetry studies with (177)Lu-DOTATATE as well as the limited side effects with additional cycles of (177)Lu-DOTATATE suggest that more cycles of (177)Lu-DOTATATE can be safely given. Also, if kidney-protective agents are used, the side effects of this therapy are few and mild and less than those from the use of (90)Y-[DOTA(0),Tyr(3)]octreotide (DOTATOC). Besides objective tumour responses, the median progression-free survival is more than 40 months. The patients' self-assessed quality of life increases significantly after treatment with (177)Lu-DOTATATE. Lastly, compared to historical controls, there is a benefit in overall survival of several years from the time of diagnosis in patients treated with (177)Lu-DOTATATE. These findings compare favourably with the limited number of alternative therapeutic approaches. If more widespread use of PRRT can be guaranteed, such therapy may well become the therapy of first choice in patients with metastasized or inoperable neuroendocrine tumours.

  11. 99mTc Labeled Glucagon-Like Peptide-1-Analogue (99mTc-GLP1) Scintigraphy in the Management of Patients with Occult Insulinoma

    PubMed Central

    Sowa-Staszczak, Anna; Trofimiuk-Müldner, Małgorzata; Stefańska, Agnieszka; Tomaszuk, Monika; Buziak-Bereza, Monika; Gilis-Januszewska, Aleksandra; Jabrocka-Hybel, Agata; Głowa, Bogusław; Małecki, Maciej; Bednarczuk, Tomasz; Kamiński, Grzegorz; Kowalska, Aldona; Mikołajczak, Renata; Janota, Barbara; Hubalewska-Dydejczyk, Alicja

    2016-01-01

    Introduction The aim of this study was to assess the utility of [Lys40(Ahx-HYNIC-99mTc/EDDA)NH2]-exendin-4 scintigraphy in the management of patients with hypoglycemia, particularly in the detection of occult insulinoma. Materials and Methods Forty patients with hypoglycemia and increased/confusing results of serum insulin and C-peptide concentration and negative/inconclusive results of other imaging examinations were enrolled in the study. In all patients GLP-1 receptor imaging was performed to localise potential pancreatic lesions. Results Positive results of GLP-1 scintigraphy were observed in 28 patients. In 18 patients postsurgical histopathological examination confirmed diagnosis of insulinoma. Two patients had contraindications to the surgery, one patient did not want to be operated. One patient, who presented with postprandial hypoglycemia, with positive result of GLP-1 imaging was not qualified for surgery and is in the observational group. Eight patients were lost for follow up, among them 6 patients with positive GLP-1 scintigraphy result. One patient with negative scintigraphy was diagnosed with malignant insulinoma. In two patients with negative scintigraphy Munchausen syndrome was diagnosed (patients were taking insulin). Other seven patients with negative results of 99mTcGLP-1 scintigraphy and postprandial hypoglycemia with C-peptide and insulin levels within the limits of normal ranges are in the observational group. We would like to mention that 99mTc-GLP1-SPECT/CT was also performed in 3 pts with nesidioblastosis (revealing diffuse tracer uptake in two and a focal lesion in one case) and in two patients with malignant insulinoma (with the a focal uptake in the localization of a removed pancreatic headin one case and negative GLP-1 1 scintigraphy in the other patient). Conclusions 99mTc-GLP1-SPECT/CT could be helpful examination in the management of patients with hypoglycemia enabling proper localization of the pancreatic lesion and effective

  12. Patient-specific dosimetry in peptide receptor radionuclide therapy: a clinical review.

    PubMed

    Chalkia, M T; Stefanoyiannis, A P; Chatziioannou, S N; Round, W H; Efstathopoulos, E P; Nikiforidis, G C

    2015-03-01

    Neuroendocrine tumours (NETs) belong to a relatively rare class of neoplasms. Nonetheless, their prevalence has increased significantly during the last decades. Peptide receptor radionuclide therapy (PRRT) is a relatively new treatment approach for inoperable or metastasised NETs. The therapeutic effect is based on the binding of radiolabelled somatostatin analogue peptides with NETs' somatostatin receptors, resulting in internal irradiation of tumours. Pre-therapeutic patient-specific dosimetry is essential to ensure that a treatment course has high levels of safety and efficacy. This paper reviews the methods applied for PRRT dosimetry, as well as the dosimetric results presented in the literature. Focus is given on data concerning the therapeutic somatostatin analogue radiopeptides (111)In-[DTPA(0),D-Phe(1)]-octreotide ((111)In-DTPA-octreotide), (90)Y-[DOTA(0),Tyr(3)]-octreotide ((90)Y-DOTATOC) and (177)Lu-[DOTA(0),Tyr(3),Thr(8)]-octreotide ((177)Lu-DOTATATE). Following the Medical Internal Radiation Dose (MIRD) Committee formalism, dosimetric analysis demonstrates large interpatient variability in tumour and organ uptake, with kidneys and bone marrow being the critical organs. The results are dependent on the image acquisition and processing protocol, as well as the dosimetric imaging radiopharmaceutical.

  13. The glucagon-like peptide 1 (GLP-1) analogue, exendin-4, decreases the rewarding value of food: a new role for mesolimbic GLP-1 receptors.

    PubMed

    Dickson, Suzanne L; Shirazi, Rozita H; Hansson, Caroline; Bergquist, Filip; Nissbrandt, Hans; Skibicka, Karolina P

    2012-04-04

    The glucagon-like peptide 1 (GLP-1) system is a recently established target for type 2 diabetes treatment. In addition to regulating glucose homeostasis, GLP-1 also reduces food intake. Previous studies demonstrate that the anorexigenic effects of GLP-1 can be mediated through hypothalamic and brainstem circuits which regulate homeostatic feeding. Here, we demonstrate an entirely novel neurobiological mechanism for GLP-1-induced anorexia in rats, involving direct effects of a GLP-1 agonist, Exendin-4 (EX4) on food reward that are exerted at the level of the mesolimbic reward system. We assessed the impact of peripheral, central, and intramesolimbic EX4 on two models of food reward: conditioned place preference (CPP) and progressive ratio operant-conditioning. Food-reward behavior was reduced in the CPP test by EX4, as rats no longer preferred an environment previously paired to chocolate pellets. EX4 also decreased motivated behavior for sucrose in a progressive ratio operant-conditioning paradigm when administered peripherally. We show that this effect is mediated centrally, via GLP-1 receptors (GLP-1Rs). GLP-1Rs are expressed in several key nodes of the mesolimbic reward system; however, their function remains unexplored. Thus we sought to determine the neurobiological substrates underlying the food-reward effect. We found that the EX4-mediated inhibition of food reward could be driven from two key mesolimbic structures-ventral tegmental area and nucleus accumbens-without inducing concurrent malaise or locomotor impairment. The current findings, that activation of central GLP-1Rs strikingly suppresses food reward/motivation by interacting with the mesolimbic system, indicate an entirely novel mechanism by which the GLP-1R stimulation affects feeding-oriented behavior.

  14. Radiolabeled dimethyl branched long chain fatty acid for heart imaging

    DOEpatents

    Knapp, Jr., Furn F.; Goodman, Mark M.; Kirsch, Gilbert

    1988-08-16

    A radiolabeled long chain fatty acid for heart imaging that has dimethyl branching at one of the carbons of the chain which inhibits the extent to which oxidation can occur. The closer to the carboxyl the branching is positioned, the more limited the oxidation, thereby resulting in prolonged retention of the radiolabeled compound in the heart.

  15. Radiolabeled theranostics: magnetic and gold nanoparticles

    PubMed Central

    Same, Saeideh; Aghanejad, Ayuob; Akbari Nakhjavani, Sattar; Barar, Jaleh; Omidi, Yadollah

    2016-01-01

    Introduction: Growing advances in nanotechnology have facilitated the applications of newly emerged nanomaterials in the field of biomedical/pharmaceutical sciences. Following this trend, the multifunctional nanoparticles (NPs) play a significant role in development of advanced drug delivery systems (DDSs) such as diapeutics/theranostics used for simultaneous diagnosis and therapy. Multifunctional radiolabeled NPs with capability of detecting, visualizing and destroying diseased cells with least side effects have been considered as an emerging filed in presentation of the best choice in solving the therapeutic problems. Functionalized magnetic and gold NPs (MNPs and GNPs, respectively) have produced the potential of nanoparticles as sensitive multifunctional probes for molecular imaging, photothermal therapy and drug delivery and targeting. Methods: In this study, we review the most recent works on the improvement of various techniques for development of radiolabeled magnetic and gold nanoprobes, and discuss the methods for targeted imaging and therapies. Results: The receptor-specific radiopharmaceuticals have been developed to localized radiotherapy in disease sites. Application of advanced multimodal imaging methods and related modality imaging agents labeled with various radioisotopes (e.g., 125I, 111In, 64Cu, 68Ga, 99mTc) and MNPs/GNPs have significant effects on treatment and prognosis of cancer therapy. In addition, the surface modification with biocompatible polymer such as polyethylene glycol (PEG) have resulted in development of stealth NPs that can evade the opsonization and immune clearance. These long-circulating agents can be decorated with homing agents as well as radioisotopes for targeted imaging and therapy purposes. Conclusion: The modified MNPs or GNPs have wide applications in concurrent diagnosis and therapy of various malignancies. Once armed with radioisotopes, these nanosystems (NSs) can be exploited for combined multimodality imaging with

  16. [Dmt(1)]DALDA analogues modified with tyrosine analogues at position 1.

    PubMed

    Cai, Yunxin; Lu, Dandan; Chen, Zhen; Ding, Yi; Chung, Nga N; Li, Tingyou; Schiller, Peter W

    2016-08-01

    Analogues of [Dmt(1)]DALDA (H-Dmt-d-Arg-Phe-Lys-NH2; Dmt=2',6'-dimethyltyrosine), a potent μ opioid agonist peptide with mitochondria-targeted antioxidant activity were prepared by replacing Dmt with various 2',6'-dialkylated Tyr analogues, including 2',4',6'-trimethyltyrosine (Tmt), 2'-ethyl-6'-methyltyrosine (Emt), 2'-isopropyl-6'-methyltyrosine (Imt) and 2',6'-diethyltyrosine (Det). All compounds were selective μ opioid agonists and the Tmt(1)-, Emt(1) and Det(1)-analogues showed subnanomolar μ opioid receptor binding affinities. The Tmt(1)- and Emt(1)-analogues showed improved antioxidant activity compared to the Dmt(1)-parent peptide in the DPPH radical-scavenging capacity assay, and thus are of interest as drug candidates for neuropathic pain treatment.

  17. Preparation and biodistribution of radiolabeled fullerene C60 nanocrystals

    NASA Astrophysics Data System (ADS)

    Nikolić, Nadežda; Vranješ-Ðurić, Sanja; Janković, Drina; Ðokić, Divna; Mirković, Marija; Bibić, Nataša; Trajković, Vladimir

    2009-09-01

    The present study describes for the first time a procedure for the radiolabeling of fullerene (C60) nanocrystals (nanoC60) with Na 125I, as well as the biodistribution of radiolabeled nanoC60 (125I-nanoC60). The solvent exchange method with tetrahydrofuran was used to make colloidal water suspensions of radiolabeled nanoC60 particles. The radiolabeling procedure with the addition of Na 125I to tetrahydrofuran during dissolution of C60 gave a higher radiochemical yield of radiolabeled nanoC60 particles in comparison to the second option, in which Na 125I was added after C60 was dissolved. Using photon correlation spectroscopy and transmission electron microscopy, 125I-nanoC60 particles were found to have a crystalline structure and a mean diameter of 200-250 nm. The 125I-nanoC60 had a particularly high affinity for human serum albumin, displaying 95% binding efficiency after 1 h. Biodistribution studies of 125I-nanoC60 in rats indicated significant differences in tissue accumulation of 125I-nanoC60 and the radioactive tracer Na 125I. The higher accumulation of radiolabeled nanoC60 was observed in liver and spleen, while accumulation in thyroid, stomach, lungs and intestines was significantly lower in comparison to Na 125I. In addition to being useful for testing the biological distribution of nanoC60, the described radiolabeling procedure might have possible applications in cancer radiotherapy.

  18. Targeting of human glioma xenografts in vivo utilizing radiolabeled antibodies

    SciTech Connect

    Williams, J.A.; Wessels, B.W.; Wharam, M.D.; Order, S.E.; Wanek, P.M.; Poggenburg, J.K.; Klein, J.L. )

    1990-06-01

    Radiolabeled antibodies provide a potential basis for selective radiotherapy of human gliomas. We have measured tumor targeting by radiolabeled monoclonal and polyclonal antibodies directed against neuroectodermal and tumor-associated antigens in nude mice bearing human glioma xenografts. Monoclonal P96.5, a mouse IgG2a immunoglobulin, defines an epitope of a human melanoma cell surface protein, and specifically binds the U-251 human glioma as measured by immunoperoxidase histochemistry. 111In-radiolabeled P96.5 specifically targets the U-251 human glioma xenograft and yields 87.0 microCuries (microCi) of tumor activity per gram per 100 microCi injected activity compared to 4.5 microCi following administration of radiolabeled irrelevant monoclonal antibody. Calculations of targeting ratios demonstrate deposited dose to be 11.6 times greater with radiolabeled P96.5 administration compared to irrelevant monoclonal antibody. The proportion of tumor dose found in normal organs is less than 10%, further supporting specific targeting of the human glioma xenograft by this antibody. Monoclonal antibody ZME018, which defines a second melanoma-associated antigen, and polyclonal rabbit antiferritin, which defines a tumor-associated antigen, demonstrate positive immunoperoxidase staining of the tumor, but comparatively decreased targeting. When compared to the 111In-radiolabeled antibody, 90Y-radiolabeled P96.5 demonstrates comparable tumor targeting and percentages of tumor dose found in normal organs. To test the therapeutic potential of 90Y-radiolabeled P96.5, tumors and normal sites were implanted with miniature thermoluminescent dosimeters (TLD). Seven days following administration of 100 microCi 90Y-radiolabeled P96.5, average absorbed doses of 3770, 980, 353, and 274 cGy were observed in tumor, liver, contralateral control site, and total body, respectively.

  19. Conformational analysis of the ΜΒΡ83-99 (Phe91) and ΜΒΡ83-99 (Tyr91) peptide analogues and study of their interactions with the HLA-DR2 and human TCR receptors by using Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Potamitis, C.; Matsoukas, M.-T.; Tselios, T.; Mavromoustakos, T.; Golič Grdadolnik, S.

    2011-09-01

    The two new synthetic analogues of the MBP83-99 epitope substituted at Lys91 (primary TCR contact) with Phe [MBP83-99 (Phe91)] or Tyr [MBP83-99 (Tyr91)], have been structurally elucidated using 1D and 2D high resolution NMR studies. The conformational analysis of the two altered peptide ligands (APLs) has been performed and showed that they adopt a linear and extended conformation which is in agreement with the structural requirements of the peptides that interact with the HLA-DR2 and TCR receptors. In addition, Molecular Dynamics (MD) simulations of the two analogues in complex with HLA-DR2 (DRA, DRB1*1501) and TCR were performed. Similarities and differences of the binding motif of the two analogues were observed which provide a possible explanation of their biological activity. Their differences in the binding mode in comparison with the MBP83-99 epitope may also explain their antagonistic versus agonistic activity. The obtained results clearly indicate that substitutions in crucial amino acids (TCR contacts) in combination with the specific conformational characteristics of the MBP83-99 immunodominant epitope lead to an alteration of their biological activity. These results make the rational drug design intriguing since the biological activity is very sensitive to the substitution and conformation of the mutated MBP epitopes.

  20. Molecular imaging and therapy of cancer with radiolabeled nanoparticles

    PubMed Central

    Hong, Hao; Zhang, Yin; Sun, Jiangtao; Cai, Weibo

    2009-01-01

    Summary This review summarizes the current state-of-the-art of radiolabeled nanoparticles for molecular imaging and internal radiotherapy applications targeting cancer. With the capacity to provide enormous flexibility, radiolabeled nanoparticles have the potential to profoundly impact disease diagnosis and patient management in the near future. Currently, the major challenges facing the research on radiolabeled nanoparticles are desirable (tumor) targeting efficacy, robust chemistry for both radionuclide encapsulation/incorporation and targeting ligand conjugation, favorable safety profile, as well as certain commercial and regulatory hurdles. PMID:20161038

  1. Biological evaluation of (177)Lu-labeled DOTA-Ala(SO3H)-Aminooctanoyl-Gln-Trp-Ala-Val-N methyl Gly-His-Statine-Leu-NH2 for gastrin-releasing peptide receptor-positive prostate tumor targeting.

    PubMed

    Lim, Jae Cheong; Cho, Eun Ha; Kim, Jin Joo; Choi, Sang Mu; Lee, So young; Nam, Sung Soo; Park, Ul Jae; Park, Soo Hyun

    2015-02-01

    Bombesin binds with selectivity and high affinity to a Gastrin-releasing peptide receptor (GRPR), which is highly overexpressed in prostate cancer cells. The present study describes the in vitro and in vivo biological characteristics of DOTA-Ala(SO3H)-Aminooctanoyl-Gln-Trp-Ala-Val-N methyl Gly-His-Statine-Leu-NH2 (DOTA-sBBNA), an antagonist analogue of bombesin peptide for the targeting of GRPR. DOTA-sBBNA was synthesized and labeled with (177)Lu as previously published. A saturation assay on PC-3 human prostate cancer cells revealed that the Kd value of the radiolabeled peptide was 1.88 nM with a maximum binding capacity (Bmax) of 289.3 fmol/10(6) cells. The radio-peptide slowly internalized, and 24.4±0.5% of the total binding was internalized in 4hr. Biodistribution studies were conducted in healthy and PC-3 xenografted balb/c mice, which showed high uptake and retention of tumor-associated radioactivity in PC-3 xenografted mice. The tumor-to-blood ratio was 126.02±9.36 at 1.5hr p.i., and was increased to 216.33±61.58 at 24hr p.i., which means that the radiolabeled peptide was highly accumulated in a tumor and rapidly cleared from the blood pool. The GRPR is also over-expressed in Korean prostate cancer patients. These results suggest that this (177)Lu-labeled peptide has promising characteristics for application in nuclear medicine, namely for the diagnosis and treatment of GRPR over-expressing prostate tumors.

  2. Template polymerization of nucleotide analogues

    NASA Technical Reports Server (NTRS)

    Orgel, L. E.

    1991-01-01

    Recent work on the template-directed reactions of the natural D-nucleotides has made it clear that l-nucleotides and nucleotide-like derivatives of other sugars would strongly inhibit the formation of long oligonucleotides. Consequently, attention is focusing on molecules simpler than nucleotides that might have acted as monomers of an information transfer system. We have begun a general exploration of the template directed reactions of diverse peptide analogues. I will present work by Dr. Taifeng Wu on oxidative oligomerization of phosphorothioates and of Dr. Mary Tohidi on the cyclic polymerization of nucleoside and related cyclic pyrophosphates.

  3. Radiolabeled D-Penicillamine Magnetic Nanocarriers for Targeted Purposes.

    PubMed

    Özyüncü, Seniha Yolcular; Teksöz, Serap; Içhedef, Çiğdem; Medinel, E Ilker; Avci, Çiğir Biray; Gündüz, Cumhur; Ünak, Perihan

    2016-04-01

    The aim of this study is to synthesize D-Penicillamine (D-PA) conjugated magnetic nanocarriers for targeted purposes. Magnetic nanoparticles were prepared by partial reduction method and surface modification was done with an amino silane coupling agent's (structural properties), AEAPS, the particles were characterized by Scanning Electron Microscope (SEM), X-ray Diffraction (XRD). After that D-PA was linked with the magnetic nanoparticles (MNPs) and has been radiolabeled with [99mTc(CO)3]+ core. Quality controls of [99mTc(CO)3-MNP-D-PA] were established by Cd(Te) detector. The radiolabeling efficiency of magnetic nanoparticles ([99mTc(CO)3-MNP-D-PA]) was about 97.05% with good in vitro stability during the 24 hour period. As a parallel study, radiolabeled D-PA complex ([99mTc(CO)3-D-PA]) was prepared with a radiolabeling yield of 97.93%. At the end, biologic activities of binding complexes were investigated on MCF7 human breast cancer cells. Our results show that, radiolabeled magnetic nanoparticles with core [99mTc(CO)3]+ ([99mTc(CO)3-MNP-D-PA]) showed the highest uptake on MCF7 cells which were applied magnetic field in the wells. In that case, result of this study emphasizes that radiolabeled magnetic nanoparticles with core [99mTc(CO)3]+ would support new occurrences of new agents.

  4. Analogue of Melanotan II (MTII): A Novel Melanotropin with Superpotent Action on Frog Skin.

    PubMed

    Gao, Liqian; Yu, Zhiqiang; Meng, Dan; Zheng, Fang; Ong, Yong S; Miao, Peng; Lee, Su S; Wen, Longping

    2015-01-01

    An α-MSH peptide analogue, named MTII (Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]- NH2), is one of the most important ligands of melanotropic receptors but are relatively nonselective. In order to improve the melanotropic activities of the well-characterized MTII analogues, we report here a new analogue by modifying the core structure as well as the size of the cyclic region of MTII peptide. The analogue peptide, Ac-Nle-c[Asp-His-D-Phe-Lys-Trp-Gly-Lys]-OH (F Peptide), in which we replaced Arg at position 8 with Lys and added a Gly to position 10 of the MTII peptide sequence, was synthesized and used as a new melanotropic hormone in controlling rapid color changes in frogs by its actions on mobilizing pigment granule movements within chromatophores. The in vivo responses of chromatophores to MTII and the related analogue F Peptide were studied in frogs. The results show that the F Peptide was a superpotent agonist with similar melanotropic activity to the MTII peptide according to MTII peptide by in vivo studies. The analogue also exhibited ultraprolonged melanotropic activity. The F peptide can be useful in the study of numerous physiological processes, particularly when superpotent and prolonged melanotropic activity is desired.

  5. Radiolabeled Somatostatin Analogues Therapy in Advanced Neuroendocrine Tumors: A Single Centre Experience

    PubMed Central

    Filice, A.; Fraternali, A.; Frasoldati, A.; Asti, M.; Grassi, E.; Massi, L.; Sollini, M.; Froio, A.; Erba, P. A.; Versari, A.

    2012-01-01

    The aim of this study was to assess the efficacy of PRRT in patients with advanced neuroendocrine tumors (NETs). Patients and Methods. From January 2007 to August 2011, we enrolled 65 patients (m/f 38/27; mean age 65 years, range 33–83) with advanced NETs having enhanced SSTR expression, treated with PRRT. The enhanced expression of SSTR was assessed using 68Ga-DOTATOC/DOTATATE PET/CT. Among all the enrolled patients, 6 of them were excluded from the present analysis since they voluntarily interrupted treatment. Mean activity/cycle of 2.6 GBq (90Y-DOTATOC/DOTATATE) or 6.0 GBq (177Lu-DOTATOC/DOTATATE) was administrated intravenously (max 9 cycles). Results. Complete response (CR) was found in 1/59 (2%) patients, partial remission (PR) in 24/59 (40.5%) patients, stable disease (SD) in 24/59 (40.5%), and progression (PD) in 10/59 (17%) patients. The overall tumor response rate (CR + PR) was 42.5%. In 40.5% of patients, the disease could be stabilized. Overall, 49 out of 59 patients had no tumor progression (83%). Twelve patients out of 59 (20%) had grade 2-3 hematological side effects including anemia, thrombocytopenia, and leukopenia. Long-term nephrotoxicity was observed in 3 patients (2 moderate, 1 severe). Conclusions. PRRT is a promising perspective for patients with advanced NETs. PMID:22934111

  6. Macrocyclization of Unprotected Peptide Isocyanates.

    PubMed

    Vinogradov, Alexander A; Choo, Zi-Ning; Totaro, Kyle A; Pentelute, Bradley L

    2016-03-18

    A chemistry for the facile two-component macrocyclization of unprotected peptide isocyanates is described. Starting from peptides containing two glutamic acid γ-hydrazide residues, isocyanates can be readily accessed and cyclized with hydrazides of dicarboxylic acids. The choice of a nucleophilic linker allows for the facile modulation of biochemical properties of a macrocyclic peptide. Four cyclic NYAD-1 analogues were synthesized using the described method and displayed a range of biological activities.

  7. Potentiation of Peptide Receptor Radionuclide Therapy by the PARP Inhibitor Olaparib

    PubMed Central

    Nonnekens, Julie; van Kranenburg, Melissa; Beerens, Cecile E.M.T.; Suker, Mustafa; Doukas, Michael; van Eijck, Casper H.J.; de Jong, Marion; van Gent, Dik C.

    2016-01-01

    Metastases expressing tumor-specific receptors can be targeted and treated by binding of radiolabeled peptides (peptide receptor radionuclide therapy or PRRT). For example, patients with metastasized somatostatin receptor-positive neuroendocrine tumors (NETs) can be treated with radiolabeled somatostatin analogues, resulting in strongly increased progression-free survival and quality of life. There is nevertheless still room for improvement, as very few patients can be cured at this stage of disease. We aimed to specifically sensitize replicating tumor cells without further damage to healthy tissues. Thereto we investigated the DNA damaging effects of PRRT with the purpose to enhance these effects through modulation of the DNA damage response. Although PRRT induces DNA double strand breaks (DSBs), a larger fraction of the induced lesions are single strand breaks (expected to be similar to those induced by external beam radiotherapy) that require poly-[ADP-ribose]-polymerase 1 (PARP-1) activity for repair. If these breaks cannot be repaired, they will cause replication fork arrest and DSB formation during replication. Therefore, we used the PARP-1 inhibitor Olaparib to increase the number of cytotoxic DSBs. Here we show that this new combination strategy synergistically sensitized somatostatin receptor expressing cells to PRRT. We observed increased cell death and reduced cellular proliferation compared to the PRRT alone. The enhanced cell death was caused by increased numbers of DSBs that are repaired with remarkably slow kinetics, leading to genome instability. Furthermore, we validated the increased DSB induction after PARP inhibitor addition in the clinically relevant model of living human NET slices. We expect that this combined regimen can thus augment current PRRT outcomes. PMID:27570553

  8. Microfluidics for synthesis of peptide-based PET tracers.

    PubMed

    Liu, Yang; Tian, Mei; Zhang, Hong

    2013-01-01

    Positron emission tomography (PET) is a powerful noninvasive tool for acquisition of the physiological parameters in human and animals with the help of PET tracers. Among all the PET tracers, radiolabeled peptides have been widely explored for cancer-related receptor imaging due to their high affinity and specificity to receptors. But radiochemistry procedures for production of peptide-based PET tracers are usually complex, which makes large-scale clinical studies relatively challenging. New radiolabeling technologies which could simplify synthesis and purification procedures, are extremely needed. Over the last decade, microfluidics and lab-on-a-chip (LOC) technology have boomed as powerful tools in the field of organic chemistry, which potentially provide significant help to the PET chemistry. In this minireview, microfluidic radiolabeling technology is described and its application for synthesis of peptide-based PET tracers is summarized and discussed.

  9. Radiolabeled nanobodies as theranostic tools in targeted radionuclide therapy of cancer

    PubMed Central

    D’Huyvetter, Matthias; Xavier, Catarina; Caveliers, Vicky; Lahoutte, Tony; Muyldermans, Serge; Devoogdt, Nick

    2014-01-01

    Introduction: The integration of diagnostic testing for the presence of a molecular target is of interest to predict successful targeted radionuclide therapy (TRNT). This so-called ‘theranostic’ approach aims to improve personalized treatment based on the molecular characteristics of cancer cells. Moreover, it offers new insights in predicting adverse effects and provides appropriate tools to monitor therapy responses. Recent findings using nanobodies emphasize their potential as theranostic tools in cancer treatment. Nanobodies are recombinant, small antigen-binding fragments that are derived from camelid heavy-chain-only antibodies. Areas covered: We review the current status of theranostic approaches in TRNT, with a focus on antibodies, peptides, scaffold proteins and emerging nanobodies. In recent years, nanobodies have been evaluated intensively for molecular imaging. In addition, novel data on TRNT using radiolabeled nanobodies for carcinomas and multiple myeloma highlight their promising opportunities in cancer treatment. Expert opinion: We trust that radiolabeled nanobodies will have a future potential as theranostic tools in cancer therapy, both for diagnosis as well as for TRNT. PMID:25035968

  10. Synthesis, biological evaluation, and automated docking of constrained analogues of the opioid peptide H-Dmt-D-Ala-Phe-Gly-NH₂ using the 4- or 5-methyl substituted 4-amino-1,2,4,5-tetrahydro-2-benzazepin-3-one scaffold.

    PubMed

    De Wachter, Rien; de Graaf, Chris; Keresztes, Atilla; Vandormael, Bart; Ballet, Steven; Tóth, Géza; Rognan, Didier; Tourwé, Dirk

    2011-10-13

    The Phe(3) residue of the N-terminal tetrapeptide of dermorphin (H-Dmt-d-Ala-Phe-Gly-NH(2)) was conformationally constrained using 4- or 5-methyl-substituted 4-amino-1,2,4,5-tetrahydro-2-benzazepin-3-one (Aba) stereoisomeric scaffolds. Several of the synthesized peptides were determined to be high affinity agonists for the μ opioid receptor (OPRM) with selectivity over the δ opioid receptor (OPRD). Interesting effects of the Aba configuration on ligand binding affinity were observed. H-Dmt-d-Ala-erythro-(4S,5S)-5-Me-Aba-Gly-NH(2)9 and H-Dmt-threo-(4R,5S)-5-Me-Aba-Gly-NH(2)12 exhibited subnanomolar affinity for OPRM, while they possess an opposite absolute configuration at position 4 of the Aba ring. However, in the 4-methyl substituted analogues, H-Dmt-d-Ala-(4R)-Me-Aba-Gly-NH(2)14 was significantly more potent than the (4S)-derivative 13. These unexpected results were rationalized using the binding poses predicted by molecular docking simulations. Interestingly, H-Dmt-d-Ala-(4R)-Me-Aba-Gly-NH(2)14 is proposed to bind in a different mode compared with the other analogues. Moreover, in contrast to Ac-4-Me-Aba-NH-Me, which adopts a β-turn in solution and in the crystal structure, the binding mode of this analogue suggests an alternative receptor-bound conformation.

  11. Emerging role of radiolabeled nanoparticles as an effective diagnostic technique

    PubMed Central

    2012-01-01

    Nanomedicine is emerging as a promising approach for diagnostic applications. Nanoparticles are structures in the nanometer size range, which can present different shapes, compositions, charges, surface modifications, in vitro and in vivo stabilities, and in vivo performances. Nanoparticles can be made of materials of diverse chemical nature, the most common being metals, metal oxides, silicates, polymers, carbon, lipids, and biomolecules. Nanoparticles exist in various morphologies, such as spheres, cylinders, platelets, and tubes. Radiolabeled nanoparticles represent a new class of agent with great potential for clinical applications. This is partly due to their long blood circulation time and plasma stability. In addition, because of the high sensitivity of imaging with radiolabeled compounds, their use has promise of achieving accurate and early diagnosis. This review article focuses on the application of radiolabeled nanoparticles in detecting diseases such as cancer and cardiovascular diseases and also presents an overview about the formulation, stability, and biological properties of the nanoparticles used for diagnostic purposes. PMID:22809406

  12. Radiolabeled biomolecules for early cancer detection and therapy via angiogenesis targeting

    NASA Astrophysics Data System (ADS)

    Bouziotis, P.; Psimadas, D.; Fani, M.; Gourni, E.; Loudos, G.; Xanthopoulos, S.; Archimandritis, S. C.; Varvarigou, A. D.

    2006-12-01

    Tumors cannot grow or metastasize without the formation of new blood vessels, i.e. without angiogenesis. A variety of anti-angiogenic agents leading to angiogenesis inhibition are in the clinical trial phase, among which are: (i) molecules which inhibit the action of Vascular Endothelial Growth Factors, VEGF and (ii) molecules which obstruct migration, differentiation and proliferation of endothelial cells, via their binding to receptors of the α νβ 3 integrins. Certain derivatives of the abovementioned categories, labeled with radionuclides, which emit γ-radiation or β-particles or positrons, have been proposed and are being evaluated as possible radiopharmaceuticals, for the detection and/or treatment of primary or metastatic cancer at an early stage. For the study of angiogenesis the following have been described: (a) antibodies targeting VEGF, labeled with radionuclides emitting β- and/or γ-radiation, which can be applied for the diagnosis and, possibly, for the treatment of cancer, (b) peptide derivatives which contain the amino-acid sequence RGD (Arg-Gly-Asp) and compete for the α νβ 3 integrins, with the proteins of the stroma. It has been found that these radiolabeled biomolecules localize in tumors and can be used for the visualization and, possibly, for tumor eradication of primary and metastatic cancer. In our laboratory radiolabeling of biomolecules by beta and/or gamma emitters is a principal research goal. In the present work we are presenting our results on the labeling of monoclonal antibodies and peptides with β- and γ-emitting isotopes, as well as on their in vivo evaluation in experimental animal models, by use of specially dedicated imaging devices.

  13. Radiation safety issues related to radiolabeled antibodies. [Contains glossary

    SciTech Connect

    Barber, D.E.; Baum, J.W.; Meinhold, C. B. )

    1991-03-01

    Techniques related to the use of radiolabeled antibodies in humans are reviewed and evaluated in this report. It is intended as an informational resource for the US Nuclear Regulatory Commission (NRC) and NRC licensees. Descriptions of techniques and health and safety issues are provided. Principal methods for labeling antibodies are summarized to help identify related radiation safety problems in the preparation of dosages for administration to patients. The descriptions are derived from an extensive literature review and consultations with experts in the field. A glossary of terms and acronyms is also included. An assessment was made of the extent of the involvement of organizations (other than the NRC) with safety issues related to radiolabeled antibodies, in order to identify regulatory issues which require attention. Federal regulations and guides were also reviewed for their relevance. A few (but significant) differences between the use of common radiopharmaceuticals and radiolabeled antibodies were observed. The clearance rate of whole, radiolabeled immunoglobulin is somewhat slower than common radiopharmaceuticals, and new methods of administration are being used. New nuclides are being used or considered (e.g., Re-186 and At-211) for labeling antibodies. Some of these nuclides present new dosimetry, instrument calibration, and patient management problems. Subjects related to radiation safety that require additional research are identified. 149 refs., 3 figs., 20 tabs.

  14. Synthesis, Radiolabeling, and Bioevaluation of Bis(Trifluoromethanesulfonyl) Imide.

    PubMed

    Ersöz, Onur Alp; Soylu, Hale Melis; Er, Ozge; Ocakoglu, Kasim; Lambrecht, Fatma Yurt; Yilmaz, Osman

    2015-11-01

    Imidazolium salts have antitumor potential and toxicological effects on various microorganisms. The authors' aim is to synthesize a new imidazolium salt and to assess its pharmacokinetic and antitumor potentials by in vitro and in vivo studies. In this study, bis(trifluoromethanesulfonyl) imide (ITFSI) was synthesized and labeled with (131)I using the iodogen method. The efficiency of radiolabeling was determined with high yield (95.5% ± 3.7%). Pharmacokinetic properties of the compound were investigated in albino Wistar rats using radiolabeled compound. The radiolabeled compound ((131)I-ITFSI) has been stable during a period of 3 hours in human serum. The uptake of (131)I-ITFSI reached maximum in the spleen, liver, and blood at 60 minutes, large intestine and heart at 30 minutes, and ovary at 120 minutes. It is observed that intracellular uptake of the radiolabeled compound is higher in the CaCo-2 (colon adenocarcinoma tumor) cell line than HEK-293 (human epithelial kidney) cell line. In further study, antitumor potential of ITFSI on a colon adenocarcinoma tumor-bearing animal model may be investigated.

  15. Radiolabeling of Cramoll 1,4: Evaluation of the Biodistribution

    PubMed Central

    Ferreira de Carvalho Patricio, Beatriz; Lima-Ribeiro, Maria Helena Madruga; dos Santos Correia, Maria Tereza; dos Anjos Carneiro-Leão, Ana Maria; de Souza Albernaz, Marta; Barboza, Thiago; de Souza, Sergio Augusto Lopes; Santos-Oliveira, Ralph

    2011-01-01

    The cramoll 1,4 is a well-studied lectin. However, few studies about its biodistribution have been done before. In this study, we radiolabeled the cramol 1,4 with Tc-99m and analyzed the biodistribution. The results showed that the cramol has an abnormal uptake by the bowel with reflections on its clearance mechanism. PMID:21760823

  16. Peptide YY receptors in the brain

    SciTech Connect

    Inui, A.; Oya, M.; Okita, M.; Inoue, T.; Sakatani, N.; Morioka, H.; Shii, K.; Yokono, K.; Mizuno, N.; Baba, S.

    1988-01-15

    Radiolabelled ligand binding studies demonstrated that specific receptors for peptide YY are present in the porcine as well as the canine brains. Peptide YY was bound to brain tissue membranes via high-affinity (dissociation constant, 1.39 X 10(-10)M) and low-affinity (dissociation constant, 3.72 X 10(-8)M) components. The binding sites showed a high specificity for peptide YY and neuropeptide Y, but not for pancreatic polypeptide or structurally unrelated peptides. The specific activity of peptide YY binding was highest in the hippocampus, followed by the pituitary gland, the hypothalamus, and the amygdala of the porcine brain, this pattern being similarly observed in the canine brain. The results suggest that peptide YY and neuropeptide Y may regulate the function of these regions of the brain through interaction with a common receptor site.

  17. Characterization of 12 GnRH peptide agonists – a kinetic perspective

    PubMed Central

    Nederpelt, Indira; Georgi, Victoria; Schiele, Felix; Nowak‐Reppel, Katrin; Fernández‐Montalván, Amaury E.; IJzerman, Adriaan P.

    2015-01-01

    Background and Purpose Drug‐target residence time is an important, yet often overlooked, parameter in drug discovery. Multiple studies have proposed an increased residence time to be beneficial for improved drug efficacy and/or longer duration of action. Currently, there are many drugs on the market targeting the gonadotropin‐releasing hormone (GnRH) receptor for the treatment of hormone‐dependent diseases. Surprisingly, the kinetic receptor‐binding parameters of these analogues have not yet been reported. Therefore, this project focused on determining the receptor‐binding kinetics of 12 GnRH peptide agonists, including many marketed drugs. Experimental Approach A novel radioligand‐binding competition association assay was developed and optimized for the human GnRH receptor with the use of a radiolabelled peptide agonist, [125I]‐triptorelin. In addition to radioligand‐binding studies, a homogeneous time‐resolved FRET Tag‐lite™ method was developed as an alternative assay for the same purpose. Key Results Two novel competition association assays were successfully developed and applied to determine the kinetic receptor‐binding characteristics of 12 high‐affinity GnRH peptide agonists. Results obtained from both methods were highly correlated. Interestingly, the binding kinetics of the peptide agonists were more divergent than their affinities with residence times ranging from 5.6 min (goserelin) to 125 min (deslorelin). Conclusions and Implications Our research provides new insights by incorporating kinetic, next to equilibrium, binding parameters in current research and development that can potentially improve future drug discovery targeting the GnRH receptor. PMID:26398856

  18. Survey of Analogue Spacetimes

    NASA Astrophysics Data System (ADS)

    Visser, Matt

    Analogue spacetimes (and more boldly, analogue models both of and for gravity), have attracted significant and increasing attention over the last decade and a half. Perhaps the most straightforward physical example, which serves as a template for most of the others, is Bill Unruh's model for a dumb hole,(mute black hole, acoustic black hole), wherein sound is dragged along by a moving fluid—and can even be trapped behind an acoustic horizon. This and related analogue models for curved spacetimes are useful in many ways: analogue spacetimes provide general relativists with extremely concrete physical models to help focus their thinking, and conversely the techniques of curved spacetime can sometimes help improve our understanding of condensed matter and/or optical systems by providing an unexpected and countervailing viewpoint. In this chapter, I shall provide a few simple examples of analogue spacetimes as general background for the rest of the contributions.

  19. Solid-phase peptide head-to-side chain cyclodimerization: discovery of C(2)-symmetric cyclic lactam hybrid α-melanocyte-stimulating hormone (MSH)/agouti-signaling protein (ASIP) analogues with potent activities at the human melanocortin receptors.

    PubMed

    Mayorov, Alexander V; Cai, Minying; Palmer, Erin S; Liu, Zhihua; Cain, James P; Vagner, Josef; Trivedi, Dev; Hruby, Victor J

    2010-10-01

    A novel hybrid melanocortin pharmacophore was designed based on the pharmacophores of the agouti-signaling protein (ASIP), an endogenous melanocortin antagonist, and α-melanocyte-stimulating hormone (α-MSH), an endogenous melanocortin agonist. The designed hybrid ASIP/MSH pharmacophore was explored in monomeric cyclic, and cyclodimeric templates. The monomeric cyclic disulfide series yielded peptides with hMC3R-selective non-competitive binding affinities. The direct on-resin peptide lactam cyclodimerization yielded nanomolar range (25-120 nM) hMC1R-selective full and partial agonists in the cyclodimeric lactam series which demonstrates an improvement over the previous attempts at hybridization of MSH and agouti protein sequences. The secondary structure-oriented pharmacophore hybridization strategy will prove useful in development of unique allosteric and orthosteric melanocortin receptor modulators. This report also illustrates the utility of peptide cyclodimerization for the development of novel GPCR peptide ligands.

  20. Radiolabeling of substance P with lutetium-177 and biodistribution study in rat pancreatic tumor xenografted nude mice.

    PubMed

    De Araújo, E B; Pujatti, P B; Mengatti, J

    2010-05-10

    Pancreatic tumor (PT) is a neuroendocrine neoplasm that usually origin metastases in the respiratory and gastrointestinal tract. The presence of peptide receptors at the cell membrane of PT constitutes the basis of the clinical use of specific radiolabeled ligands for its diagnosis and targeted therapy. Substance P (SP), an 11-amino acid peptide which has an important role in modulating pain transmission trough neurokinin type 1 (NK1r) and 2 receptors (NK2r), may play a role in the pathogenesis of PT, because approximately 10% of these tumors overexpress NK1r. The aim of the present work was to produce a pure and stable SP analog (DOTA-SP) radiolabeled with lutetium-177 ((177)Lu), and to evaluate its in vivo target to AR42J pancreatic tumor cells in Nude mice, in other to verify if SP can be used in this pancreatic tumor detection and treatment. Substance P was successfully labeled with high yield (>99%) at optimized conditions and kept stable for more than 72 hours at 2-8 degrees C and 4 hours in human plasma. Biodistribution studies showed that SP excretion was mainly performed by renal pathway. In addition, (177)Lu-DOTA-SP showed higher uptake by tumor than normal pancreas, indicating the presence of NK receptors in AR42J pancreatic tumor.

  1. Complementary optical and nuclear imaging of caspase-3 activity using combined activatable and radio-labeled multimodality molecular probe

    NASA Astrophysics Data System (ADS)

    Lee, Hyeran; Akers, Walter J.; Cheney, Philip P.; Edwards, W. Barry; Liang, Kexian; Culver, Joseph P.; Achilefu, Samuel

    2009-07-01

    Based on the capability of modulating fluorescence intensity by specific molecular events, we report a new multimodal optical-nuclear molecular probe with complementary reporting strategies. The molecular probe (LS498) consists of tetraazacyclododecanetetraacetic acid (DOTA) for chelating a radionuclide, a near-infrared fluorescent dye, and an efficient quencher dye. The two dyes are separated by a cleavable peptide substrate for caspase-3, a diagnostic enzyme that is upregulated in dying cells. LS498 is radiolabeled with 64Cu, a radionuclide used in positron emission tomography. In the native form, LS498 fluorescence is quenched until caspase-3 cleavage of the peptide substrate. Enzyme kinetics assay shows that LS498 is readily cleaved by caspase-3, with excellent enzyme kinetic parameters kcat and KM of 0.55+/-0.01 s-1 and 1.12+/-0.06 μM, respectively. In mice, the initial fluorescence of LS498 is ten-fold less than control. Using radiolabeled 64Cu-LS498 in a controlled and localized in-vivo model of caspase-3 activation, a time-dependent five-fold NIR fluorescence enhancement is observed, but radioactivity remains identical in caspase-3 positive and negative controls. These results demonstrate the feasibility of using radionuclide imaging for localizing and quantifying the distribution of molecular probes and optical imaging for reporting the functional status of diagnostic enzymes.

  2. Derivatisable Cyanobactin Analogues: A Semisynthetic Approach

    PubMed Central

    Oueis, Emilia; Adamson, Catherine; Mann, Greg; Ludewig, Hannes; Redpath, Philip; Migaud, Marie

    2015-01-01

    Abstract Many natural cyclic peptides have potent and potentially useful biological activities. Their use as therapeutic starting points is often limited by the quantities available, the lack of known biological targets and the practical limits on diversification to fine‐tune their properties. We report the use of enzymes from the cyanobactin family to heterocyclise and macrocyclise chemically synthesised substrates so as to allow larger‐scale syntheses and better control over derivatisation. We have made cyclic peptides containing orthogonal reactive groups, azide or dehydroalanine, that allow chemical diversification, including the use of fluorescent labels that can help in target identification. We show that the enzymes are compatible and efficient with such unnatural substrates. The combination of chemical synthesis and enzymatic transformation could help renew interest in investigating natural cyclic peptides with biological activity, as well as their unnatural analogues, as therapeutics. PMID:26507241

  3. Effectiveness of quenchers to reduce radiolysis of (111)In- or (177)Lu-labelled methionine-containing regulatory peptides. Maintaining radiochemical purity as measured by HPLC.

    PubMed

    de Blois, Erik; Chan, Ho Sze; Konijnenberg, Mark; de Zanger, Rory; Breeman, Wouter A P

    2012-01-01

    An overview how to measure and to quantify radiolysis by the addition of quenchers and to maintain Radio-Chemical Purity (RCP) of vulnerable methionine-containing regulatory peptides is presented. High RCP was only achieved with a combination of quenchers. However, quantification of RCP is not standardized, and therefore comparison of radiolabelling and RCP of regulatory peptides between different HPLC-systems and between laboratories is cumbersome. Therefore we suggest a set of standardized requirements to quantify RCP by HPLC for radiolabelled DTPA- or DOTA-peptides. Moreover, a dosimetry model was developed to calculate the doses in the reaction vials during radiolabelling and storage of the radiopeptides, and to predict RCP in the presence and absence of quenchers. RCP was measured by HPLC, and a relation between radiation dose and radiolysis of RCP was established. The here described quenchers are tested individually as ƒ(concentration) to investigate efficacy to reduce radiolysis of radiolabelled methionine-containing regulatory peptides.

  4. Multistep synthesis of a radiolabeled imaging probe using integrated microfluidics.

    PubMed

    Lee, Chung-Cheng; Sui, Guodong; Elizarov, Arkadij; Shu, Chengyi Jenny; Shin, Young-Shik; Dooley, Alek N; Huang, Jiang; Daridon, Antoine; Wyatt, Paul; Stout, David; Kolb, Hartmuth C; Witte, Owen N; Satyamurthy, Nagichettiar; Heath, James R; Phelps, Michael E; Quake, Stephen R; Tseng, Hsian-Rong

    2005-12-16

    Microreactor technology has shown potential for optimizing synthetic efficiency, particularly in preparing sensitive compounds. We achieved the synthesis of an [(18)F]fluoride-radiolabeled molecular imaging probe, 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG), in an integrated microfluidic device. Five sequential processes-[18F]fluoride concentration, water evaporation, radiofluorination, solvent exchange, and hydrolytic deprotection-proceeded with high radio-chemical yield and purity and with shorter synthesis time relative to conventional automated synthesis. Multiple doses of [18F]FDG for positron emission tomography imaging studies in mice were prepared. These results, which constitute a proof of principle for automated multistep syntheses at the nanogram to microgram scale, could be generalized to a range of radiolabeled substrates.

  5. Dosimetric aspects of radiolabeled antibodies for tumor therapy

    SciTech Connect

    Humm, J.L.

    1986-09-01

    Radioimmunotherapy (RIT) is rapidly attracting interest as a potential new weapon in the arsenal for cancer therapy. This article concentrates on some of the dosimetric aspects affecting the potential success of RIT, and examines factors which influence the choice of a radiolabel for RIT. No radionuclide is likely to give an optimum tumor/nontumor insult for all tumor types; therefore, the concept of matching the source to tumor morphology is introduced. Lists of candidate radionuclides are given, classified according to the type of decay, range, and energy of the emission. The article examines how the choice of radionuclide for radiolabeling the antibody affects the local energy deposition in the tumor. Both the effect of tumor size on the energy absorbed fraction and the problem of antibody binding heterogeneity are discussed. The approach to RIT is to relate the choice of radionuclide to the physical properties of the tumor. 26 references.

  6. Internal radiation dosimetry for clinical testing of radiolabeled monoclonal antibodies

    SciTech Connect

    Fisher, D.R.; Durham, J.S.; Hui, T.E.; Hill, R.L.

    1990-11-01

    In gauging the efficacy of radiolabeled monoclonal antibodies in cancer treatment, it is important to know the amount of radiation energy absorbed by tumors and normal tissue per unit administered activity. This paper describes methods for estimating absorbed doses to human tumors and normal tissues, including intraperitoneal tissue surfaces, red marrow, and the intestinal tract from incorporated radionuclides. These methods use the Medical Internal Radiation Dose (MIRD) scheme; however, they also incorporate enhancements designed to solve specific dosimetry problems encountered during clinical studies, such as patient-specific organ masses obtained from computerized tomography (CT) volumetrics, estimates of the dose to tumor masses within normal organs, and multicellular dosimetry for studying dose inhomogeneities in solid tumors. Realistic estimates of absorbed dose are provided within the short time requirements of physicians so that decisions can be made with regard to patient treatment and procurement of radiolabeled antibodies. Some areas in which further research could improve dose assessment are also discussed. 16 refs., 3 figs.

  7. Method to directly radiolabel antibodies for diagnostic imaging and therapy

    DOEpatents

    Thakur, Mathew L.

    1994-01-01

    The invention is a novel method and kit for directly radiolabeling proteins such as antibodies or antibody fragments for diagnostic and therapeutic purposes. The method comprises incubating a protein-containing solution with a solution of sodium ascorbate; adding a required quantity of reduced radionuclide to the incubated protein. A kit is also provided wherein the protein and/or reducing agents may be in lyophilized form.

  8. Method to directly radiolabel antibodies for diagnostic imaging and therapy

    DOEpatents

    Thakur, Mathew L.

    1991-01-01

    The invention is a novel method and kit for directly radiolabeling proteins such as antibodies or antibody fragments for diagnostic and therapeutic purposes. The method comprises incubating a protein-containing solution with a solution of sodium ascorbate; adding a required quantity of reduced radionuclide to the incubated protein. A kit is also provided wherein the protein and/or reducing agents may be in lyophilized form.

  9. Method to directly radiolabel antibodies for diagnostic imaging and therapy

    SciTech Connect

    Thakur, M.L.

    1994-05-03

    The invention is a novel method and kit for directly radiolabeling proteins such as antibodies or antibody fragments for diagnostic and therapeutic purposes. The method comprises incubating a protein-containing solution with a solution of sodium ascorbate; adding a required quantity of reduced radionuclide to the incubated protein. A kit is also provided wherein the protein and/or reducing agents may be in lyophilized form. No Drawings

  10. Immunolocalization of neuroblastoma using radiolabeled monoclonal antibody UJ13A

    SciTech Connect

    Goldman, A.; Vivian, G.; Gordon, I.; Pritchard, J.; Kemshead, J.

    1984-08-01

    The monoclonal antibody UJ13A, raised after immunization of mice with human fetal brain, recognized an antigen expressed on human neuroblastoma cell lines and fresh tumors. Antibody was purified and radiolabeled with iodine isotopes using chloramine-T. In preclinical studies, 125I-labeled UJ13A was injected intravenously into nude mice bearing xenografts of human neuroblastoma. Radiolabeled UJ13A uptake by the tumors was four to 23 times greater than that by blood. In control animals, injected with a similar quantity of a monoclonal antibody known not to bind to neuroblastoma cells in vitro (FD44), there was no selective tumor uptake. Nine patients with histologically confirmed neuroblastoma each received 100 to 300 micrograms UJ13A radiolabeled with 1 to 2.8 mCi 123I or 131I. Sixteen positive sites were visible on gamma scans 1 to 7 days after injection: 15 were primary or secondary tumor sites, and one was a false positive; there were two false negatives. In two of the 15 positive sites, tumor had not been demonstrated by other imaging techniques; these were later confirmed as areas of malignant infiltration. No toxicity was encountered.

  11. Radiosynthesis and 'click' conjugation of ethynyl-4-[(18)F]fluorobenzene--an improved [(18)F]synthon for indirect radiolabeling.

    PubMed

    Roberts, Maxine P; Pham, Tien Q; Doan, John; Jiang, Cathy D; Hambley, Trevor W; Greguric, Ivan; Fraser, Benjamin H

    2015-01-01

    Reproducible methods for [(18)F]radiolabeling of biological vectors are essential for the development of new [(18)F]radiopharmaceuticals. Molecules such as carbohydrates, peptides and proteins are challenging substrates that often require multi-step indirect radiolabeling methods. With the goal of developing more robust, time saving, and less expensive procedures for indirect [(18)F]radiolabeling of such molecules, our group has synthesized ethynyl-4-[(18)F]fluorobenzene ([(18)F]2, [(18)F]EYFB) in a single step (14 ± 2% non-decay corrected radiochemical yield (ndc RCY)) from a readily synthesized, shelf stable, inexpensive precursor. The alkyne-functionalized synthon [(18)F]2 was then conjugated to two azido-functionalized vector molecules via CuAAC reactions. The first 'proof of principle' conjugation of [(18)F]2 to 1-azido-1-deoxy-β-D-glucopyranoside (3) gave the desired radiolabeled product [(18)F]4 in excellent radiochemical yield (76 ± 4% ndc RCY (11% overall)). As a second example, the conjugation of [(18)F]2 to matrix-metalloproteinase inhibitor (5), which has potential in tumor imaging, gave the radiolabeled product [(18)F]6 in very good radiochemical yield (56 ± 12% ndc RCY (8% overall)). Total preparation time for [(18)F]4 and [(18)F]6 including [(18)F]F(-) drying, two-step reaction (nucleophilic substitution and CuAAC conjugation), two HPLC purifications, and two solid phase extractions did not exceed 70 min. The radiochemical purity of synthon [(18)F]2 and the conjugated products, [(18)F]4 and [(18)F]6, were all greater than 98%. The specific activities of [(18)F]2 and [(18)F]6 were low, 5.97 and 0.17 MBq nmol(-1), respectively.

  12. In vitro and in vivo evaluation of Alexa Fluor 680-bombesin[7-14]NH2 peptide conjugate, a high-affinity fluorescent probe with high selectivity for the gastrin-releasing peptide receptor.

    PubMed

    Ma, Lixin; Yu, Ping; Veerendra, Bhadrasetty; Rold, Tammy L; Retzloff, Lauren; Prasanphanich, Adam; Sieckman, Gary; Hoffman, Timothy J; Volkert, Wynn A; Smith, Charles J

    2007-01-01

    Gastrin-releasing peptide (GRP) receptors are overexpressed on several types of human cancer cells, including breast, prostate, small cell lung, and pancreatic cancers. Bombesin (BBN), a 14-amino acid peptide that is an analogue of human GRP, binds to GRP receptors with very high affinity and specificity. The aim of this study was to develop a new fluorescent probe based on BBN having high tumor uptake and optimal pharmacokinetics for specific targeting and optical imaging of human breast cancer tissue. In this study, solid-phase peptide synthesis was used to produce H(2)N-glycylglycylglycine-BBN[7-14]NH(2) peptide with the following general sequence: H(2)N-G-G-G-Q-W-A-V-G-H-L-M-(NH(2)). This conjugate was purified by reversed-phase high-performance liquid chromatography and characterized by electrospray-ionization mass spectra. The fluorescent probe Alexa Fluor 680-G-G-G-BBN[7-14]NH(2) conjugate was prepared by reaction of Alexa Fluor 680 succinimidyl ester to H(2)N-G-G-G-BBN[7-14]NH(2) in dimethylformamide (DMF). In vitro competitive binding assays, using (125)I-Tyr(4)-BBN as the radiolabeling gold standard, demonstrated an inhibitory concentration 50% value of 7.7 +/- 1.4 nM in human T-47D breast cancer cells. Confocal fluorescence microscopy images of Alexa Fluor 680-G-G-G-BBN[7-14]NH(2) in human T-47D breast cancer cells indicated specific uptake, internalization, and receptor blocking of the fluorescent bioprobe in vitro. In vivo investigations in SCID mice bearing xenografted T-47D breast cancer lesions demonstrated the ability of this new conjugate to specifically target tumor tissue with high selectivity and affinity.

  13. Peptide Optical waveguides.

    PubMed

    Handelman, Amir; Apter, Boris; Shostak, Tamar; Rosenman, Gil

    2017-02-01

    Small-scale optical devices, designed and fabricated onto one dielectric substrate, create integrated optical chip like their microelectronic analogues. These photonic circuits, based on diverse physical phenomena such as light-matter interaction, propagation of electromagnetic waves in a thin dielectric material, nonlinear and electro-optical effects, allow transmission, distribution, modulation, and processing of optical signals in optical communication systems, chemical and biological sensors, and more. The key component of these optical circuits providing both optical processing and photonic interconnections is light waveguides. Optical confinement and transmitting of the optical waves inside the waveguide material are possible due to the higher refractive index of the waveguides in comparison with their surroundings. In this work, we propose a novel field of bionanophotonics based on a new concept of optical waveguiding in synthetic elongated peptide nanostructures composed of ordered peptide dipole biomolecules. New technology of controllable deposition of peptide optical waveguiding structures by nanofountain pen technique is developed. Experimental studies of refractive index, optical transparency, and linear and nonlinear waveguiding in out-of-plane and in-plane diphenylalanine peptide nanotubes have been conducted. Optical waveguiding phenomena in peptide structures are simulated by the finite difference time domain method. The advantages of this new class of bio-optical waveguides are high refractive index contrast, wide spectral range of optical transparency, large optical nonlinearity, and electro-optical effect, making them promising for new applications in integrated multifunctional photonic circuits. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  14. Positional scanning for peptide secondary structure by systematic solid-phase synthesis of amino lactam peptides.

    PubMed

    Jamieson, Andrew G; Boutard, Nicolas; Beauregard, Kim; Bodas, Mandar S; Ong, Huy; Quiniou, Christiane; Chemtob, Sylvain; Lubell, William D

    2009-06-10

    Incorporation of amino lactams into biologically active peptides has been commonly used to restrict conformational mobility, enhance selectivity, and increase potency. A solid-phase method using a Fmoc-protection strategy has been developed for the systematic synthesis of peptides containing configurationally defined alpha- and beta-amino gamma-lactams. N-Alkylation of N-silyl peptides with five- and six-member cyclic sulfamidates 9 and 8 minimized bis-alkylation and provided N-alkyl peptides, which underwent lactam annulation under microwave heating. Employing this solid-phase protocol on the growth hormone secretagogue GHRP-6, as well as on the allosteric modulator of the IL-1 receptor 101.10, has furnished 16 lactam derivatives and validated the effectiveness of this approach on peptides bearing aliphatic, aromatic, branched, charged, and heteroatomic side chains. The binding affinity IC(50) values of the GHRP-6 lactam analogues on both the GHS-R1a and CD36 receptors are reported as well as inhibition of thymocyte proliferation measurements for the 101.10 lactam analogues. In these cases, lactam analogues were prepared exhibiting similar or improved properties compared with the parent peptide. Considering the potential for amino lactams to induce peptide turn conformations, the effective method described herein for their supported construction on growing peptides, and for the systematical amino lactam scan of peptides, has proven useful for the rapid identification of the secondary structure necessary for peptide biological activity.

  15. Purification of radiolabeled RNA products using denaturing gel electrophoresis

    PubMed Central

    Adachi, Hironori; Yu, Yi-Tao

    2014-01-01

    This unit discusses a basic method for purification of radiolabeled RNAs using denaturing polyacrylamide gel electrophoresis. The method consists of a number of experimental procedures, including total RNA preparation from yeast cells, isolation of a specific RNA from total yeast RNA, RNA 3' terminal labeling using nucleotide (5’[32P]pCp) addition (via ligation), denaturing (8 M urea) polyacrylamide gel electrophoresis, and RNA extraction from the gel slice. Key points for achieving good electrophoretic separation of RNA are also discussed. PMID:24510465

  16. Localisation of malignant glioma by a radiolabelled human monoclonal antibody.

    PubMed Central

    Phillips, J; Alderson, T; Sikora, K; Watson, J

    1983-01-01

    Human monoclonal antibodies were produced by fusing intratumoral lymphocytes from patients with malignant gliomas with a human myeloma line. One antibody was selected for further study after screening for binding activity to glioma cell lines. The patient from whom it was derived developed recurrent glioma. 1 mg of antibody was purified, radiolabelled with 131I, and administered intravenously. The distribution of antibody was determined in the blood, CSF and tumour cyst fluid and compared with that of a control human monoclonal immunoglobulin. Antibody localisation in the tumour was observed and confirmed by external scintiscanning. Images PMID:6101173

  17. Development of a new bombesin analog radiolabeled with lutetium-177: in vivo evaluation of the biological properties in Balb-C mice.

    PubMed

    Pujatti, P B; Santos, J S; Massicano, A V F; Mengatti, J; De Araújo, E B

    2010-05-10

    In this work we describe the first results of radiolabeling with lutetium-177 ((177)Lu) and in vivo biodistribution and pharmacokinetics studies in normal Balb-c mice of a new bombesin analog (BEFG2)--DOTA-Phe-X-BBN(6-14), where X is a spacer of two aminoacids. Bombesin (BBN) is an amphibian analog of human gastrin releasing peptide (GRP). Development of radiolabeled BBN derivatives as agents for diagnostic imaging and systemic radiotherapy has increased considerable because of the observation that GRP receptors (GRPr) are over-expressed in a variety of human tumor cells, such as prostate tumor cells. (177)Lu-labeled peptides are attractive due to the excellent radiophysical properties and commercial availability of the radiometal. BEFG2 was successfully labeled with high yield and kept stable for more than 96 hours at 2-8 degrees C and 1 hour in human plasma. Data analysis obtained from the in vivo studies showed that the amount of BEFG2 present in plasma decreased rapidly and became almost undetectable at 60 min p.i., indicating rapid peptide excretion, which is performed mainly by renal pathway. In addition, biodistribution and single photon emission tomography showed low abdominal accumulation of (177)Lu-DOTA- Phe-X-BBN(6-14), indicating that this analog is a potential candidate for tumors target therapy.

  18. C-H activation: Complex peptides made simple

    NASA Astrophysics Data System (ADS)

    Bartlett, Sean; Spring, David R.

    2017-01-01

    Nature oxidizes biosynthetic intermediates into structurally and functionally diverse peptides. An iron-catalysed C-H oxidation mimics this approach in the lab, enabling chemists to synthesize structural analogues with ease.

  19. Dual-mode imaging with radiolabeled gold nanorods

    PubMed Central

    Agarwal, Ashish; Shao, Xia; Rajian, Justin R.; Zhang, Huanan; Chamberland, David L.; Kotov, Nicholas A.; Wang, Xueding

    2011-01-01

    Many nanoparticle contrast agents have difficulties with deep tissue and near-bone imaging due to limited penetration of visible photons in the body and mineralized tissues. We are looking into the possibility of mediating this problem while retaining the capabilities of the high spatial resolution associated with optical imaging. As such, the potential combination of emerging photoacoustic imaging and nuclear imaging in monitoring of antirheumatic drug delivery by using a newly developed dual-modality contrast agent is investigated. The contrast agent is composed of gold nanorods (GNRs) conjugated to the tumor necrosis factor (TNF-α) antibody and is subsequently radiolabeled by 125I. ELISA experiments designed to test TNF-α binding are performed to prove the specificity and biological activity of the radiolabeled conjugated contrast agent. Photoacoustic and nuclear imaging are performed to visualize the distribution of GNRs in articular tissues of the rat tail joints in situ. Findings from the two imaging modalities correspond well with each other in all experiments. Our system can image GNRs down to a concentration of 10 pM in biological tissues and with a radioactive label of 5 μCi. This study demonstrates the potential of combining photoacoustic and nuclear imaging modalities through one targeted contrast agent for noninvasive monitoring of drug delivery as well as deep and mineralized tissue imaging. PMID:21639567

  20. Radiolabeling and in vivo distribution of nanobacteria in rabbits

    NASA Astrophysics Data System (ADS)

    Akerman, Kari K.; Kuikka, Jyrki T.; Ciftcioglu, Neva; Parkkinen, Jyrki; Bergstroem, Kim A.; Kuronen, Ilpo; Kajander, E. Olavi

    1997-07-01

    Nanobacteria are minute bacteria recently isolated from mammalian blood. They encapsulate themselves with apatite mineral. Cultured nanobacteria were radiolabeled with (superscript 99m)Tc, using a method which has been previously used for labeling red blood cells with (superscript 99m)Tc, and in vivo distribution of nanobacteria was followed with Single Photon Emission Computed Tomography (SPECT) imaging. The labeling yield was over 30%. Two rabbits were studied using dynamic planar imaging performed in the AP-position immediately after injection. Serial SPECT scans were acquired up to 24 h and one planar image was taken at 45 h. A control study was performed administering a similar dose of [(superscript 99m)Tc] labeled albumin nanocolloids. Regional nanobacteria-to- nanocolloid ratios were calculated along with time and tissues (45 h) were analyzed for radioactivity and for nanobacteria. The main finding was that radiolabeled nanobacteria remained intact and showed a tissue specific distribution with a high accumulation in the kidneys and also in urine. Spleen, stomach, heart and intestine also showed increased uptake. Excretion into urine started 10 - 15 min after injection. These were live nanobacteria in the urine, which had better capabilities to penetrate into cells in vitro. The nanobacteria accessed the urine via tubular cells since nanobacteria were found in their cytoplasm and tubular surfaces. The results suggest that nanobacteria utilize endocytic transport of tubular cells and may be involved in the pathogenesis of mineral formation in mammalian kidney stones.

  1. Fusarinine C, a novel siderophore-based bifunctional chelator for radiolabeling with Gallium-68.

    PubMed

    Zhai, Chuangyan; Summer, Dominik; Rangger, Christine; Haas, Hubertus; Haubner, Roland; Decristoforo, Clemens

    2015-05-15

    Fusarinine C (FSC), a siderophore-based chelator coupled with the model peptide c(RGDfK) (FSC(succ-RGD)3), revealed excellent targeting properties in vivo using positron emission tomography (PET). Here, we report the details of radiolabeling conditions and specific activity as well as selectivity for (68)Ga. (68)Ga labeling of FSC(succ-RGD)3 was optimized regarding peptide concentration, pH, temperature, reaction time, and buffer system. Specific activity (SA) of [(68)Ga]FSC(succ-RGD)3 was compared with (68)Ga-1,4,7-triazacyclononane, 1-glutaric acid-4,7 acetic acid RGD ([(68)Ga]NODAGA-RGD). Stability was evaluated in 1000-fold ethylenediaminetetraacetic acid (EDTA) solution (pH 7) and phosphate-buffered saline (PBS). Metal competition tests (Fe, Cu, Zn, Al, and Ni) were carried out using [(68)Ga]-triacetylfusarinine C. High radiochemical yield was achieved within 5 min at room temperature, in particular allowing labeling with (68)Ga up to pH 8 with excellent stability in 1000-fold EDTA solution and PBS. The 10-fold to 20-fold lower concentrations of FSC(succ-RGD)3 led to the same radiochemical yield compared with [(68)Ga]NODAGA-RGD with SA up to 1.8 TBq/µmol. Metal competition tests showed high selective binding of (68)Ga to FSC. FSC is a multivalent siderophore-based bifunctional chelator allowing fast and highly selective labeling with (68)Ga in a wide pH range and results in stable complexes with high SA. Thus it is exceptionally well suited for the development of new (68)Ga-tracers for in vivo molecular imaging with PET.

  2. Peptides and peptidomimetics in medicine, surgery and biotechnology.

    PubMed

    Gentilucci, Luca; Tolomelli, Alessandra; Squassabia, Federico

    2006-01-01

    Despite the fact that they have been used for a century to treat several kinds of diseases, peptides and short proteins are now considered the new generation of biologically active tools. Indeed, recent findings suggest a wide range of novel applications in medicine, biotechnology, and surgery. The efficacy of native peptides has been greatly enhanced by introducing structural modifications in the original sequences, giving rise to the class of peptidomimetics. This review gives an overview of both classical applications and promising new categories of biologically active peptides and analogs. Besides the new entries in well known peptide families, such as antibiotic macrocyclic peptides, integrin inhibitors, as well as immunoactive, anticancer, neuromodulator, opioid, and hormone peptides, a number of novel applications have been recently reported. Outstanding examples include peptide-derived semi-synthetic vaccines, drug delivery systems, radiolabeled peptides, self-assembling peptides, which can serve as biomaterials in tissue engineering for creating cartilage, blood vessels, and other tissues, or as substrates for neurite outgrowth and synapse formation, immobilized peptides, and proteins. Finally, peptide-based biomaterials can find applications in bio-nanotechnology for bio-microchips, peptide nanorods and nanotubes, bio-sensors, bio-electronic devices, and peptide-metal wires.

  3. Quantitative autoradiographic mapping of focal herpes simplex virus encephalitis using a radiolabeled antiviral drug

    SciTech Connect

    Price, R.

    1984-12-18

    A method of mapping herpes simplex viral infection comprising administering a radiolabeled antiviral active 5-substituted 1-(2'-deoxy-2'-substituted-D-arabinofuranosyl) pyrimidine nucleoside to the infected subject, and scanning the area in which the infection is to be mapped for the radiolabel.

  4. Aspartame and Its Analogues

    NASA Astrophysics Data System (ADS)

    Pavlova, L. A.; Komarova, T. V.; Davidovich, Yurii A.; Rogozhin, S. V.

    1981-04-01

    The results of studies on the biochemistry of the sweet taste are briefly reviewed. The methods of synthesis of "aspartame" — a sweet dipeptide — are considered, its structural analogues are described, and quantitative estimates are made of the degree of sweetness relative to sucrose. Attention is concentrated mainly on problems of the relation between the structure of the substance and its taste in the series of aspartyl derivatives. The bibliography includes 118 references.

  5. Quantum analogue computing.

    PubMed

    Kendon, Vivien M; Nemoto, Kae; Munro, William J

    2010-08-13

    We briefly review what a quantum computer is, what it promises to do for us and why it is so hard to build one. Among the first applications anticipated to bear fruit is the quantum simulation of quantum systems. While most quantum computation is an extension of classical digital computation, quantum simulation differs fundamentally in how the data are encoded in the quantum computer. To perform a quantum simulation, the Hilbert space of the system to be simulated is mapped directly onto the Hilbert space of the (logical) qubits in the quantum computer. This type of direct correspondence is how data are encoded in a classical analogue computer. There is no binary encoding, and increasing precision becomes exponentially costly: an extra bit of precision doubles the size of the computer. This has important consequences for both the precision and error-correction requirements of quantum simulation, and significant open questions remain about its practicality. It also means that the quantum version of analogue computers, continuous-variable quantum computers, becomes an equally efficient architecture for quantum simulation. Lessons from past use of classical analogue computers can help us to build better quantum simulators in future.

  6. Aspects of monitoring and quality assurance for radiolabeled antibodies

    SciTech Connect

    Barber, D.E. . School of Public Health)

    1992-06-01

    This report provides an informational resource and guide for the US Nuclear Regulatory Commission (NRC) and NRC licensees who produce or use radiolabeled antibodies (RABs). Components of quality assurance programs related to the production and use of RABs are reviewed and evaluated, and recommendations are made on dosage calibrations, exposure control, monitoring, and personnel requirements. Special emphasis is placed on dose calibrators because these instruments are used extensively to measure the dosage of radiopharmaceuticals to be administered to patients. The difficulties of using dose calibrators to quantify dosages of beta- and alpha-emitters are discussed. The advantages and disadvantages of using other instruments are examined, and recommendations are made on the types of instruments to be used for different applications. 46 refs., 8 tabs.

  7. Isolation of radiolabeled isoflavones from kudzu (Pueraria lobata) root cultures.

    PubMed

    Reppert, Adam; Yousef, Gad G; Rogers, Randy B; Lila, Mary Ann

    2008-09-10

    Isoflavones have potential for preventing and treating several chronic health conditions, such as osteoporosis, cardiovascular disease, and cancer. In this study, radiolabeled isoflavones were recovered from kudzu (Pueraria lobata) root cultures after incubation with uniformly labeled (14)C-sucrose in the culture medium for 21 days. Approximately 19% of administered label was recovered in the isoflavone-rich dried extracts of kudzu root cultures (90.2 microCi/g or 3.3 MBq/g extract). HPLC-PDA analysis revealed the predominant isoflavones isolated from kudzu root cultures to be puerarin, daidzin, and malonyl-daidzin. The average concentration of the major isoflavone puerarin in kudzu root cultures was 33.6 mg/g extract, with a specific activity of 63.5 microCi/g (2.3 MBq/g). The isolated isoflavones were sufficiently (14)C-labeled to permit utilization for subsequent in vivo metabolic tracking studies.

  8. Isolation of Radiolabeled Isoflavones from Kudzu (Pueraria lobata) Root Cultures

    PubMed Central

    Reppert, Adam; Yousef, Gad G.; Rogers, Randy B.; Lila, Mary Ann

    2009-01-01

    Isoflavones have potential for preventing and treating several chronic health conditions, such as osteoporosis, cardiovascular disease, and cancer. In this study, radiolabeled isoflavones were recovered from kudzu (Pueraria lobata) root cultures after incubation with uniformly labeled 14C-sucrose in the culture medium for 21 days. Approximately 19% of administered label was recovered in the isoflavone-rich dried extracts of kudzu root cultures (90.2 μCi/g or 3.3 MBq/g extract). HPLC-PDA analysis revealed the predominant isoflavones isolated from kudzu root cultures to be puerarin, daidzin, and malonyl-daidzin. The average concentration of the major isoflavone puerarin in kudzu root cultures was 33.6 mg/g extract, with a specific activity of 63.5 μCi/g (2.3 MBq/g). The isolated isoflavones were sufficiently 14C-labeled to permit utilization for subsequent in vivo metabolic tracking studies PMID:18690681

  9. Radiolabeling of Nanoparticles and Polymers for PET Imaging

    PubMed Central

    Stockhofe, Katharina; Postema, Johannes M.; Schieferstein, Hanno; Ross, Tobias L.

    2014-01-01

    Nanomedicine has become an emerging field in imaging and therapy of malignancies. Nanodimensional drug delivery systems have already been used in the clinic, as carriers for sensitive chemotherapeutics or highly toxic substances. In addition, those nanodimensional structures are further able to carry and deliver radionuclides. In the development process, non-invasive imaging by means of positron emission tomography (PET) represents an ideal tool for investigations of pharmacological profiles and to find the optimal nanodimensional architecture of the aimed-at drug delivery system. Furthermore, in a personalized therapy approach, molecular imaging modalities are essential for patient screening/selection and monitoring. Hence, labeling methods for potential drug delivery systems are an indispensable need to provide the radiolabeled analog. In this review, we describe and discuss various approaches and methods for the labeling of potential drug delivery systems using positron emitters. PMID:24699244

  10. Use of radiolabeled acetate to evaluate the rate of clearance of cerebral oxidative metabolites

    SciTech Connect

    Lear, J.L.; Kasliwal, R.; Duryea, R.A.

    1994-05-01

    Radiolabel derived from glucose (GLC) has been shown to have different cerebral retention kinetics than radiolabel derived from deoxyglucose (DG). In particular, activated structures with high metabolic rates have more rapid loss of GLC-derived radiolabel than DG-derived radiolabel. Because GLC-derived radiolabel can be lost from the brain glycolytically through lactate or oxidatively through CO{sub 2}, the cause of the difference between GLC and FDG is uncertain. We investigated the isolated oxidative pathway using radiolabeled acetate, which is only metabolized through the Krebs cycle. Male albino rats were anesthetized with halothane and femoral vein and artery catheters were placed. The rats were allowed to awaken for two hours prior to the studies. 100 uCi of {sup 14}C-acetate was administered as a 30 second IV infusion to each rat. Arterial samples were obtained at regular intervals. Groups of rats were killed at 5, 10, 15, 30, and 60 minutes. Brains were rapidly removed, sectioned, and used to produce autoradiograms. The extracted and retained radiolabel was calculated as the brain concentration at time of death divided by the integral of the arterial tracer concentration. No detectable loss of radiolabel was found over the initial 10 minutes. Thereafter the rate of loss gradually increased reaching a maximum of 1.2% per minute by 60 minutes. This corresponds to a k4 rate constant of 0.012 min{sup -1}. The rate of loss of oxidative metabolites from rat brain was found to be very slow. This probably results from exchange of radiolabel with amino acid pools as the tracer is metabolized through the Krebs cycle. Therefore in conditions were glycolysis is increased out of proportion to oxidation and cerebral lactate concentration rises, radiolabel loss through lactate efflux can be a substantial fraction of overall loss.

  11. Interaction of a radiolabeled agonist with cardiac muscarinic cholinergic receptors

    SciTech Connect

    Harden, T.K.; Meeker, R.B.; Martin, M.W.

    1983-12-01

    The interaction of a radiolabeled muscarinic cholinergic receptor agonist, (methyl-/sup 3/H)oxotremorine acetate ((/sup 3/H)OXO), with a washed membrane preparation derived from rat heart, has been studied. In binding assays at 4 degrees C, the rate constants for association and dissociation of (/sup 3/H)OXO were 2 X 10(7) M-1 min-1 and 5 X 10(-3) min-1, respectively, Saturation binding isotherms indicated that binding was to a single population of sites with a Kd of approximately 300 pM. The density of (/sup 3/H)OXO binding sites (90-100 fmol/mg of protein) was approximately 75% of that determined for the radiolabeled receptor antagonist (/sup 3/H)quinuclidinyl benzilate. Both muscarinic receptor agonists and antagonists inhibited the binding of (/sup 3/H)OXO with high affinity and Hill slopes of approximately one. Guanine nucleotides completely inhibited the binding of (/sup 3/H)OXO. This effect was on the maximum binding (Bmax) of (/sup 3/H)OXO with no change occurring in the Kd; the order of potency for five nucleotides was guanosine 5'-O-(3-thio-triphosphate) greater than 5'-guanylylimidodiphosphate greater than GTP greater than or equal to guanosine/diphosphate greater than GMP. The (/sup 3/H)OXO-induced interaction of muscarinic receptors with a guanine nucleotide binding protein was stable to solubilization. That is, membrane receptors that were prelabeled with (/sup 3/H)OXO could be solubilized with digitonin, and the addition of guanine nucleotides to the soluble, (/sup 3/H)OXO-labeled complex resulted in dissociation of (/sup 3/H)OXO from the receptor. Pretreatment of membranes with relatively low concentrations of N-ethylmaleimide inhibited (/sup 3/H)OXO binding by 85% with no change in the Kd of (/sup 3/H)OXO, and with no effect on (/sup 3/H)quinuclidinyl benzilate binding.

  12. Intravesical administration of radiolabeled antitumor monoclonal antibody in bladder carcinoma

    SciTech Connect

    Bamias, A.; Keane, P.; Krausz, T.; Williams, G.; Epenetos, A.A. )

    1991-01-15

    Tumor associated AUA1 monoclonal antibody and 11.4.1. nonspecific monoclonal antibody, which does not react with human tissues, were radiolabeled with 111In and administered intravesically to 23 patients undergoing cystoscopy for bladder carcinoma. The antibody solution remained in the bladder for 1 h and then was washed out prior to cystoscopy. Tumor and nontumor samples were obtained during cystoscopy and were counted in a gamma counter. Conventional and immunoperoxidase staining with both antibodies were also performed. AUA1 reacted with all bladder carcinomas while 11.4.1. was negative in all cases. The mean uptake of AUA1 at 2, 24, and 48 h after the instillation (expressed as 10(3) x percentage of injected dose/g of tissue) was: 6.12 +/- 5.50 (SD), 1.70 +/- 2.57, 0.30 +/- 0.17 in the tumors and 0.32 +/- 0.50, 0.22 +/- 0.30, 0 in the nontumor areas, and for 11.4.1. it was: 0.075 +/- 0.075, 0.025 +/- 0.025 in the tumors and 0.30 +/- 0.42, 0.15 +/- 0.26 in the nontumor areas. The uptake of AUA1 by the tumors correlated with the tumor grade. There was no radioactivity in the blood at 2 h, and at 1, 2, and 3 days after the instillation. Our results indicate that intravesical administration of radiolabeled monoclonal antibody AUA1 targets selectively to tumor tissue without any significant normal tissue uptake. This finding might allow the development of a nontoxic and specific therapeutic approach for superficial bladder carcinoma.

  13. Further insights into brevetoxin metabolism by de novo radiolabeling.

    PubMed

    Calabro, Kevin; Guigonis, Jean-Marie; Teyssié, Jean-Louis; Oberhänsli, François; Goudour, Jean-Pierre; Warnau, Michel; Bottein, Marie-Yasmine Dechraoui; Thomas, Olivier P

    2014-06-10

    The toxic dinoflagellate Karenia brevis, responsible for early harmful algal blooms in the Gulf of Mexico, produces many secondary metabolites, including potent neurotoxins called brevetoxins (PbTx). These compounds have been identified as toxic agents for humans, and they are also responsible for the deaths of several marine organisms. The overall biosynthesis of these highly complex metabolites has not been fully ascertained, even if there is little doubt on a polyketide origin. In addition to gaining some insights into the metabolic events involved in the biosynthesis of these compounds, feeding studies with labeled precursors helps to discriminate between the de novo biosynthesis of toxins and conversion of stored intermediates into final toxic products in the response to environmental stresses. In this context, the use of radiolabeled precursors is well suited as it allows working with the highest sensitive techniques and consequently with a minor amount of cultured dinoflagellates. We were then able to incorporate [U-¹⁴C]-acetate, the renowned precursor of the polyketide pathway, in several PbTx produced by K. brevis. The specific activities of PbTx-1, -2, -3, and -7, identified by High-Resolution Electrospray Ionization Mass Spectrometer (HRESIMS), were assessed by HPLC-UV and highly sensitive Radio-TLC counting. We demonstrated that working at close to natural concentrations of acetate is a requirement for biosynthetic studies, highlighting the importance of highly sensitive radiolabeling feeding experiments. Quantification of the specific activity of the four, targeted toxins led us to propose that PbTx-1 and PbTx-2 aldehydes originate from oxidation of the primary alcohols of PbTx-7 and PbTx-3, respectively. This approach will open the way for a better comprehension of the metabolic pathways leading to PbTx but also to a better understanding of their regulation by environmental factors.

  14. Orientation Preferences of Backbone Secondary Amide Functional Groups in Peptide Nucleic Acid Complexes: Quantum Chemical Calculations Reveal an Intrinsic Preference of Cationic D-Amino Acid-Based Chiral PNA Analogues for the P-form

    SciTech Connect

    Smith, Jeremy C; Topham, Christopher

    2007-01-01

    Geometric descriptions of nonideal interresidue hydrogen bonding and backbone-base water bridging in the minor groove are established in terms of polyamide backbone carbonyl group orientation from analyses of residue junction conformers in experimentally determined peptide nucleic acid (PNA) complexes. Two types of interresidue hydrogen bonding are identified in PNA conformers in heteroduplexes with nucleic acids that adopt A-like base pair stacking. Quantum chemical calculations on the binding of a water molecule to an O2 base atom in glycine-based PNA thymine dimers indicate that junctions modeled with P-form backbone conformations are lower in energy than a dimer comprising the predominant conformation observed in A-like helices. It is further shown in model systems that PNA analogs based on D-lysine are better able to preorganize in a conformation exclusive to P-form helices than is glycine-based PNA. An intrinsic preference for this conformation is also exhibited by positively charged chiral PNA dimers carrying 3-amino-D-alanine or 4-aza-D-leucine residue units that provide for additional rigidity by side-chain hydrogen bonding to the backbone carbonyl oxygen. Structural modifications stabilizing P-form helices may obviate the need for large heterocycles to target DNA pyrimidine bases via PNADNA-PNA triplex formation. Quantum chemical modeling methods are used to propose candidate PNA Hoogsteen strand designs.

  15. Clinical uses of gut peptides.

    PubMed Central

    Geoghegan, J; Pappas, T N

    1997-01-01

    OBJECTIVE: The authors review clinical applications of gut-derived peptides as diagnostic and therapeutic agents. SUMMARY BACKGROUND DATA: An increasing number of gut peptides have been evaluated for clinical use. Earlier uses as diagnostic agents have been complemented more recently by increasing application of gut peptides as therapeutic agents. METHOD: The authors conducted a literature review. RESULTS: Current experience with clinical use of gut peptides is described. Initial clinical applications focused on using secretomotor effects of gut peptides in diagnostic tests, many of which have now fallen into disuse. More recently, attention has been directed toward harnessing these secretomotor effects for therapeutic use in a variety of disorders, and also using the trophic effects of gut peptides to modulate gut mucosal growth in benign and malignant disease. Gut peptides have been evaluated in a variety of other clinical situations including use as adjuncts to imaging techniques, and modification of behaviors such as feeding and panic disorder. CONCLUSIONS: Gut peptides have been used successfully in an increasing variety of clinical conditions. Further refinements in analogue and antagonist design are likely to lead to even more selective agents that may have important clinical applications. Further studies are needed to identity and evaluate these new agents. PMID:9065291

  16. Biological activity of silylated amino acid containing substance P analogues.

    PubMed

    Cavelier, F; Marchand, D; Martinez, J; Sagan, S

    2004-03-01

    The need to replace natural amino acids in peptides with nonproteinogenic counterparts to obtain new medicinal agents has stimulated a great deal of innovation on synthetic methods. Here, we report the incorporation of non-natural silylated amino acids in substance P (SP), the binding affinity for the two hNK-1 binding sites and, the potency to stimulate phospholipase C (PLC) and adenylate cyclase of the resulting peptide. We also assess the improvement of their stability towards enzyme degradation. Altogether, we found that replacing glycine with silaproline (Sip) in position 9 of SP leads to a potent analogue exhibiting an increased resistance to angiotensin-converting enzyme hydrolysis.

  17. The prognostic influence of the proliferative discordance in metastatic pancreatic neuroendocrine carcinoma revealed by peptide receptor radionuclide therapy

    PubMed Central

    Montanier, Nathanaëlle; Joubert-Zakeyh, Juliette; Pétorin, Caroline; Montoriol, Pierre François; Maqdasy, Salwan; Kelly, Antony

    2017-01-01

    Abstract Rationale: Pancreatic neuroendocrine tumors (pNET) are rare slowly growing tumors with a high metastatic potential. Peptide receptor radionuclide therapy (PRRT) with radiolabeled analogues has been developed as a new tool for the management of metastatic well-differentiated (grade 1 and 2) neuroendocrine tumors expressing somatostatin receptor (SSTR2). Chemotherapy is the mainstay in the management of grade 3 (G3) unresectable pancreatic neuroendocrine carcinoma (pNEC). To date, no study has evaluated the efficacy of PRRT in such tumors. Diagnoses and interventions: We describe a case of a progressive G3 pNEC with huge liver metastases successfully treated with PRRT (177Lu DOTATATE). Outcomes: Complete remission was obtained for 3 years. Indeed, the mitotic index was low (as G2 tumors) but with a very high Ki-67 index (45%–70%). Such discordance between the proliferative markers should consider the use of PRRT before chemotherapy in unresectable metastatic G3 tumors expressing SSTR2. Lessons: This case supports the hypotheses highlighting the heterogeneity of G3 pNEC. The latter should be subdivided into 2 distinct categories: proliferation-discordant (well differentiated) and concordant (poorly differentiated) NEC. PRRT could be suggested for the former group before the conventional chemotherapy. PMID:28178157

  18. Radiolabeled cyclic arginine-glycine-aspartic (RGD)-conjugated iron oxide nanoparticles as single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) dual-modality agents for imaging of breast cancer

    NASA Astrophysics Data System (ADS)

    Deng, Shengming; Zhang, Wei; Zhang, Bin; Hong, Ruoyu; Chen, Qing; Dong, Jiajia; Chen, Yinyiin; Chen, Zhiqiang; Wu, Yiwei

    2015-01-01

    Ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) modified with a novel cyclic arginine-glycine-aspartate (RGD) peptide were made and radiolabeled as single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) dual-modality agents for imaging of breast cancer. The probe was tested both in vitro and in vivo to determine its receptor targeting efficacy and feasibility for SPECT and MRI. The radiochemical syntheses of 125I-cRGD-USPIO were accomplished with a radiochemical purity of 96.05 ± 0.33 %. High radiochemical stability was found in fresh human serum and in phosphate-buffered saline. The average hydrodynamic size of 125I-cRGD-USPIO determined by dynamic light scattering was 51.3 nm. Results of in vitro experiments verified the specificity of the radiolabeled nanoparticles to tumor cells. Preliminary biodistribution studies of 125I-radiolabeled cRGD-USPIO in Bcap37-bearing nude mice showed that it had long circulation half-life, high tumor uptake, and high initial blood retention with moderate liver uptake. In vivo tumor targeting and uptake of the radiolabeled nanoparticles in mice model were visualized by SPECT and MRI collected at different time points. Our results strongly indicated that the 125I-cRGD-USPIO could be used as a promising bifunctional radiotracer for early clinical tumor detection with high sensitivity and high spatial resolution by SPECT and MRI.

  19. Analogues of arginine vasopressin modified in position 2 and 3 with conformationally constrained dipeptide fragments.

    PubMed

    Łempicka, Elzbieta; Derdowska, Izabela; Kowalczyk, Wioleta; Dawidowska, Olga; Prahl, Adam; Janecki, Marcin; Jasiński, Tomasz; Trzeciak, Henryk I; Lammek, Bernard

    2005-02-01

    This study describes the synthesis and some pharmacological properties of ten new analogues of arginine vasopressin (AVP) containing a conformationally constrained dipeptide fragment in the N-terminal part of their molecules. Amino acid residues in positions 2 and 3 of AVP and some of its agonistic analogues were replaced with -Phe-Phe and D-Phe-D-Phe, dipeptides having a -CH2-CH2- link bridging two nitrogens. All the new peptides were tested for vasopressor and antidiuretic activities. Four peptides with pA2 values ranging from 5.96 to 7.21 turned out to be weak or moderately potent V1a antagonists. The results supplied new information about the structure-activity relationship of AVP analogues. As some of these were unexpected, they point to the need for caution when extrapolating previously known effects of modifications to analogues having conformationally constrained fragments in their molecules.

  20. Investigations on the Ga(III) Complex of EOB-DTPA and Its 68Ga Radiolabeled Analogue.

    PubMed

    Greiser, Julia; Niksch, Tobias; Weigand, Wolfgang; Freesmeyer, Martin

    2016-08-17

    We demonstrate a method for the isolation of EOB-DTPA (3,6,9-triaza-3,6,9-tris(carboxymethyl)-4-(ethoxybenzyl)-undecanedioic acid) from its Gd(III) complex and protocols for the preparation of its novel non-radioactive, i.e., natural Ga(III) as well as radioactive (68)Ga complex. The ligand as well as the Ga(III) complex were characterized by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and elemental analysis. (68)Ga was obtained by a standard elution method from a (68)Ge/(68)Ga generator. Experiments to evaluate the (68)Ga-labeling efficiency of EOB-DTPA at pH 3.8-4.0 were performed. Established analysis techniques radio TLC (thin layer chromatography) and radio HPLC (high performance liquid chromatography) were used to determine the radiochemical purity of the tracer. As a first investigation of the (68)Ga tracers' lipophilicity the n-octanol/water distribution coefficient of (68)Ga species present in a pH 7.4 solution was determined by an extraction method. In vitro stability measurements of the tracer in various media at physiological pH were performed, revealing different rates of decomposition.

  1. Evidence that transporters associated with antigen processing translocate a major histocompatibility complex class I-binding peptide into the endoplasmic reticulum in an ATP-dependent manner.

    PubMed Central

    Androlewicz, M J; Anderson, K S; Cresswell, P

    1993-01-01

    We have investigated the role of the putative peptide transporters associated with antigen processing (TAP) by using a permeabilized-cell system. The main objective was to determine whether these molecules, which bear homology to the ATP-binding cassette family of transporters, translocate antigenic peptides across the endoplasmic reticulum membrane for assembly with major histocompatibility complex (MHC) class I molecules and beta 2-microglobulin light chain. The pore-forming toxin streptolysin O was used to generate permeabilized cells, and peptide translocation was determined by measuring the amount of added radiolabeled peptide bound to endogenous class I molecules. No radiolabeled peptide was associated with MHC class I glycoproteins from unpermeabilized cells. We found that efficient peptide binding to MHC class I molecules in permeabilized cells is both transporter dependent and ATP dependent. In antigen-processing mutant cells lacking a functional transporter, uptake occurs only through a less-efficient transporter and ATP-independent pathway. In addition, short peptides (8-10 amino acids) known to bind MHC class I molecules compete efficiently with a radiolabeled peptide for TAP-dependent translocation, whereas longer peptides and a peptide derived from an endoplasmic reticulum signal sequence do not compete efficiently. This result indicates that the optimal substrates for TAP possess the characteristics of MHC-binding peptides. Images Fig. 2 Fig. 3 Fig. 4 PMID:8415666

  2. Optimising the radiolabelling properties of technetium tricarbonyl and His-tagged proteins

    PubMed Central

    2014-01-01

    Background To date, the majority of protein-based radiopharmaceuticals have been radiolabelled using non-site-specific conjugation methods, with little or no control to ensure retained protein function post-labelling. The incorporation of a hexahistidine sequence (His-tag) in a recombinant protein can be used to site-specifically radiolabel with 99mTc-tricarbonyl ([99mTc(CO)3]+). This chemistry has been made accessible via a technetium tricarbonyl kit; however, reports of radiolabelling efficiencies and specific activities have varied greatly from one protein to another. Here, we aim to optimise the technetium tricarbonyl radiolabelling method to produce consistently >95% radiolabelling efficiencies with high specific activities suitable for in vivo imaging. Methods Four different recombinant His-tagged proteins (recombinant complement receptor 2 (rCR2) and three single chain antibodies, α-CD33 scFv, α-VCAM-1 scFv and α-PSMA scFv), were used to study the effect of kit volume, ionic strength, pH and temperature on radiolabelling of four proteins. Results We used 260 and 350 μL [99mTc(CO)3]+ kits enabling us to radiolabel at higher [99mTc(CO)3]+ and protein concentrations in a smaller volume and thus increase the rate at which maximum labelling efficiency and specific activity were reached. We also demonstrated that increasing the ionic strength of the reaction medium by increasing [Na+] from 0.25 to 0.63 M significantly increases the rate at which all four proteins reach a >95% labelling efficiency by at least fourfold, as compared to the conventional IsoLink® kit (Covidien, Petten, The Netherlands) and 0.25 M [Na+]. Conclusion We have found optimised kit and protein radiolabelling conditions suitable for the reproducible, fast, efficient radiolabelling of proteins without the need for post-labelling purification. PMID:24606843

  3. Diversity-Oriented Peptide Stapling: A Third Generation Copper-Catalysed Azide-Alkyne Cycloaddition Stapling and Functionalisation Strategy.

    PubMed

    Tran, Phuong Thu; Larsen, Christian Ørnbøl; Røndbjerg, Tobias; De Foresta, Martina; Kunze, Micha B A; Marek, Ales; Løper, Jacob Hartvig; Boyhus, Lotte-Emilie; Knuhtsen, Astrid; Lindorff-Larsen, Kresten; Pedersen, Daniel Sejer

    2017-01-20

    The introduction of macrocyclic constraints in peptides (peptide stapling) is an important tool within peptide medicinal chemistry for stabilising and pre-organising peptides in a desired conformation. In recent years, the copper-catalysed azide-alkyne cycloaddition (CuAAC) has emerged as a powerful method for peptide stapling. However, to date CuAAC stapling has not provided a simple method for obtaining peptides that are easily diversified further. In the present study, we report a new diversity-oriented peptide stapling (DOPS) methodology based on CuAAC chemistry. Stapling of peptides incorporating two azide-modified amino acids with 1,3,5-triethynylbenzene efficiently provides (i, i+7)- and (i, i+9)-stapled peptides with a single free alkyne positioned on the staple, which can be further conjugated or dimerised. A unique feature of the present method is that it provides easy access to radiolabelled stapled peptides by catalytic tritiation of the alkyne positioned on the staple.

  4. Specific recognition of a tetrahedral phosphonamidate transition state analogue group by a recombinant antibody Fab fragment.

    PubMed

    Hua, T D; Lamaty, F; Souriau, C; Rolland-Fulcrand, V; Lazaro, R; Viallefont, P; Lefranc, M P; Weill, M

    1996-06-01

    In order to obtain antibodies able to catalyse a peptide synthesis, a naive combinatorial library of human Fab antibody fragments was screened with the phosphonamidate transition state analogue of the reaction. Several Fab fragments were able to bind the analogue. Competitive binding studies performed with molecules containing representative parts of the hapten showed that two Fabs were able to recognize specifically the tetrahedral phosphorus present in the hapten.

  5. Improved 18F Labeling of Peptides with a Fluoride-Aluminum-Chelate Complex

    PubMed Central

    McBride, William J.; D’Souza, Christopher A.; Sharkey, Robert M.; Karacay, Habibe; Rossi, Edmund A.; Chang, Chien-Hsing; Goldenberg, David M.

    2010-01-01

    We reported previously the feasibility to radiolabel peptides with fluorine-18 (18F) using a rapid, one-pot, method that first mixes 18F− with Al3+, and then binds the (Al18F)2+ complex to a NOTA ligand on the peptide. In this report, we examined several new NOTA ligands and determined how temperature, reaction time, and reagent concentration affected the radiolabeling yield. Four structural variations of the NOTA ligand had isolated radiolabeling yields ranging from 5.8% to 87% under similar reaction conditions. All of the Al18F NOTA complexes were stable in vitro in human serum and those that were tested in vivo also were stable. The radiolabeling reactions were performed at 100°C and the peptides could be labeled in as little as five minutes. The IMP467 peptide could be labeled up to 115 GBq/μmol (3100 Ci/mmol), with a total reaction and purification time of 30 min without chromatographic purification. PMID:20540570

  6. Measurement of MHC/Peptide Interactions by Gel Filtration or Monoclonal Antibody Capture

    PubMed Central

    Sidney, John; Southwood, Scott; Moore, Carrie; Oseroff, Carla; Pinilla, Clemencia; Grey, Howard M.; Sette, Alessandro

    2013-01-01

    This unit describes a technique for the direct and quantitative measurement of the capacity of peptide ligands to bind Class I and Class II MHC molecules. The binding of a peptide of interest to MHC is assessed based on its ability to inhibit the binding of a radiolabeled probe peptide to purified MHC molecules. This unit includes protocols for the purification of Class I and Class II MHC molecules by affinity chromatography, and for the radiolabeling of peptides using the chloramine T method. An alternate protocol describes alterations in the basic protocol that are necessary when performing direct binding assays, which are required for (1) selecting appropriate high-affinity, assay-specific, radiolabeled ligands, and (2) determining the amount of MHC necessary to yield assays with the highest sensitivity. After a predetermined incubation period, dependent upon the allele under examination, the bound and unbound radiolabeled species are separated, and their relative amounts are determined. Three methods for separation are described, two utilizing size-exclusion gel-filtration chromatography and a third using monoclonal antibody capture of MHC. Data analysis for each method is also explained. PMID:23392640

  7. Analogue-to-Digital and Digital-to-Analogue Conversion.

    ERIC Educational Resources Information Center

    Gregory, Martin

    1997-01-01

    Discusses circuits for three-bit and four-bit analogue digital converters and digital analogue converters. These circuits feature slow operating speeds that enable the circuitry to be used to demonstrate the mode of operation using oscilloscopes and signal generators. (DDR)

  8. Direct radiolabeling of antibody against stage specific embryonic antigen for diagnostic imaging

    DOEpatents

    Rhodes, B.A.

    1994-09-13

    Antibodies against stage specific embryonic antigen-1 is radiolabeled by direct means with a radionuclide for use in detection of occult abscess and inflammation. Radiolabeling is accomplished by partial reduction of the disulfide bonds of the antibody using Sn(II), or using other reducing agents followed by the addition of Sn(II), removal of excess reducing agent and reduction by-products, and addition of a specified amount of radionuclide reducing agent, such as stannous tartrate. The resulting product may be stored frozen or lyophilized, with radiolabeling accomplished by the addition of the radionuclide. No Drawings

  9. Direct radiolabeling of antibody against stage specific embryonic antigen for diagnostic imaging

    DOEpatents

    Rhodes, Buck A.

    1994-01-01

    Antibody against stage specific embryonic antigen-1 is radiolabeled by direct means with a radionuclide for use in detection of occult abscess and inflammation. Radiolabeling is accomplished by partial reduction of the disulfide bonds of the antibody using Sn(II), or using other reducing agents followed by the addition of Sn(II), removal of excess reducing agent and reduction by-products, and addition of a specified amount of radionuclide reducing agent, such as stannous tartrate. The resulting product may be store frozen or lyophilized, with radiolabeling accomplished by the addition of the radionuclide.

  10. Distribution and binding of 18F-labeled and 125I-labeled analogues of ACI-80, a prospective molecular imaging biomarker of disease: a whole hemisphere post mortem autoradiography study in human brains obtained from Alzheimer's disease patients.

    PubMed

    Gulyás, Balázs; Spenger, Christian; Beliczai, Zsuzsa; Gulya, Károly; Kása, Péter; Jahan, Mahabuba; Jia, Zhisheng; Weber, Urs; Pfeifer, Andrea; Muhs, Andreas; Willbold, Dieter; Halldin, Christer

    2012-01-01

    One of the major pathological landmarks of Alzheimer's disease and other neurodegenerative diseases is the presence of amyloid deposits in the brain. The early non-invasive visualization of amyloid is a major objective of recent diagnostic neuroimaging approaches, including positron emission tomography (PET), with an eye on follow-up of disease progression and/or therapy efficacy. The development of molecular imaging biomarkers with binding affinity to amyloid in the brain is therefore in the forefront of imaging biomarker and radiochemistry research. Recently, a dodecamer peptide (amino acid sequence=QSHYRHISPAQV; denominated D1 or ACI-80) was identified as a prospective ligand candidate, binding with high ex vivo affinity to L-Aβ-amyloid (K(d): 0.4 μM). In order to assess the ligand's capacity to visualize amyloid in Alzheimer's disease (AD), two (125)I labeled and three (18)F labeled analogues of the peptide were synthesized and tested in post mortem human autoradiography experiments using whole hemisphere brain slices obtained from deceased AD patients and age matched control subjects. The (18)F-labeled radioligands showed more promising visualization capacity of amyloid that the (125)I-labeled radioligands. In the case of each (18)F radioligands the grey matter uptake in the AD brains was significantly higher than that in control brains. Furthermore, the grey matter: white matter uptake ratio was over ~2, the difference being significant for each (18)F-radioligands. The regional distribution of the uptake of the various radioligands systematically shows a congruent pattern between the high uptake regions and spots in the autoradiographic images and the disease specific signals obtained in adjacent or identical brain slices labeled with histological, immunohistochemical or autoradiographic stains for amyloid deposits or activated astrocytes. The present data, using post mortem human brain autoradiography in whole hemisphere human brains obtained from deceased

  11. Quantification of β-Cell Mass in Intramuscular Islet Grafts Using Radiolabeled Exendin-4

    PubMed Central

    Espes, Daniel; Selvaraju, Ramkumar; Velikyan, Irina; Krajcovic, Martin; Carlsson, Per-Ola; Eriksson, Olof

    2016-01-01

    Background There is an increasing interest in alternative implantation sites to the liver for islet transplantation. Intramuscular implantation has even been tested clinically. Possibilities to monitor β-cell mass would be of huge importance not only for the understanding of islet engraftment but also for the decision of changing the immunosuppressive regime. We have therefore evaluated the feasibility of quantifying intramuscular β-cell mass using the radiolabeled glucagon like peptide-1 receptor agonist DO3A-VS-Cys40-Exendin-4. Methods One hundred to 400 islets were transplanted to the abdominal muscle of nondiabetic mice. After 3 to 4 weeks, 0.2 to 0.5 MBq [177Lu]DO3A-VS-Cys40-Exendin-4 was administered intravenously. Sixty minutes postinjection abdominal organs and graft bearing muscle were retrieved, and the radioactive uptake measured in a well counter within 10 minutes. The specific uptake in native and transplanted islets was assessed by autoradiography. The total insulin-positive area of the islet grafts was determined by immunohistochemistry. Results Intramuscular islet grafts could easily be visualized by this tracer, and the background uptake was very low. There was a linear correlation between the radioactivity uptake and the number of transplanted islets, both for standardized uptake values and the total radiotracer uptake in each graft (percentage of injected dose). The quantified total insulin area of surviving β cells showed an even stronger correlation to both standardized uptake values (R = 0.96, P = 0.0002) and percentage of injected dose (R = 0.88, P = 0.0095). There was no correlation to estimated α cell mass. Conclusions [177Lu]DO3A-VS-Cys40-Exendin-4 could be used to quantify β-cell mass after experimental intramuscular islet transplantation. This technique may well be transferred to the clinical setting by exchanging Lutetium-177 radionuclide to a positron emitting Gallium-68. PMID:27819034

  12. New synthetic strategies towards psammaplin A, access to natural product analogues for biological evaluation.

    PubMed

    Baud, Matthias G J; Leiser, Thomas; Meyer-Almes, Franz-Josef; Fuchter, Matthew J

    2011-02-07

    New synthetic routes towards the natural product psammaplin A were developed with the particular view to preparing diverse analogues for biological assessment. These routes utilize cheap and commercially available starting materials, and allowed access to psammaplin A analogues not accessible via currently reported methods. Preliminary biological studies revealed these compounds to be the most potent non peptidic inhibitors of the enzyme histone deacetylase 1 (HDAC1, class I) discovered so far. Interestingly, psammaplin A and our synthetic analogues show class I selectivity in vitro, an important feature for the design and synthesis of future isoform selective inhibitors.

  13. A radiolabeled antiglobulin test for crossmatching platelet transfusions

    SciTech Connect

    Kickler, T.S.; Braine, H.G.; Ness, P.M.; Koester, A.; Bias, W.

    1983-02-01

    Despite the use of HLA-matched platelets for alloimmunized recipients, transfusion failures occur. In order to reduce these failures, researchers investigated the use of a radiolabeled antiglobulin technique for platelet crossmatching. The principle of the test is that of an indirect Coombs test using /sup 125/I labeled goat anti-human IgG. Incompatibility is determined by calculating a radioactivity antiglobulin test (RAGT) index. Using this technique, researchers performed 89 crossmatches on 19 leukemic or aplastic patients who were refractory to random donor platelets and receiving varying degrees of HLA-matched platelets. Effectiveness of the transfusion was assessed from the posttransfusion corrected platelet count increment (CCI) determined at 1 and 20 hr. When the RAGT index was 1.9 or less, the mean CCI at 1 lhr was 17,570 +/- 7003/cu mm, n . 55. When the RAGT index was 2.0 or greater, the mean CCI was 4237 +/- 4100/cu mm, n . 34. At 20 hr when the RAGT index was 1.9 or less, the mean CCI was 8722 +/- 3143/cu mm, n . 33, and when the index was 2.0 or greater, the mean CCI was 571 +/- 1286/cu mm, n . 23. Using this technique, one false negative resulted. Nine positive crossmatches with good increments at 1 hr were found; at 20 hr, however, the survival of these units was zero. These data suggest that this method is a useful adjunct in the selection of platelets in the refractory patient.

  14. Uptake of radiolabeled leukocytes in prosthetic graft infection

    SciTech Connect

    Serota, A.I.; Williams, R.A.; Rose, J.G.; Wilson, S.E.

    1981-07-01

    The utility of radionuclide labeled leukocytes in the demonstration of infection within vascular prostheses was examined. The infrarenal aorta was replaced with a 3 cm Dacron graft in 12 dogs. On the third postoperative day, six of the animals received an intravenous injection of 10(8) Staphylococcus aureus. Labeled leukocyte scans were performed at postoperative days one and three, and then weekly for 8 weeks with indium-111 and technetium-99 labeled autologous leukocytes. When scans showed focal uptake of isotope in the area of prosthetic material, the grafts were aseptically excised and cultured on mannitol-salt agar. Both control and infected animals had retroperitoneal isotope activity in the immediate postoperative period that disappeared by the end of the first week. By the eighth postoperative week, all of the animals that received the bacteremic challenge had both radionuclide concentration in the region of the vascular prosthesis and S. aureus cultured subsequently from the perigraft tissues. None of the control animals had either radionuclide or bacteriologic evidence of infection at the eighth postoperative week. The radiolabeled leukocyte scan is a highly sensitive and specific technique, clinically applicable for the diagnosis of vascular prosthetic infections.

  15. A radiolabeled antiglobulin test for crossmatching platelet transfusions.

    PubMed

    Kickler, T S; Braine, H G; Ness, P M; Koester, A; Bias, W

    1983-02-01

    Despite the use of HLA-matched platelets for alloimmunized recipients, transfusion failures occur. In order to reduce these failures, we investigated the use of a radiolabeled antiglobulin technique for platelet crossmatching. The principle of the test is that of an indirect Coombs test using 125I labeled goat anti-human IgG. Incompatibility is determined by calculating a radioactivity antiglobulin test (RAGT) index. Using this technique, we performed 89 crossmatches on 19 leukemic or aplastic patients who were refractory to random donor platelets and receiving varying degrees of HLA-matched platelets. Effectiveness of the transfusion was assessed from the posttransfusion corrected platelet count increment (CCI) determined at 1 and 20 hr. When the RAGT index was 1.9 or less, the mean CCI at 1 lhr was 17,570 +/- 7003/cu mm, n = 55. When the RAGT index was 2.0 or greater, the mean CCI was 4237 +/- 4100/cu mm, n = 34. At 20 hr when the RAGT index was 1.9 or less, the mean CCI was 8722 +/- 3143/cu mm, n = 33, and when the index was 2.0 or greater, the mean CCI was 571 +/- 1286/cu mm, n = 23. Using this technique, one false negative resulted. Nine positive crossmatches with good increments at 1 hr were found; at 20 hr, however, the survival of these units was zero. These data suggest that this method is a useful adjunct in the selection of platelets in the refractory patient.

  16. Mammary Analogue Secretory Carcinoma.

    PubMed

    Stevens, Todd M; Parekh, Vishwas

    2016-09-01

    Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumor that shares the same histologic appearance and ETV6 gene (12p13) rearrangement as secretory carcinoma of the breast. Prior to its recognition, MASC cases were commonly labeled acinic cell carcinoma and adenocarcinoma, not otherwise specified. Despite distinctive histologic features, MASC may be difficult to distinguish from other salivary gland tumors, in particular zymogen-poor acinic cell carcinoma and low-grade salivary duct carcinoma. Although characteristic morphologic and immunohistochemical features form the basis of a diagnosis of MASC, the presence of an ETV6-NTRK3 gene fusion is confirmatory. Given its recent recognition the true prognostic import of MASC is not yet clearly defined.

  17. Iodination and stability of somatostatin analogues: comparison of iodination techniques. A practical overview.

    PubMed

    de Blois, Erik; Chan, Ho Sze; Breeman, Wouter A P

    2012-01-01

    For iodination ((125/127)I) of tyrosine-containing peptides, chloramin-T, Pre-Coated Iodo-Gen(®) tubes and Iodo-Beads(®) (Pierce) are commonly used for in vitro radioligand investigations and there have been reliant vendors hereof for decades. However, commercial availability of these radio-iodinated peptides is decreasing. For continuation of our research in this field we investigated and optimized (radio-)iodination of somatostatin analogues. In literature, radioiodination using here described somatostatin analogues and iodination techniques are described separately. Here we present an overview, including High Performance Liquid Chromatography (HPLC) separation and characterisation by mass spectrometry, to obtain mono- and di-iodinated analogues. Reaction kinetics of (125/127)I iodinated somatostatin analogues were investigated as function of reaction time and concentration of reactants, including somatostatin analogues, iodine and oxidizing agent. To our knowledge, for the here described somatostatin analogues, no (127)I iodination and optimization are described. (Radio-)iodinated somatostatin analogues could be preserved with a >90% radiochemical purity for 1 month after reversed phase HPLC-purification.

  18. 77 FR 52368 - Manufacturer of Controlled Substances; Notice of Registration; American Radiolabeled Chemicals, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

    ... Radiolabeled Chemicals, Inc. By Notice dated May 9, 2012, and published in the Federal Register on May 21, 2012... Ibogaine (7260) I Lysergic acid diethylamide (7315) I Tetrahydrocannabinols (7370) I...

  19. Radiolabeled monoclonal antibodies for imaging and therapy: Potential, problems, and prospects: Scientific highlights

    SciTech Connect

    Srivastava, S.C.; Buraggi, G.L.

    1986-01-01

    This meeting focused on areas of research on radiolabeled monoclonal antibodies. Topics covered included the production, purification, and fragmentation of monoclonal antibodies and immunochemistry of hybridomas; the production and the chemistry of radionuclides; the radiohalogenation and radiometal labeling techniques; the in-vivo pharmacokinetics of radiolabeled antibodies; the considerations of immunoreactivity of radiolabeled preparations; the instrumentation and imaging techniques as applied to radioimmunodetection; the radiation dosimetry in diagnostic and therapeutic use of labeled antibodies; the radioimmunoscintigraphy and radioimmunotherapy studies; and perspectives and directions for future research. Tutorial as well as scientific lectures describing the latest research data on the above topics were presented. Three workshop panels were convened on ''Methods for Determining Immunoreactivity of Radiolabeled Monoclonal Antibodies - Problems and Pitfalls,'' Radiobiological and Dosimetric Considerations for Immunotherapy with Labeled Antibodies,'' and ''The Human Anti-Mouse Antibody Response in Patients.''

  20. INDUCED SPUTUM DERIVES FROM THE CENTRAL AIRWAYS: CONFIRMATION USING A RADIOLABELED AEROSOL BOLUS DELIVERY TECHNIQUE

    EPA Science Inventory

    Indirect evidence suggests that induced sputum derives from the surfaces of the bronchial airways. To confirm this experimentally, we employed a radiolabeled aerosol bolus delivery technique that preferentially deposits aerosol in the central airways in humans. We hypothesized th...

  1. New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies.

    PubMed

    Nallathamby, Prakash D; Mortensen, Ninell P; Palko, Heather A; Malfatti, Mike; Smith, Catherine; Sonnett, James; Doktycz, Mitchel J; Gu, Baohua; Roeder, Ryan K; Wang, Wei; Retterer, Scott T

    2015-04-21

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 ± 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90-110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with (14)C, with a final activity of 0.097 nCi mg(-1) of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and detection techniques. The radiolabeling approach

  2. New Surface Radiolabeling Schemes of Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) for Biodistribution Studies

    DOE PAGES

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; ...

    2015-01-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and 10 easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), wasmore » between 90 110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate 15 functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi/mg-1 of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-20 radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and 25 detection techniques. The radiolabeling

  3. New Surface Radiolabeling Schemes of Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) for Biodistribution Studies

    SciTech Connect

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, Jim; Doktycz, Mitchel John; Gu, Baohua; Roeder, Ryan; Wang, Wei; Retterer, Scott T.

    2015-01-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and 10 easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90 110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate 15 functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi/mg-1 of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-20 radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and 25 detection techniques. The

  4. An Efficient and Straightforward Method for Radiolabeling of Nanoparticles with {sup 64}Cu via Click Chemistry

    SciTech Connect

    Lee, Dong-Eun; Kim, Kwangmeyung; Park, Sang Hyun

    2015-07-01

    Recently, nanoparticles have received a great deal of interest in diagnosis and therapy applications. Since nanoparticles possess intrinsic features that are often required for a drug delivery system and diagnosis, they have potential to be used as platforms for integrating imaging and therapeutic functions, simultaneously. Intrinsic issues that are associated with theranostic nanoparticles, particularly in cancer treatment, include an efficient and straightforward radiolabeling method for understanding the in vivo biodistribution of nanoparticles to reach the tumor region, and monitoring therapeutic responses. Herein, we investigated a facile and highly efficient strategy to prepare radiolabeled nanoparticles with {sup 64}Cu via a strain-promoted azide, i.e., an alkyne cycloaddition strategy, which is often referred to as click chemistry. First, the azide (N3) group, which allows for the preparation of radiolabeled nanoparticles by copper-free click chemistry, was incorporated into glycol chitosan nanoparticles (CNPs). Second, the strained cyclooctyne derivative, dibenzyl cyclooctyne (DBCO) conjugated with a 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid (DOTA) chelator, was synthesized for preparing the pre-radiolabeled alkyne complex with {sup 64}Cu radionuclide. Following incubation with the {sup 64}Cu-radiolabeled DBCO complex (DBCO-PEG4-Lys-DOTA-{sup 64}Cu with high specific activity, 18.5 GBq/μ mol), the azide-functionalized CNPs were radiolabeled successfully with {sup 64}Cu, with a high radiolabeling efficiency and a high radiolabeling yield (>98%). Importantly, the radiolabeling of CNPs by copper-free click chemistry was accomplished within 30 min, with great efficiency in aqueous conditions. After {sup 64}Cu-CNPs were intravenously administered to tumor-bearing mice, the real time, in vivo biodistribution and tumor-targeting ability of {sup 64}Cu-CNPs were quantitatively evaluated by micro-PET images of tumor-bearing mice. These results

  5. New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies†

    PubMed Central

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, James; Doktycz, Mitchel J.; Gu, Baohua; Roeder, Ryan K.; Wang, Wei; Retterer, Scott T.

    2016-01-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 ± 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90–110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of –35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi mg–1 of NPs. In chronic studies, the biodistribution profile is tracked using low-level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and detection techniques. The radiolabeling approach

  6. Radiolabeled Exosomes for the Early Detection of Metastases and to Predict Breast Cancer Premetastatic Niche

    DTIC Science & Technology

    2014-08-01

    1 Award Number: W81XWH-13-1-0249 TITLE: Radiolabeled Exosomes for the Early Detection of...COVERED August 2013- July 2014 4. TITLE AND SUBTITLE Radiolabeled Exosomes for the Early Detection of Metastases 5a. CONTRACT NUMBER and to...disease in BC patients using cancer cell derived particles known as exosomes as a guide. We hypothesized that exosomes tagged with appropriate

  7. NASA/ESMD Analogue Mission Plans

    NASA Technical Reports Server (NTRS)

    Hoffman, Stephen J.

    2007-01-01

    A viewgraph presentation exploring Earth and its analogues is shown. The topics include: 1) ESMD Goals for the Use of Earth Analogues; 2) Stakeholders Summary; 3) Issues with Current Analogue Situation; 4) Current state of Analogues; 5) External Implementation Plan (Second Step); 6) Recent Progress in Utilizing Analogues; 7) Website Layout Example-Home Page; 8) Website Layout Example-Analogue Site; 9) Website Layout Example-Analogue Mission; 10) Objectives of ARDIG Analog Initiatives; 11) Future Plans; 12) Example: Cold-Trap Sample Return; 13) Example: Site Characterization Matrix; 14) Integrated Analogue Studies-Prerequisites for Human Exploration; and 15) Rating Scale Definitions.

  8. In vitro incorporation of radiolabeled cholesteryl esters into high and low density lipoproteins

    SciTech Connect

    Terpstra, A.H.; Nicolosi, R.J.; Herbert, P.N. )

    1989-11-01

    We have developed and validated a method for in vitro incorporation of radiolabeled cholesteryl esters into low density (LDL) and high density lipoproteins (HDL). Radiolabeled cholesteryl esters dissolved in absolute ethanol were mixed with LDL or HDL in the presence of lipoprotein-deficient serum (LPDS) as a source of core lipid transfer activity. The efficiency of incorporation was dependent on: (a) the core lipid transfer activity and quantity of LPDS, (b) the mass of added radiolabeled cholesteryl esters, (c) the length of incubation, and (d) the amount of acceptor lipoprotein cholesterol. The tracer incorporation was documented by repeat density gradient ultracentrifugation, agarose gel electrophoresis, and precipitation with heparin-MnCl2. The radiolabeling conditions did not affect the following properties of the lipoproteins: (1) chemical composition, (2) electrophoretic mobility on agarose gels, (3) hydrated density, (4) distribution of apoproteins on SDS gels, (5) plasma clearance rates, and (6) immunoprecipitability of HDL apoproteins A-I and A-II. Rat HDL containing radiolabeled cholesteryl esters incorporated in vitro had plasma disappearance rates identical to HDL radiolabeled in vivo.

  9. Synthesis and evaluation of an (125)I-labeled azide prosthetic group for efficient and bioorthogonal radiolabeling of cyclooctyne-group containing molecules using copper-free click reaction.

    PubMed

    Choi, Mi Hee; Shim, Ha Eun; Nam, You Ree; Kim, Hye Rim; Kang, Jung Ae; Lee, Dong-Eun; Park, Sang Hyun; Choi, Dae Seong; Jang, Beom-Su; Jeon, Jongho

    2016-02-01

    Herein we report the radiosynthesis of a pyridine derived azide prosthetic group for iodine radioisotope labeling of dibenzocyclooctyne (DBCO) conjugated molecules. The radiolabeling of the stannylated precursor 2 was conducted using [(125)I]NaI and chloramine-T to give (125)I-labeled azide ([(125)I]1) with high radiochemical yield (72±8%, n=4) and radiochemical purity (>99%). Using (125)I-labeled azide ([(125)I]1), cyclic RGD peptide and near infrared fluorescent molecule were efficiently labeled with modest to good radiochemical yields. The biodistribution study and SPECT/CT images showed that [(125)I]1 underwent rapid renal clearance. These results clearly demonstrated that [(125)I]1 could be used as an useful radiotracer for in vivo pre-targeted imaging as well as efficient in vitro radiolabeling of DBCO containing molecules.

  10. Apoptosis imaging studies in various animal models using radio-iodinated peptide.

    PubMed

    Kwak, Wonjung; Ha, Yeong Su; Soni, Nisarg; Lee, Woonghee; Park, Se-Il; Ahn, Heesu; An, Gwang Il; Kim, In-San; Lee, Byung-Heon; Yoo, Jeongsoo

    2015-01-01

    Apoptosis has a role in many medical disorders and treatments; hence, its non-invasive evaluation is one of the most riveting research topics. Currently annexin V is used as gold standard for imaging apoptosis. However, several drawbacks, including high background, slow body clearance, make it a suboptimum marker for apoptosis imaging. In this study, we radiolabeled the recently identified histone H1 targeting peptide (ApoPep-1) and evaluated its potential as a new apoptosis imaging agent in various animal models. ApoPep-1 (CQRPPR) was synthesized, and an extra tyrosine residue was added to its N-terminal end for radiolabeling. This peptide was radiolabeled with (124)I and (131)I and was tested for its serum stability. Surgery- and drug-induced apoptotic rat models were prepared for apoptosis evaluation, and PET imaging was performed. Doxorubicin was used for xenograft tumor treatment in mice, and the induced apoptosis was studied. Tumor metabolism and proliferation were assessed by [(18)F]FDG and [(18)F]FLT PET imaging and compared with ApoPep-1 after doxorubicin treatment. The peptide was radiolabeled at high purity, and it showed reasonably good stability in serum. Cell death was easily imaged by radiolabeled ApoPep-1 in an ischemia surgery model. And, liver apoptosis was more clearly identified by ApoPep-1 rather than [(124)I]annexin V in cycloheximide-treated models. Three doxorubicin doses inhibited tumor growth, which was evaluated by 30-40% decreases of [(18)F]FDG and [(18)F]FLT PET uptake in the tumor area. However, ApoPep-1 demonstrated more than 200% increase in tumor uptake after chemotherapy, while annexin V did not show any meaningful uptake in the tumor compared with the background. Biodistribution data were also in good agreement with the microPET imaging results. All of the experimental data clearly demonstrated high potential of the radiolabeled ApoPep-1 for in vivo apoptosis imaging.

  11. Heterobifunctional reagents: A new approach to radiolabeling of monoclonal antibodies

    SciTech Connect

    Wang, T.S.T.; Ng, A.K.; Fawwaz, R.A.; Liu, Z.; Alderson, P.O.

    1985-05-01

    The use of bifunctional chelate such as the cyclic anhydride of DTPA for radiolabeling antibodies (Abs) may lead to homopolymerization, and intra- or intermolecular cross-linking, with resulting denaturation and decrease immunoreactivity of Abs. The authors, therefore, investigated the use of heterobifunctional reagents, whereby one group selectively couples to the amino group of the Ab and the other group to the radiometal for Ab labeling. One such reagent, 2,6-Dioxo-N-(carboxymethyl)morphine (DCM) was synthesized by reacting nitrilotriacetic acid with acetic anhydride. The other agent tested was commercially available N-Succinimidyl-3-(2-pyridyldithio) propionate (SPDP). These agents were evaluated independently for their ability to label a monoclonal antibody (MoAb) to a melanoma associated antigen (Ag). Labeling proceeded at a 2mg/ml concentration of the Ab, at HEPES pH 8.2, and 7.0, respectively, at room temperature for 30 min. The conjugate subsequently was labeled with Tc-99m or In-111. For comparison, the same labeled Abs also were prepared by using the cyclic anhydride of DTPA. Binding of the Ab to melanoma cells and control cells then was assayed. The results of cell binding experiments (N=3 per agent) in the region of Ag excess (X+-SD) were as follows: 62.6 +- 2.83% for Tc-99m-DCM-MoAb and 41.3+-1.84% for Tc-99m-SPDP-MoAb vs. 28.6 +- 1.16% for Tc-99m-DTPA-MoAb (p<0.01); 56.2 +- 2.97% for In-111-DCM-MoAb vs. 28.6 +- 1.16% for In-111-DTPA-M0Ab. Binding of all agents to the control lymphoid cell line was less than 3%. These results suggest that heterobifunctional reagents can reduce the loss of immunoreactivity of labeled MoAbs.

  12. Synthesis of tyrocidine A and its analogues by spontaneous cyclization in aqueous solution.

    PubMed

    Bu, Xianzhang; Wu, Xiaoming; Xie, Guiyang; Guo, Zhihong

    2002-08-22

    [reaction: see text] Head-to-tail cyclization of peptides is a multistep process involving tedious C-terminal activation and side chain protection. Here we report a facile, quantitative cyclization method in aqueous ammonia solution for the total syntheses of the cyclic decapeptide antibiotic Tyrocidine A and its analogues from their fully deprotected linear thioester precursors on a solid support. This novel aqueous method is conformation-dependent and may be applicable to syntheses of other natural cyclic peptides.

  13. Utilizing the Multiradionuclide Resolving Power of SPECT and Dual Radiolabeled Single Molecules to Assess Treatment Response of Tumors

    PubMed Central

    Xu, Baogang; Shokeen, Monica; Sudlow, Gail P.; Harpstrite, Scott E.; Liang, Kexian; Cheney, Philip P.; Edwards, W. Barry; Sharma, Vijay; Laforest, Richard; Akers, Walter J.; Achilefu, Samuel

    2016-01-01

    Purpose Single photon emission computed tomography (SPECT) radionuclide pairs having distinct decay rates and different energy maxima enable simultaneous detection of dual gamma signals and real-time assessment of dynamic functional and molecular processes in vivo. Here, we report image acquisition and quantification protocols for a single molecule labeled with two different radionuclides for functional SPECT imaging. Procedures LS370 and LS734 were prepared using modular solid phase peptide synthesis. Each agent has a caspase-3 cleavable reporting motif, flanked by a tyrosine residue and a chelator at the opposite end of molecule. Cell uptake and efflux were assessed in human MDA-MB-231 breast cancer cells. Biodistribution studies were conducted in tumor naive and orthotopic 4T1 metastatic breast cancer tumor mice. NanoSPECT dual-imaging validation and attenuation correction parameters were developed using phantom vials containing varying radionuclide concentrations. Proof-of-principle SPECT imaging was performed in MMTV-PyMT transgenic mice. Results LS370 and LS734 were singly or dually radiolabeled with 125I and 111In or 99mTc. Cell assays demonstrated 11-fold higher percent uptake (P<0.001) of [125I]LS734 (3.6±0.5) compared to [125I]LS370 (0.3±0.3) at 2 h. Following chemotherapy, cellular retention of [125I]LS734 was 3-fold higher (P<0.05) than untreated cells. Pharmacokinetics at 1 h postinjection demonstrated longer blood retention (%ID/g) for [125I]LS734 (3.2±0.9) compared to [125I]LS370 (1.6±0.1). In mice bearing bilateral orthotopic 4T1 tumors, the uptake (%ID/g) was 2.4±0.3 for [125I]LS734 and 1.2±0.03 for [125I]LS370. The iodinated tyrosine peptide residue label was stable under in vitro conditions for up to 24 h; rapid systemic deiodination (high thyroid uptake) was observed in vivo. Phantom studies using standards demonstrated deconvolution of radionuclide signals based on different gamma ray energies. In MMTV-PyMT mice imaged with dual

  14. New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies

    NASA Astrophysics Data System (ADS)

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, James; Doktycz, Mitchel J.; Gu, Baohua; Roeder, Ryan K.; Wang, Wei; Retterer, Scott T.

    2015-04-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 +/- 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90-110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi mg-1 of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and detection techniques. The radiolabeling approach described

  15. Efficient one-step radiolabeling of monoclonal antibodies to high specific activity with Actinium-225 for alpha-particle radioimmunotherapy of cancer

    PubMed Central

    Maguire, William F.; McDevitt, Michael R.; Smith-Jones, Peter M.; Scheinberg, David A.

    2015-01-01

    Targeted alpha-particle radiation using the radioisotope 225Actinium (225Ac) is a promising form of therapy for various types of cancer. Historical obstacles to the use of 225Ac have been the difficulty in finding suitable chelators to stably attach it to targeting vehicles such as peptides and monoclonal antibodies, the low specific activities of the products, and the lack of cost-effective radiolabeling procedures. We initially solved the first problem with a procedure involving two chemical steps that has been used as a standard in preclinical and clinical studies. However, this procedure involves the loss of 90% of the input 225Ac. A more efficient, economical process is needed to facilitate the more widespread use of 225Ac. Methods We conjugated representative antibodies with two forms of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), as well as other chelators as controls. We developed conditions to radiolabel these constructs in one chemical step and characterized their stability, immunoreactivity, biodistribution, and therapeutic efficacy in healthy and tumor-bearing mice. Results DOTA- antibody constructs were labeled to a wide range of specific activities in one chemical step at 37 °C. Radiochemical yields were approximately 10-fold higher and specific activities were up to 30-fold higher than with the previous approach. The products retained immunoreactivity and were stable to serum challenge in vitro and in mice. Labeling kinetics of DOTA- antibody constructs linked through a benzyl isothiocyanate linkage were more favorable than those linked through a N-hydroxysuccinimide linkage. Tissue distribution was similar but not identical between the constructs. The constructs produced specific therapeutic responses in a mouse model of acute myeloid leukemia. Conclusion We have characterized an efficient, one-step radiolabeling method that produces stable, therapeutically active conjugates of antibodies with 225Ac at high specific activity

  16. Peptide bioregulation of aging: results and prospects.

    PubMed

    Anisimov, Vladimir N; Khavinson, Vladimir Kh

    2010-04-01

    The review comprises the results of author's long-term investigation in the mechanisms of aging and a role of peptide bioregulators in prevention of age-related pathology. A number of small peptides have been isolated from different organs and tissues and their analogues (di-, tri-, tetrapeptides) were synthesized from the amino acids. It was shown that long-term treatment with some peptide preparations increased mean life span by 20-40%, slow down the age-related changes in the biomarkers of aging and suppressed development of spontaneous and induced by chemical or radiation carcinogens tumorigenesis in rodents. Possible mechanisms of the biological effects of small peptides are discussed in the paper. The results of clinical applications of peptide preparation during the period of 6-12 years are presented as well.

  17. Targeting and therapy of human glioma xenografts in vivo utilizing radiolabeled antibodies

    SciTech Connect

    Williams, J.A.; Wessels, B.W.; Edwards, J.A.; Kopher, K.A.; Wanek, P.M.; Wharam, M.D.; Order, S.E.; Klein, J.L. )

    1990-02-01

    Radiolabeled antibodies provide a potential basis for selective radiotherapy of human gliomas. We have measured tumor targeting by radiolabeled monoclonal antibodies directed against neuroectodermal and tumor-associated antigens in nude mice bearing human glioma xenografts. Monoclonal P96.5, a mouse IgG2a immunoglobulin, defines an epitope of a human melanoma cell surface protein and specifically binds the U-251 human glioma as measured by immunoperoxidase histochemistry. IIIIn-radiolabeled P96.5 specifically targets the U-251 human glioma xenograft and yields 87.0 microCi of tumor activity/g/100 microCi injected activity compared to 4.5 microCi following administration of 100 microCi radiolabeled irrelevant monoclonal antibody. Calculations of targeting ratios demonstrate the deposited dose to be 11.6 times greater with radiolabeled P96.5 administration compared to irrelevant monoclonal antibody. The dose found in normal organs is less than 20% of that in the tumor, further supporting specific targeting of the human glioma xenograft by this antibody. Monoclonal antibody ZME018, which defines a second melanoma-associated antigen, demonstrates positive immunoperoxidase staining of the tumor, but comparatively decreased targeting. To test the therapeutic potential of 90Y-radiolabeled P96.5 and ZME018, tumors and normal sites were implanted with miniature thermoluminescent dosimeters. Average absorbed doses of 3770 +/- 445 (SEM) and 645 +/- 48 cGy in tumor, 353 +/- 41 and 222 +/- 13 cGy in a contralateral control i.m. site, 980 +/- 127 and 651 +/- 63 cGy in liver, and 275 +/- 14 and 256 +/- 18 cGy in total body were observed 7 days following administration of 100 microCi 90Y-radiolabeled P96.5 and ZME018, respectively. Calculations of absorbed dose by the medical internal radiation dose method confirmed thermoluminescent dosimeter absorbed dose measurements.

  18. A novel, cysteine-modified chelation strategy for the incorporation of [MI(CO)3]+ (M = Re, 99mTc) in an α-MSH peptide

    PubMed Central

    Jiang, Han; Kasten, Benjamin B.; Liu, Hongguang; Qi, Shibo; Liu, Yang; Tian, Mei; Barnes, Charles L.; Zhang, Hong; Cheng, Zhen; Benny, Paul D.

    2012-01-01

    Engineering peptide-based targeting agents with residues for site specific and stable complexation of radionuclides is a highly desirable strategy for producing diagnostic and therapeutic agents for cancer and other diseases. In this report, a model N-S-NPy ligand (3) and a cysteine-derived alpha-melanocyte stimulating hormone (α-MSH) peptide (6) were used as novel demonstrations of a widely applicable chelation strategy for incorporation of the [MI(CO)3]+ (M = Re, 99mTc) core into peptide-based molecules for radiopharmaceutical applications. The structural details of the core ligand-metal complexes as model systems were demonstrated by full chemical characterization of fac-[ReI(CO)3(N,S,NPy-3)]+ (4) and comparative high performance liquid chromatography (HPLC) analysis between 4 and [99mTcI(CO)3(N,S,NPy-3)]+ (4a). The α-MSH analogue bearing the N-S-NPy chelate on a modified cysteine residue (6) was generated and complexed with [MI(CO)3]+ to confirm the chelation strategy’s utility when applied in a peptide-based targeting agent. Characterization of the ReI(CO)3-6 peptide conjugate (7) confirmed the efficient incorporation of the metal center, and the 99mTcI(CO)3-6 analogue (7a) was explored as a potential single photon emission computed tomography (SPECT) compound for imaging the melanocortin 1 receptor (MC1R) in melanoma. Peptide 7a showed excellent radiolabeling yields and in vitro stability during amino acid challenge and serum stability assays. In vitro B16F10 melanoma cell uptake of 7a reached a modest value of 2.3 ± 0.08% of applied activity at 2 h at 37 °C while this uptake was significantly reduced by coincubation with a nonlabeled α-MSH analogue, NAPamide (3.2 µM) (P < 0.05). In vivo SPECT/X-ray computer tomography (SPECT/CT) imaging and biodistribution of 7a were evaluated in a B16F10 melanoma xenografted mouse model. SPECT/CT imaging clearly visualized the tumor at 1 h post injection (p.i.) with high tumor-to-background contrast. Blocking

  19. 99mTc-Labeled-rhTSH Analogue (TR1401) for Imaging Poorly Differentiated Metastatic Thyroid Cancer

    PubMed Central

    Galli, Filippo; Manni, Isabella; Piaggio, Giulia; Balogh, Lajos; Weintraub, Bruce D.; Szkudlinski, Mariusz W.; Fremont, Valerie; Dierckx, Rudi A.J.O.

    2014-01-01

    Background: Differentiated thyroid carcinomas originating from thyroid follicular cells are frequent tumors of the thyroid with relatively good prognosis due to improved surgical techniques and follow-up procedures. Poorly differentiated thyroid cancers, which lose iodine uptake ability, in most cases still express thyrotropin (TSH) receptors (TSHR). Therefore, the aim of this study was to radiolabel a superagonist recombinant human TSH (rhTSH) analogue for imaging poorly differentiated thyroid cancer. Methods: The TSHR superagonist, TR1401, was labeled with 99mTc using an indirect method via succinimidyl-6-hydrazinonicotinate hydrochloride conjugation. In vitro quality controls included SDS-PAGE, cysteine challenge, and cell-binding assay on TSHR positive cell lines (JP09 and ML-1). In vivo studies included tumor targeting experiments in athymic nude CD-1 mice xenografted with several different TSHR positive cells (JP09, K1, and ML-1) and TSHR negative cells (JP02) as control. Results: The superagonist rhTSH analogue TR1401 was labeled with high labeling efficiency (>95%) and high specific activity (9250 MBq/mg). The labeled molecule retained its biologic activity and structural integrity. In tumor targeting experiments, a focal uptake of radiolabeled TR1401 was observed in TSHR positive cells but not in TSHR negative cells. The same observation was made in a dog with spontaneous intraglandular thyroid cancer. Conclusions: We were able to radiolabel the rhTSH superagonist analogue TR1401 with 99mTc efficiently with retention of in vitro and in vivo binding capacity to TSHR. The relative role of such novel radiopharmaceutical versus 131I scanning of thyroid cancer will require future histopathologic and clinical studies, but it may open new perspectives for presurgical staging of thyroid cancer, and diagnosis of radioiodine negative local relapses and/or distant metastases. PMID:24801227

  20. Radiolabeled technetium chelates for use in renal function determinations

    DOEpatents

    Fritzberg, Alan; Kasina, Sudhaker; Johnson, Dennis L.

    1994-01-01

    The present invention is directed to novel radiopharmaceutical imaging agents incorporating Tc-99m as a radiolabel. In particular, the novel imaging agents disclosed herein have relatively high renal extraction efficiencies, and hence are useful for conducting renal function imaging procedures. The novel Tc-99m compounds of a present invention have the following general formula: ##STR1## wherein X is S or N; and wherein Y is --H or wherein Y is ##STR2## and where R.sub.1 is --H, --CH.sub.3, or --CH.sub.2 CH.sub.3 ; R.sub.2 is --H, --CH.sub.2 CO.sub.2 H, --CH.sub.2 CONH.sub.2, --CH.sub.2 CH.sub.2 CO.sub.2 H, --CH.sub.2 CH.sub.2 CONH.sub.2, --CH.sub.3, --CH.sub.2 CH.sub.3, CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 OH; and Z is --H, --CO.sub.2 H, --CONH.sub.2, --SO.sub.3 H, --SO.sub.2 NH.sub.2, or --CONHCH.sub.2 CO.sub.2 H; and the Tc is Tc-99m; and water-soluble salts thereof. Of the foregoing, the presently preferred Tc-99m compound of the present invention is Tc-99m-mercaptoacetylglycylglycylglycine (Tc-99m-MAGGG). The present invention is also directed to novel chelating agents that may be reacted with Tc-99m to form the foregoing compounds. Such novel chelating agents have the following general formula. ##STR3## where X and Y have the same definitions as above, and wherein Y' is --H.sub.2 when X is N, or wherein Y' is --H, or a suitable protective group such as --COCH.sub.3, --COC.sub.6 H.sub.5, --CH.sub.2 NHCOCH.sub.3, --COCF.sub.3, or --COCH.sub.2 OH when X is S. The present invention also provides methods for preparing and using the novel Tc-99m compounds.

  1. Radiolabeled technetium chelates for use in renal function determinations

    DOEpatents

    Fritzberg, Alan; Kasina, Sudhakar; Johnson, Dennis L.

    1990-01-01

    The present invention is directed to novel radiopharmaceutical imaging agents incorporating Tc-99m as a radiolabel. In particular, the novel imaging agents disclosed herein have relatively high renal extraction efficiencies, and hence are useful for conducting renal function imaging procedures. The novel Tc-99m compounds of a present invention have the following general formula: ##STR1## wherein X is S or N; and wherein Y is--H or wherein Y is ##STR2## and where R.sub.1 is --H, --CH.sub.3, or --CH.sub.2 CH.sub.3 ; R.sub.2 is --H, --CH.sub.2 CO.sub.2 H, --CH.sub.2 CONH.sub.2, --CH.sub.2 CH.sub.2 CO.sub.2 H, --CH.sub.2 CH.sub.2 CONH.sub.2, --CH.sub.3, --CH.sub.2 CH.sub.3, CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 OH; and Z is --H, --CO.sub.2 H, --CONH.sub.2, --SO.sub.3 H, --SO.sub.2 NH.sub.2, or --CONHCH.sub.2 CO.sub.2 H; and the Tc is Tc-99m; and water-soluble salts thereof. Of the foregoing, the presently preferred Tc-99m compound of the present invention is Tc-99m-mercaptoacetylglycylglycylglycine (Tc-99m-MAGGG). The present invention is also directed to novel chelating agents that may be reacted with Tc-99m to form the foregoing compounds. Such novel chelating agents have the following general formula. ##STR3## where X and Y have the same definitions as above, and wherein Y' is --H.sub.2 when X is N, or wherein Y' is --H, or a suitable protective group such as --COCH.sub.3, --COC.sub.6 H.sub.5, --CH.sub.2 NHCOCH.sub.3, --COCF.sub.3, or --COCH.sub.2 OH when X is S. The present invention also provides methods for preparing and using the novel Tc-99m compounds.

  2. Microbial contamination detection at low levels by [125]I radiolabeling

    NASA Astrophysics Data System (ADS)

    Summers, David; Karouia, Fathi

    Contamination of mission spacecraft is an ongoing issue. A broad diversity of microorganisms have been detected in clean rooms where spacecraft are assembled. Some of which, depicted as oligotroph, are of special regard, as they are capable of colonizing inorganic surfaces like metal, and have been shown to be a concern for forward contamination of pristine celestial bodies. Currently, the NASA standard assay is the only approved assay intended for the enumeration of spores and heterotrophic microbial populations. However, culture-based microbial detection methods underestimate the viable microbial population. More recently, adenosine triphosphate (ATP) bioluminescence and limulus amebocyte lysate (LAL) assays, which employ measure-ments of selected metabolic products as a proxy of biomass, have been used successfully to circumvent the necessity of the growth of microorganisms in order to estimate the biodurdens associated with spacecraft assembly facility. However, these methods have limitation in the amount of cells that can be detected, i.e., 103 cells, and the type of microorganisms respec-tively. This work seeks to develop a new highly sensitive method for the determination of bioburdens (and the detection of microorganisms and life) that is independant of the type of organism while preserving a good turn-around time for analysis for planetary protection purposes. The assay is based on the detection of the organism's protein by labeling them by radioiodination, 125 I, of aromatic rings on tyrosine amino acids residues. Radiolabeling techniques are inherently sensitive and 125 I, in particular, benefits from a 60 day half-life, providing greater activity and signal per unit number of labels. Furthermore, microorganisms can contain over 50% of protein by dry weight. Thus, just one label per protein increases the sensitivity, compared to the ATP and LAL assays, by one and three orders of magnitude by using standard detection methods and the use of multiphoton

  3. Preparation and Evaluation of Radiolabeled Antibody Recruiting Small Molecules That Target Prostate-Specific Membrane Antigen for Combined Radiotherapy and Immunotherapy.

    PubMed

    Genady, Afaf R; Janzen, Nancy; Banevicius, Laura; El-Gamal, Mahmoud; El-Zaria, Mohamed E; Valliant, John F

    2016-03-24

    The feasibility of developing a single agent that can deliver radioactive iodine and also direct cellular immune function by engaging endogenous antibodies as an antibody-recruiting small molecule (ARM) was determined. A library of new prostate-specific membrane antigen (PSMA)-binding ligands that contained antibody-recruiting 2,4-dinitrophenyl (DNP) groups and iodine were synthesized and screened in vitro and in vivo. A lead compound (9b) showed high affinity for PSMA and the ability to bind anti-DNP antibodies. Biodistribution studies of the iodine-125 analogue showed 3% ID/g in LNCaP xenograft tumors at 1 h postinjection with tumor-to-blood and tumor-to-muscle ratios of 10:1 and 44:1, respectively. The radiolabeled analogue was bound and internalized by LNCaP cells, with both functions blocked using a known PSMA inhibitor. A second candidate showed high tumor uptake (>10% ID/g) but had minimal binding to anti-DNP antibodies. The compounds reported represent the first examples of small molecules developed specifically for combination immunotherapy and radiotherapy for prostate cancer.

  4. Plasma half-life and organ uptake ratio of radiolabeled glandular kallikrein in control and nephrectomized rats

    SciTech Connect

    Nishimura, K.; Iwata, T.; Kokubu, T.

    1986-01-01

    The purified rat urinary kallikrein was radiolabeled by lactoperoxidase method and by chloramine T method. Plasma half-life of radiolabeled kallikrein was 5.06 +/- 0.59 (n = 5) min in control rats and 5.24 +/- 0.42 (n = 5) min in nephrectomized rats. There was no difference between two groups. From autoradiogram, main metabolic organs of radiolabeled kallikrein were liver, kidney and spleen. Total uptake of radiolabeled kallikrein in ech organ was the highest in liver (73.2%). The uptake per g tissue of radiolabeled kallikrein in each organ was high in liver (33.0%), kidney (31.4%) and spleen (21.1%). These results suggest that the active kallikrein is metabolized mainly in the liver, and kidney is not so an important organ to metabolize or to eliminate the active kallikrein in plasma. In order to clarify the mode of existence of active kallikrein in plasma, the following experiment was done by using disc gel electrophoresis. Radioactive profile of radiolabeled kallikrein showed one peak (Rf = 1.0), but radiolabeled kallikrein mixed with rat plasma showed two peaks, that is small peak (Rf = 1.0), and main peak (RF = 0.5). The most of radiolabeled kallikrein was bound to plasma protein and only five per cent was in free form. Furthermore, the binding of radiolabeled kallikrein to plasma protein was interfered by the addition of active kallikrein. These results suggest the possibility of existence of kallikrein binding protein in plasma.

  5. Radiolabel ratio method for measuring pulmonary clearance of intratracheal bacterial challenges

    SciTech Connect

    LaForce, F.M.; Boose, D.S.

    1988-02-01

    Calculation of bacterial clearance is a fundamental step in any study of in situ lung antibacterial defenses. A method is described whereby about 85% of a radiolabeled bacterial inoculum was consistently introduced into the bronchopulmonary tree of a mouse by the intratracheal route. Mice were then killed 1 and 4 hours later; their lungs were removed aseptically and homogenized, and viable bacteria and radiolabel counts were determined. Radiolabel counts fell slowly, and more than 80% of the original radiolabel was still present in homogenized lung samples from animals sacrificed 4 hours after challenge. Bacteria/isotope ratios for the bacterial inoculum and homogenized lung samples from animals sacrificed immediately after challenge were very similar. Bacterial clearance values were the same whether computed from bacterial counts alone or according to a radiolabel ratio method whereby the change in the bacteria/isotope ratio in ground lung aliquots was divided by a similar ratio from bacteria used to inoculate animals. Some contamination resulted from oral streptococci being swept into the bronchopulmonary free during the aspiration process. This contamination was not a problem when penicillin was incorporated into the agar and penicillin-resistant strains were used for the bacterial challenges.

  6. Antigen-binding site protection during radiolabeling leads to a higher immunoreactive fraction

    SciTech Connect

    Van den Abbeele, A.D.; Aaronson, R.A.; Daher, S.; Taube, R.A.; Adelstein, S.J.; Kassis, A.I. )

    1991-01-01

    It is generally accepted that the immunointegrity of an antibody (Ab) depends on the preservation of its antigen-binding sites. Our goal was to radiolabel an antibody at several iodine:antibody molar ratios under conditions protecting its combining site and to compare its immunoreactive fraction (IRF) and electrophoretic mobility with those of the same antibody radiolabeled without protection. The data indicate that an antibody radiolabeled while its antigen-binding site is occupied by its antigen had the same IRF, regardless of the number of iodine atoms per antibody molecule. On the other hand, even at an I:Ab ratio of 1:1, the IRF of the same antibody radiolabeled without protection was lower than that of a protected one and decreased with increasing I:Ab ratios. In addition, the iodination of these Ab changes their electrophoretic mobility; however, when the Ab is labeled in the protected state, the degree of change is less. The binding of an antibody to its antigen prior to radiolabeling, therefore, enhances its immuno-integrity and prevents major conformational changes as reflected by electrophoresis.

  7. Combinatorial discovery of tumor targeting peptides using phage display.

    PubMed

    Landon, Linda A; Deutscher, Susan L

    2003-10-15

    Peptides possess appropriate pharmacokinetic properties to serve as cancer imaging or therapeutic targeting agents. Currently, only a small number of rationally-derived, labeled peptide analogues that target only a limited subset of antigens are available. Thus, finding new cancer targeting peptides is a central goal in the field of molecular targeting. Novel tumor-avid peptides can be efficiently identified via affinity selections using complex random peptide libraries containing millions of peptides that are displayed on bacteriophage. In vitro and in situ affinity selections may be used to identify peptides with high affinity for the target antigen in vitro. Unfortunately, it has been found that peptides selected in vitro or in situ may not effectively target tumors in vivo due to poor peptide stability and other problems. To improve in vivo targeting, methodological combinatorial chemistry innovations allow selections to be conducted in the environment of the whole animal. Thus, new targeting peptides with optimal in vivo properties can be selected in vivo in tumor-bearing animals. In vivo selections have been proven successful in identifying peptides that target the vasculature of specific organs. In addition, in vivo selections have identified peptides that bind specifically to the surface of or are internalized into tumor cells. In the future, direct selection of peptides for cancer imaging may be expedited using genetically engineered bacteriophage libraries that encode peptides with intrinsic radiometal-chelation or fluorescent sequences.

  8. Highly potent metallopeptide analogues of luteinizing hormone-releasing hormone

    SciTech Connect

    Bajusz, S.; Janaky, T.; Csernus, V.J.; Bokser, L.; Fekete, M.; Srkalovic, G.; Redding, T.W.; Schally, A.V. )

    1989-08-01

    Metal complexes related to the cytotoxic complexes cisplatin (cis-diamminedichloroplatinum(II)) and transbis(salicylaldoximato)copper(II) were incorporated into suitably modified luteinizing hormone-releasing hormone (LH-RH) analogues containing D-lysine at position 6. Some of the metallopeptides thus obtained proved to be highly active LH-RH agonists or antagonists. Most metallopeptide analogues of LH-RH showed high affinities for the membrane receptors of rat pituitary and human breast cancer cells. Some of these metallopeptides had cytotoxic activity against human breast cancer and prostate cancer and prostate cancer cell lines in vitro. Such cytostatic metallopeptides could be envisioned as targeted chemotherapeutic agents in cancers that contain receptors for LH-RH-like peptides.

  9. WE-G-303-04: Intrinsically Radiolabeled Nanoparticles: An Emerging Paradigm

    SciTech Connect

    Cai, W.

    2015-06-15

    Over the last decade, there has been a growing interest in applying nanotechnology to cancer detection, treatment, and treatment monitoring. Advances in nanotechnology have enabled the fabrication of nanoparticles from various materials with different shapes and sizes. Nanoparticles can be accumulated preferentially within tumors by either “passive targeting” through a phenomenon typically known as “enhanced permeability and retention” or “active targeting” in which nanoparticles are conjugated with antibodies or peptides directed against tumor and/or stromal markers. The tumor specificity of nanoparticles in conjunction with their unique physicochemical properties offers many novel strategies for cancer treatment and detection. For example, notable approaches in the radiation oncology setting include the use of gold nanoparticles for radiation response modulation of tumor or normal tissue and thermal ablation or hyperthermia treatment of tumors. Some of these approaches are currently being tested either on humans or on animals and, very likely, will become the clinical reality in the near future. Various computational and experimental techniques have also been applied to address unique research issues associated with nanoparticles and may become the standard tools for future investigations and clinical translations. Therefore, both clinicians and researchers may need to be properly educated about the basic principles as well as the promise of nanoparticle-based applications with regard to the future of cancer diagnostics and therapeutics. This symposium will familiarize the audience with the potential applications of nanoparticles in oncologic imaging and therapy using specific illustrative examples. The audience will be properly oriented by these illustrative examples to the multiple avenues for collaborative research amongst interdisciplinary teams of physicists, clinicians, engineers, chemists, and biologists in industry and academia. Learning

  10. Potent cyclic enkephalin analogues for delta opioid receptors in the rat brain

    SciTech Connect

    Lui, G.; Kao, J.; Hruby, V.; Morelli, M.; Gulya, K.; Yamamura, H.I.

    1986-03-01

    (/sup 3/H) (D-Pen/sup 2/,D-Pen/sup 5/) enkephalin ((/sup 3/H)DPDPE) and (/sup 3/H) (D-Pen/sup 2/, L-Pen/sup 5/) enkephalin ((/sup 3/H)DPLPE) characterization studies showed high affinity binding of these radioligands to rat brain membranes with dissociation constants of 1.8 and 1.0 nM, respectively, while a similar number of receptor density was found with both radiolabeled ligands (77 fmoles/mg protein). Unlabeled DPDPE inhibited both radioligands with high affinity (IC50 = 7 nM0 while morphine (IC50 = 80 nM), DAGO (IC50 = 250 nM) and PLO17 (no inhibition at 1000 nM) were less effective in inhibiting the binding, thus, illustrating the selective action of these radiolabeled ligands at the delta opioid receptor. A series of conformationally restricted D-penicillamine containing cyclic enkephalin analogues were synthesized using standard solid phase methods and their ability to inhibit (/sup 3/H)DPDPE and (/sup 3/H)DPLPE were examined in rat brain radioreceptor assays. Substitutions in the DPDPE molecule were made in phe/sup 4/. These substitutions were pNO/sub 2/-phe/sup 4/, beta-methyl-phe/sup 4/, pNO/sub 2/-beta-methyl-phe/sub 4/, pNO/sub 2/-beta-methyl-phe/sup 4/ (three isomeric forms: A,B,D). The IC50 values for the above enkephalin analogues were 3.7, 16, 7, 7, 200 nM, respectively. Thus, these potent analogues of DPDPE should be useful in determining the structure activity relationships of the delta opioid receptor in rat brain.

  11. Peptide Transport through the Blood-Brain Barrier

    DTIC Science & Technology

    1989-01-01

    analogues for treatment of membiry,.ACIH analogues for treatmen of post-traumatic epilepsy), should these peptides be capable of traversing the BBB...thus far. In addition, since cationization does not destroy immunoglobulin G antigenicity, the use of cationized immunoglobulins may be used for... aerosolized insulin. Mixed-meal studies and long-term use in Type I diabetes. N. Engl. J. Med. 312:1078-1084. 12. Pardridge, W.M. (1988): Recent advances in

  12. Antimicrobial Peptides Under Clinical Trials.

    PubMed

    Greber, Katarzyna E; Dawgul, Małgorzata

    2017-01-01

    Today microbial drug resistance has become a serious problem not only within inpatient setting but also within outpatient setting. Repeated intake and unnecessary usage of antibiotics as well as the transfer of resistance genes are the most important factors that make the microorganisms resistant to conventional antibiotics. A large number of antimicrobials successfully used for prophylaxis and therapeutic purposes have now become ineffective [1, 2]. Therefore, new molecules are being studied to be used in the treatment of various diseases. Some of these molecules are structural compounds based on a combination of peptides, for example, naturally occurring endogenous peptide antibiotics and their synthetic analogues or molecules designed de novo using QSAR (quantitative structureproperty relationships)-based methods [3]. Trying to exploit numerous advantages of antimicrobial peptides such as high potency and selectivity, broad range of targets, potentially low toxicity and low accumulation in tissues, pharmaceutical industry aims to develop them as commercially available drugs and appropriate clinical trials are being conducted [4]. In this paper we define clinical trials steps and describe current status of several antimicrobial peptides under clinical development as well as briefly depict peptide drug formulation.

  13. Macrophage uptake and retention of radiolabeled glycopeptidolipid antigens associated with the superficial L1 layer of Mycobacterium intracellulare serovar 20.

    PubMed Central

    Hooper, L C; Johnson, M M; Khera, V R; Barrow, W W

    1986-01-01

    Glycopeptidolipid (GPL) antigens which are associated with the superficial L1 layer of Mycobacterium intracellulare serovar 20 were labeled with radioisotopes by means of internal labeling techniques and used in macrophage uptake and retention studies. The use of tritiated alanine and phenylalanine allowed the incorporation of label into the GPL invariant fatty acyl peptide core, which is common to all members of the Mycobacterium avium-M. intracellulare complex. Radiolabeled GPL antigens were then purified by a one-step column chromatographic procedure and subsequently used to determine the maximum uptake and retention in peritoneal macrophages isolated from C57BL/6 and CBA/J mice. Maximum uptake for peritoneal macrophages from both strains of mice occurred at a concentration between 200 and 250 micrograms of antigen per ml of medium when 3.4 X 10(5) cells were pulsed. Timed experiments demonstrated that approximately 20% of the antigens remained associated with the macrophages up to 4 days after a pulse of 200 micrograms of GPL, and examination of chloroform-extractable components from both macrophages and spent medium revealed that 98% or more of the radioactivity corresponded to intact GPL components. The ability of the GPL antigens to become associated with macrophages is demonstrated by these results, which strongly suggest that these potentially important mycobacterial antigens are inert to degradation by those cells. Images PMID:3531012

  14. Therapeutic uses of gastrointestinal peptides.

    PubMed

    Redfern, J S; O'Dorisio, T M

    1993-12-01

    The GI tract is one of nature's great pharmacies. Most, if not all, biologically active peptides can be found there, and it is quite likely that others remain to be discovered. Our ability to exploit this resource has expanded considerably over the past two decades. Advances in analytical techniques have allowed investigators to rapidly isolate and purify new compounds from tissue extracts. Sequencing and de novo synthesis of newly discovered peptides are now routine, and the structural modifications required to alter activity and tailor a compound to a particular use are easily made. A number of gastrointestinal peptides or their analogues for use in clinical studies are available from commercial sources (see Table 7). Somatostatin is the first gut peptide to successfully complete development and yield a pharmaceutical compound with a broad range of action. Several of the peptides discussed in this article have similar potential. TRH stands out as a candidate because of its effectiveness in the treatment of experimental spinal cord injury and a variety of shock states. Such a broad range of action in critical fields may justify the intensive development required to yield potent, long-acting, and highly specific analogues. Similarly, the antimetastatic and immunostimulant properties of the enkephalins offer promise for new therapies in the treatment of AIDS, ARC, and cancer. Studies with amylin may lead to new and more precise regimens of blood sugar control in insulin-dependent diabetics and could in turn, prevent some of the worst long-term effects of the disease. The development of effective intranasal forms of GHRH could spare children with GH-GHRH deficiency the distress of repeated injections and help to prevent excessive GH blood levels. Secretin, glucagon, or CGRP might be used one day in cardiovascular emergencies, and VIP or its analogues could prove effective in the treatment of asthma. Although preliminary results with many of these peptides are

  15. [Proteolysis of semax analogues with different N-terminal amino acids by aminopeptidases].

    PubMed

    Shevchenko, K V; V'iunova, T V; Nagaev, I Iu; Andreeva, L A; Alfeeva, L Iu; Miasoedov, N F

    2011-01-01

    Proteolysis of semax (Met-Glu-His-Phe-Pro-Gly-Pro, Sem) and its analogues ([Ala1]Sem, [Gly1]Sem, [Thr1]Sem, [Trp1]Sem) that are differ from semax in substitution of N-terminal Met residue were studied. It is shown that such replacement changes the rate of peptides degradation by N-aminopeptidases (EC 3.4.11.2, Sigma, Type VI, 9.2 units. Akt. / mg). [Ala1]Sem, [Gly1]Sem and [Thr1]Sem semax analogues proved to be more stable to proteolysis than semax (Sem), and their initial product of proteolysis is His-Phe-Pro-Gly-Pro (Sem-5). For triptophan analogue both Glu-His-Phe-Pro-Gly-Pro (Sem-6) and Sem-5 product are formed in similar quantities. It is found that all investigated analogues can be used as inhibitors in Sem proteolysis.

  16. Use of a fluorescent radiolabeled triacylglycerol as a substrate for lipoprotein lipase and hepatic triglyceride lipase

    SciTech Connect

    Dousset, N.; Negre, A.; Salvayre, R.; Rogalle, P.; Dang, Q.Q.; Douste-Blazy, L.

    1988-06-01

    A fluorescent radiolabeled triacylglycerol has been synthesized by using a fluorescent fatty acid (pyrene decanoic acid) and a radiolabeled oleic acid. This analog of the natural substrate, 1(3)pyrene decanoic-2,3 (1,2)-dioleoyl-sn-glycerol, has been tested as substrate for determining lipoprotein lipase and hepatic triacylglycerol lipase activities in post-heparin plasma. Optimal conditions for the determination of the two post-heparin plasma lipases were similar to those using radiolabeled triolein. Using this substrate, both post-heparin lipases exhibited their characteristic properties (pH optimum and effect of inhibitors) and attacked external ester bonds (1 or 3) containing pyrene decanoic and oleic acids at a similar rate.

  17. Microreactor and method for preparing a radiolabeled complex or a biomolecule conjugate

    DOEpatents

    Reichert, David E; Kenis, Paul J. A.; Wheeler, Tobias D; Desai, Amit V; Zeng, Dexing; Onal, Birce C

    2015-03-17

    A microreactor for preparing a radiolabeled complex or a biomolecule conjugate comprises a microchannel for fluid flow, where the microchannel comprises a mixing portion comprising one or more passive mixing elements, and a reservoir for incubating a mixed fluid. The reservoir is in fluid communication with the microchannel and is disposed downstream of the mixing portion. A method of preparing a radiolabeled complex includes flowing a radiometal solution comprising a metallic radionuclide through a downstream mixing portion of a microchannel, where the downstream mixing portion includes one or more passive mixing elements, and flowing a ligand solution comprising a bifunctional chelator through the downstream mixing portion. The ligand solution and the radiometal solution are passively mixed while in the downstream mixing portion to initiate a chelation reaction between the metallic radionuclide and the bifunctional chelator. The chelation reaction is completed to form a radiolabeled complex.

  18. Biodistribution of the Radiolabeled Anti III {beta}-Tubulin scFv Fragment in Mice

    SciTech Connect

    Kleinova, Veronika; Svecova, H.; Chaloupkova, H.; Kranda, K.; Fiser, M.

    2007-11-26

    For studies of new potential radiopharmaceutical such as radiolabeled compound, the biodistribution exoeriments are essential to describe behavior of the substance in organism. The specific binding of the scFv fragment of the monoclonal antibody TU-20 to the C-end of the class III {beta}-tubulin makes this substance useful as a potential diagnostics for in vivo neurodegenerative diseases determination. To examine this hypothesis, scFv was radio-labeled with {sup 125}I and {sup 123}I, and its biochemical properties were studied. The in vivo bio-distribution confirmed the expected elimination behavior of the radio-labeled scFv TU-20 in mice. The bi-exponential model for two-phase clearance to determine short phase half-life t{sub 1/2{alpha}} and long phase half-life t{sub 1/2{beta}} values was used to evaluate the experimental data.

  19. Validation of radiolabeling of drug formulations for aerosol deposition assessment of orally inhaled products.

    PubMed

    Devadason, Sunalene G; Chan, Hak-Kim; Haeussermann, Sabine; Kietzig, Claudius; Kuehl, Philip J; Newman, Stephen; Sommerer, Knut; Taylor, Glyn

    2012-12-01

    Radiolabeling of inhaler formulations for imaging studies is an indirect method of determining lung deposition and regional distribution of drug in human subjects. Hence, ensuring that the radiotracer and drug exhibit similar aerodynamic characteristics when aerosolized, and that addition of the radiotracer has not significantly altered the characteristics of the formulation, are critical steps in the development of a radiolabeling method. The validation phase should occur during development of the radiolabeling method, prior to commencement of in vivo studies. The validation process involves characterization of the aerodynamic particle size distribution (APSD) of drug in the reference formulation, and of both drug and radiotracer in the radiolabeled formulation, using multistage cascade impaction. We propose the adoption of acceptance criteria similar to those recommended by the EMA and ISAM/IPAC-RS for determination of therapeutic equivalence of orally inhaled products: (a) if only total lung deposition is being quantified, the fine particle fraction ratio of both radiolabeled drug and radiotracer to that of the reference drug should fall between 0.85 and 1.18, and (b) if regional lung deposition (e.g., outer and inner lung regions) is to be quantified, the ratio of both radiolabeled drug and radiotracer to reference drug on each impactor stage or group of stages should fall between 0.85 and 1.18. If impactor stages are grouped together, at least four separate groups should be provided. In addition, while conducting in vivo studies, measurement of the APSD of the inhaler used on each study day is recommended to check its suitability for use in man.

  20. Design and activity of novel lactoferrampin analogues against O157:H7 enterohemorrhagic Escherichia coli.

    PubMed

    Cruz, Jenniffer; Ortiz, Claudia; Guzmán, Fanny; Cárdenas, Constanza; Fernandez-Lafuente, Roberto; Torres, Rodrigo

    2014-04-01

    Lactoferrampin 265-284 (LFampin 265-284) is a peptide consisting of residues 265-284 of N1-domain of bovine Lactoferrin (LF). This peptide has several cationic groups in the C-terminal lobe, exhibiting an antibacterial activity against a wide range of microorganisms. However, LFampin 265-284 exhibits low antimicrobial activity against the O157:H7 enterohaemorrhagic Escherichia coli (EHEC O157:H7) when compared with Lactoferrin chimera and Lactoferricin. Here, we have designed three analogues of LFampin 265-284 based on the distribution of cationic groups, hydrophobicity, size, and sequence. Analogues were synthesized by solid phase chemistry using Fmoc methodology obtaining peptides with 95% purity. All peptides maintain the ability to adopt helical conformations (checked by circular dichroism spectra and molecular simulations). Some of these analogues exhibited a significant increase in antimicrobial activity by counting colony forming units against EHEC O157:H7 compared to native LFampin 265-284, with MIC of 10 and 40 µM for 264G-D265K and 264G-D265K/S272R, respectively. The incorporation of a GKLI sequence in the N-terminal lobe increased dramatically its antibacterial activity, an effect which has been attributed to the addition of cationic groups in the N-terminal side that may stabilize the helical conformation of the new designed peptides.

  1. Cell-free system responsible for internal radiolabeling of glycopeptidolipids of the Mycobacterium avium complex.

    PubMed Central

    Ramasesh, N; Wright, E L; Barrow, W W

    1992-01-01

    Internal radiolabeling of serotype-specific glycopeptidolipids with [14C]mannose was accomplished with a cell-free system derived from serotype 20 of the Mycobacterium avium complex. Similar radiolabeling was not apparent with a cell-free system derived from the rough colony variant, previously shown to be devoid of glycopeptidolipids. Although a comparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein analysis of the parent and rough variant strains revealed a close similarity, there were some proteins unique to the parent strain. Images PMID:1729193

  2. Effect of atropine on oral clearance of a radiolabeled sulfur colloid

    SciTech Connect

    LaForce, F.M.; Thompson, B.; Trow, R.

    1984-11-01

    Physical clearance is an important oral defense mechanism against gram-negative rods. The authors describe a simple technique that uses commercially available technetium-99m sulfur colloid to measure oral clearance. Technetium-99m sulfur colloid was sprayed into the mouth, and clearance was measured as the percent decrease in radiolabel counts over 2 hours using a radioisotope camera. Results using this technique compared favorably with clearance data using Tc-99m radiolabeled Escherichia coli. Atropine significantly decreased oral clearance rates of the colloid. Decreased clearance may be an important risk factor in the development of gram-negative rod colonization in hospitalized patients. 15 references, 3 figures.

  3. Bridged Analogues for p53-Dependent Cancer Therapy Obtained by S-Alkylation

    PubMed Central

    Micewicz, Ewa D.; Sharma, Shantanu; Waring, Alan J.; Luong, Hai T.; McBride, William H.; Ruchala, Piotr

    2015-01-01

    A small library of anticancer, cell-permeating, stapled peptides based on potent dual-specific antagonist of p53–MDM2/MDMX interactions, PMI-N8A, was synthesized, characterized and screened for anticancer activity against human colorectal cancer cell line, HCT-116. Employed synthetic modifications included: S-alkylation-based stapling, point mutations increasing hydrophobicity in key residues as well as improvement of cell-permeability by introduction of polycationic sequence(s) that were woven into the sequence of parental peptide. Selected analogue, ArB14Co, was also tested in vivo and exhibited potent anticancer bioactivity at the low dose (3.0 mg/kg). Collectively, our findings suggest that application of stapling in combination with rational design of polycationic short analogues may be a suitable approach in the development of physiologically active p53–MDM2/MDMX peptide inhibitors. PMID:26957954

  4. Flexible or fixed: a comparative review of linear and cyclic cancer-targeting peptides.

    PubMed

    Roxin, Áron; Zheng, Gang

    2012-08-01

    Peptides can serve as versatile cancer-targeting ligands and have been used for clinically relevant applications such as cancer imaging and therapy. A current and long-standing focus within peptide research is the creation of structurally constrained peptides generated through cyclization. Cyclization is envisioned to enhance the selective binding, uptake, potency and stability of linear precursors. This review compares closely related linear and cyclic peptides in these respects. Peptide cyclization generally improves the selective binding and stability of linear precursors; however, not all cyclization strategies and constrained geometries enhance these properties to the same extent. In some instances, linear analogues actually have better cancer-targeting properties compared with their cyclic counterparts. Although cyclization does not necessarily improve the cancer-targeting properties of linear analogues, cyclic peptides may obtain properties that allow them to be used for additional applications. This review aims to convey the advantages and limitations of cyclic cancer-targeting peptides.

  5. Peptide identification

    DOEpatents

    Jarman, Kristin H [Richland, WA; Cannon, William R [Richland, WA; Jarman, Kenneth D [Richland, WA; Heredia-Langner, Alejandro [Richland, WA

    2011-07-12

    Peptides are identified from a list of candidates using collision-induced dissociation tandem mass spectrometry data. A probabilistic model for the occurrence of spectral peaks corresponding to frequently observed partial peptide fragment ions is applied. As part of the identification procedure, a probability score is produced that indicates the likelihood of any given candidate being the correct match. The statistical significance of the score is known without necessarily having reference to the actual identity of the peptide. In one form of the invention, a genetic algorithm is applied to candidate peptides using an objective function that takes into account the number of shifted peaks appearing in the candidate spectrum relative to the test spectrum.

  6. Radiolabelled D2 agonists as prolactinoma imaging agents

    SciTech Connect

    Otto, C.A.

    1989-08-01

    During the past year, further studies on mAChR were conducted. These studies included verification of the difference in pituitary distribution based on ligand charge. The pituitary localization of TRB. A neutral mAChR ligand, was verified. The lack of QNB blockade of TRB uptake was tested by blockage with scopolamine, another mAChR antagonist and by testing the effect in a different strain of rat. Neither scopolamine or change of rat strain had any effect. We concluded that TRB uptake in pituitary is not a receptor-mediated process. Further studies were conducted with an additional quaternized mAChR ligand: MQNB. Pituitary localization of MQNB, like MTRB, could be blocked by pretreatment with QNB. We have tentatively concluded that permanent charge on a mAChR antagonist changes the mechanism of uptake in the pituitary. Time course studies and the effects of DES on myocardial uptake are reported. A brief report on preliminary results of evaluation of quaternized mAChR ligands in the heart is included. In a limited series of such ligands, we have observed a single binding site and a difference in B{sub max} values: QNB competition studies yield larger B{sub max} values than studies with {sup 3}H-NMS. Progress in the synthesis of D{sub 2} agonists includes solving a synthetic problem and preparation of the cold'' analogue of N-0437 using procedures applicable to eventual synthesis with {sup 11}C-CH{sub 3}I. 2 refs., 5 figs., 1 tab.

  7. Exploring the ammonium and nitrate transport of marine phytoplankton with nutrient analogues

    SciTech Connect

    Balch, W.M.

    1985-01-01

    Radiolabelled methylamine, an ammonium analogue and chlorate, a nitrate analogue, were transported constitutely by laboratory and field populations of phytoplakton. There was no effect of light on the transport of methylamine or chlorate which is contrary to similar measurements made with /sup 15/N-NH/sub 4//sup +/ and /sup 15/N-NO/sub 3//sup -/. The discrepancy appears to result from the fact that the analogues are only transported, while /sup 15/N-NH/sub 4/ and /sup 15/N-NO/sub 3//sup -/ are both transported and assimilated. Transport of ammonium and nitrate appeared to be active; it was against typical values of algal electrochemical gradients. Influx and efflux rates of methylamine and chlorate were measured in pulse-chase experiments; efflux rates increased as intracellular pools filled and net uptake slowed after approximately one to six hours. The pulse-chase experiments indicated that methylamine and chlorate (hence ammonium and nitrate) were stored in two intracellular compartments of diatoms, probably the vacuole and cytoplasm. Laboratory and field experiments demonstrated that chlorate transport by phytoplankton was inhibited when ambient ammonium or nitrite concentrations were high.

  8. Al(OH)3 facilitated synthesis of water-soluble, magnetic, radiolabelled and fluorescent hydroxyapatite nanoparticles.

    PubMed

    Cui, X; Green, M A; Blower, P J; Zhou, D; Yan, Y; Zhang, W; Djanashvili, K; Mathe, D; Veres, D S; Szigeti, K

    2015-06-07

    Magnetic and fluorescent hydroxyapatite nanoparticles were synthesised using Al(OH)3-stabilised MnFe2O4 or Fe3O4 nanoparticles as precursors. They were readily and efficiently radiolabelled with (18)F. Bisphosphonate polyethylene glycol polymers were utilised to endow the nanoparticles with excellent colloidal stability in water and to incorporate cyclam for high affinity labelling with (64)Cu.

  9. 78 FR 23596 - Manufacturer of Controlled Substances, Notice of Application, American Radiolabeled Chemicals, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Drug Enforcement Administration Manufacturer of Controlled Substances, Notice of Application, American Radiolabeled Chemicals, Inc. Pursuant to Sec. 1301.33(a), Title 21 of the Code of Federal Regulations (CFR), this is notice that on March 11,...

  10. Radiolabeled Exosomes for the Early Detection of Metastases and to Predict Breast Cancer Premetastatic Niche

    DTIC Science & Technology

    2014-08-01

    2. REPORT TYPE Annual 3. DATES COVERED 1 Aug 2013 - 31 Jul 2014 4. TITLE AND SUBTITLE Radiolabeled Exosomes for the Early Detection of...proposed a a new approach for the early detection of metastatic disease in BC patients using cancer cell derived particles known as exosomes as a guide. We

  11. Iodine-125 radiolabeling of silver nanoparticles for in vivo SPECT imaging

    PubMed Central

    Chrastina, Adrian; Schnitzer, Jan E

    2010-01-01

    Silver nanoparticles are increasingly finding applications in medicine; however, little is known about their in vivo tissue distribution. Here, we have developed a rapid method for radiolabeling of silver nanoparticles with iodine-125 in order to track in vivo tissue uptake of silver nanoparticles after systemic administration by biodistribution analysis and single-photon emission computerized tomography (SPECT) imaging. Poly(N-vinyl-2 -pyrrolidone)-capped silver nanoparticles with an average size of 12 nm were labeled by chemisorption of iodine-125 with a > 80% yield of radiolabeling efficiency. Radiolabeled silver nanoparticles were intravenously injected in Balb/c mice, and the in vivo distribution pattern of these nanoparticles was evaluated by noninvasive whole-body SPECT imaging, which revealed uptake of the nanoparticles in the liver and spleen. Biodistribution analysis confirmed predominant accumulation of the silver nanoparticles in the spleen (41.5%ID/g) and liver (24.5%ID/g) at 24 h. Extensive uptake in the tissues of the reticuloendothelial system suggests that further investigation of silver nanoparticle interaction with hepatic and splenic tissues at the cellular level is critical for evaluation of the in vivo effects and potential toxicity of silver nanoparticles. This method enables rapid iodine-125 radiolabeling of silver nanoparticles with a specific activity sufficient for in vivo imaging and biodistribution analysis. PMID:20856841

  12. Measurement of Carbon Dioxide Production from Radiolabeled Substrates in Drosophila melanogaster

    PubMed Central

    Bland, Michelle L.

    2016-01-01

    The power of Drosophila genetics is increasingly being applied to questions of hormone signaling and metabolism and to the development of models of human disease in this organism. Sensitive methods for measurements of parameters such as metabolic rates are needed to drive the understanding of physiology and disease in small animals such as the fruit fly. The method described here assesses fuel oxidation in small numbers of adult flies fed food containing trace amounts of 14C-labeled substrates such as glucose or fatty acid. After the feeding period and any additional experimental manipulations, flies are transferred to short tubes capped with mesh, which are then placed in glass vials containing KOH-saturated filter paper that traps exhaled, radiolabeled CO2 generated from oxidation of radiolabeled substrates as potassium bicarbonate, KHCO3. This radiolabeled bicarbonate is measured by scintillation counting. This is a quantitative, reproducible, and simple approach for the study of fuel oxidation. The use of radiolabeled glucose, fatty acids, or amino acids allows determination of the contribution of these different fuel sources to energy metabolism under different conditions such as feeding and fasting and in different genetic backgrounds. This complements other approaches used to measure in vivo energy metabolism and should further the understanding of metabolic regulation. PMID:27404635

  13. Novel alpha-MSH peptide analogs for melanoma targeting

    NASA Astrophysics Data System (ADS)

    Flook, Adam Michael

    Skin cancer is the one of the most diagnosed cancers in the United States with increasing incidence over the past two decades. There are three major forms of skin cancer but melanoma is the deadliest. It is estimated that 76,690 new diagnoses of melanoma and 9,480 deaths will occur in 2013. Melanoma accounts for approximately 1.6% of all cancer related deaths and is the 5 th leading diagnosed cancer in the United States. The mean survival rate of patients diagnosed with metastatic melanoma is six months, with five year survival rates of less than 5%. In this project, we describe the design and characterization of novel melanoma-targeting peptide analogs for use in diagnostic imaging of both primary and metastatic melanoma lesions. Novel alpha-MSH peptide conjugates were designed to target the melanocortin-1 receptor present and over-expressed on melanoma cells. These peptides were synthesized and their in-vitro melanocortin-1 receptor binding affinities were established in murine melanoma cells. Once binding affinities were determined, the peptides were radiolabeled with 99mTc utilizing a novel direct radiolabeling technique developed in our laboratory. The peptides were purified via reverse-phase high performance liquid chromatography and in-vivo melanoma targeting and pharmacokinetic properties were determined in B16/F1 melanoma-bearing female C57BL/6 mice. Biodistribution and SPECT/CT imaging studies were performed with the promising 99m Tc-labeled peptide conjugates. All alpha-MSH peptide conjugates tested showed low nanomolar binding affinity for the melanocortin-1 receptor. All peptides were readily radiolabeld with 99mTc with greater than 95% radiochemical purity. All 99mTc-labeled peptides displayed high specific in-vivo melanoma tumor uptake while maintaining low normal organ accumulation, and were excreted through the urinary system in a timely fashion. In addition, all tested 99mTc-labeld alpha-MSH peptides demonstrated clear visualization of in

  14. Comparative studies on peptides representing the so-called tachykinin-like region of the Alzheimer Abeta peptide [Abeta(25-35)].

    PubMed Central

    El-Agnaf, O M; Irvine, G B; Fitzpatrick, G; Glass, W K; Guthrie, D J

    1998-01-01

    In an attempt to answer the question of whether or not the so-called tachykinin-like region of the Alzheimer beta-amyloid protein [Abeta(25-35)] can act as a tachykinin, the sequences Abeta(25-35), Abeta(25-35)amide and their norleucine-35 and phenylalanine-31 analogues were synthesized. These peptides were examined with ligand binding studies, electron microscopy, CD and NMR. In all cases some differences were found between the Abeta(25-35) analogue and the corresponding Phe31 peptide. In addition, in ligand displacement studies on tachykinin NK1 receptors, only the Phe31 analogue showed activity comparable to that of genuine tachykinins. We conclude that peptides based on Abeta(25-35) but with a Phe residue at position 31 do display properties typical of a tachykinin, but that peptides with Ile at this position do not. PMID:9820820

  15. Model Membrane and Cell Studies of Antimicrobial Activity of Melittin Analogues.

    PubMed

    Jamasbi, Elaheh; Mularski, Anna; Separovic, Frances

    2016-01-01

    Melittin is a 26 residue peptide and the major component of bee (Apis mellifera) venom. Although melittin has both anticancer and antimicrobial properties, utilization has been limited due to its high lytic activity against eukaryotic cells. The mechanism of this lytic activity remains unclear but several mechanisms have been proposed, including pore formation or a detergent like mechanism, which result in lysis of cell membranes. Several analogues of melittin have been synthesized to further understand the role of specific residues in its antimicrobial and lytic activity. Melittin analogues that have a proline residue substituted for an alanine, lysine or cysteine have been studied with both model membrane systems and living cells. These studies have revealed that the proline residue plays a critical role in antimicrobial activity and cytotoxicity. Analogues lacking the proline residue and dimers of these analogues displayed decreased cytotoxicity and minimum inhibition concentrations. Several mutant studies have shown that, when key substitutions are made, the resultant peptides have more activity in terms of pore formation than the native melittin. Designing analogues that retain antimicrobial and anticancer activity while minimizing haemolytic activity will be a promising way to utilize melittin as a potential therapeutic agent.

  16. cis-Peptide Bonds: A Key for Intestinal Permeability of Peptides? .

    PubMed

    Marelli, Udaya Kiran; Ovadia, Oded; Frank, Andreas Oliver; Chatterjee, Jayanta; Gilon, Chaim; Hoffman, Amnon; Kessler, Horst

    2015-10-19

    Recent structural studies on libraries of cyclic hexapeptides led to the identification of common backbone conformations that may be instrumental to the oral availability of peptides. Furthermore, the observation of differential Caco-2 permeabilities of enantiomeric pairs of some of these peptides strongly supports the concept of conformational specificity driven uptake and also suggests a pivotal role of carrier-mediated pathways for peptide transport, especially for scaffolds of polar nature. This work presents investigations on the Caco-2 and PAMPA permeability profiles of 13 selected N-methylated cyclic pentaalanine peptides derived from the basic cyclo(-D-Ala-Ala4 -) template. These molecules generally showed moderate to low transport in intestinal epithelia with a few of them exhibiting a Caco-2 permeability equal to or slightly higher than that of mannitol, a marker for paracellular permeability. We identified that the majority of the permeable cyclic penta- and hexapeptides possess an N-methylated cis-peptide bond, a structural feature that is also present in the orally available peptides cyclosporine A and the tri-N-methylated analogue of the Veber-Hirschmann peptide. Based on these observations it appears that the presence of N-methylated cis-peptide bonds at certain locations may promote the intestinal permeability of peptides through a suitable conformational preorganization.

  17. Heteroclitic properties of mixed alpha- and aza-beta3-peptides mimicking a supradominant CD4 T cell epitope presented by nucleosome.

    PubMed

    Dali, Hayet; Busnel, Olivier; Hoebeke, Johan; Bi, Lanrong; Decker, Patrice; Briand, Jean-Paul; Baudy-Floc'h, Michèle; Muller, Sylviane

    2007-04-01

    Recent studies have revealed that peptide analogues containing modified peptide bonds might replace poorly stable natural peptides in therapeutic strategies. Using the model peptide 88-99 of histone H4, which contains a supradominant epitope recognized by Th cells induced to nucleosomes, we have generated twelve analogues containing aza-beta(3)-amino acid residue substitutions. The ability of this new class of peptidomimetics corresponding to the Psi[CONHNRCH(2)] modification to be recognized by T cells primed with the parent peptide was examined in BALB/c mice. An Ala-scan study revealed that residues 88 to 92 were essential for keeping antigenic activity of the nominal peptide. In good agreement, the six aza-beta(3)-analogues encompassing substitutions in the region 89-92 were antigenically inactive. Analogues PsiG94 and PsiG99 were both antigenic and immunogenic, though at levels that were slightly lower to that of the parent peptide. However, the remaining analogues PsiR95, PsiL97, PsiY98 and PsiL97-Y98 were strongly recognized by T cells generated to the homologous peptides. The PsiL97-Y98 analogue, in particular, strongly activated CD4(+) T cells as visualized in CFSE dilution assay. T cells primed to these four analogues and recalled with the nominal peptide secreted high levels of either IL-2 (PsiR95, PsiY98) or IFN-gamma (PsiL97, PsiL97-Y98). This result, supported by molecular modeling, suggests that TCRs of T cells primed to these four analogues recognized the parent peptide associated with the MHC I-A(d)/I-E(d) molecules. Since these T cells produce a distinct cytokine pattern when they are recalled with the parent sequence, this new class of analogues may have valuable applications in the context of self-tolerance and autoimmunity.

  18. [Effect of modification of the N-terminal region of molecule on the expression of neotropic effect of semax analogues].

    PubMed

    Glazova, N Iu; Sebentsova, E A; Levitskaia, N G; Andreeva, L A; Alfeeva, L Iu; Kamenskiĭ, A A; Miasoedov, N F

    2005-01-01

    A comparative study of neotropic activity of semax (MEHFPGP), an analogue of the ACTH(4-10), and some of its derivatives in which the N-terminal methionine was modified or substituted with other amino acid residues was performed. The effect of these peptides on learning of albino rats in tests with positive (alimentary) and negative (pain) reinforcement was studied. In the case of modification of methionine by attachment of the gluconic-acid residue or substitution of methionine with lysine, the neotropic effect of the peptide was retained. The substitution of methionine with tryptophan or serine resulted in a decrease in the neotropic activity. The substitution of methionine with glycine, threonine, or alanine caused a complete loss of the neotropic activity of the peptide. Therefore, the amino acid residue located at position 1 of the heptapeptide analogue semax, plays a key role in retaining the neotropic effects of the peptide and determines the degree of their expression.

  19. Pharmacologic profiles of investigational kisspeptin/metastin analogues, TAK-448 and TAK-683, in adult male rats in comparison to the GnRH analogue leuprolide.

    PubMed

    Matsui, Hisanori; Masaki, Tsuneo; Akinaga, Yumiko; Kiba, Atsushi; Takatsu, Yoshihiro; Nakata, Daisuke; Tanaka, Akira; Ban, Junko; Matsumoto, Shin-ichi; Kumano, Satoshi; Suzuki, Atsuko; Ikeda, Yukihiro; Yamaguchi, Masashi; Watanabe, Tatsuya; Ohtaki, Tetsuya; Kusaka, Masami

    2014-07-15

    Kisspeptin/metastin, a hypothalamic peptide, plays a pivotal role in controlling gonadotropin-releasing hormone (GnRH) neurons, and we have shown that continuous subcutaneous administration of kisspeptin analogues suppresses plasma testosterone in male rats. This study examined pharmacologic profiles of investigational kisspeptin analogues, TAK-448 and TAK-683, in male rats. Both analogues showed high receptor-binding affinity and potent and full agonistic activity for rat KISS1R, which were comparable to natural peptide Kp-10. A daily subcutaneous injection of TAK-448 and TAK-683 (0.008-8μmol/kg) for consecutive 7 days initially induced an increase in plasma luteinizing hormone and testosterone levels; however, after day 7, plasma hormone levels and genital organ weights were reduced. Continuous subcutaneous administrations of TAK-448 (≥10pmol/h, ca. 0.7nmol/kg/day) and TAK-683 (≥30pmol/h, ca. 2.1nmol/kg/day) induced a transient increase in plasma testosterone, followed by abrupt reduction of plasma testosterone to castrate levels within 3-7 days. This profound testosterone-lowering effect was sustained throughout 4-week dosing periods. At those dose levels, the weights of the prostate and seminal vesicles were reduced to castrate levels. These suppressive effects of kisspeptin analogues were more rapid and profound than those induced by the GnRH agonist analogue leuprolide treatment. In addition, TAK-683 reduced plasma prostate specific antigen (PSA) in the JDCaP androgen-dependent prostate cancer rat model. Thus, chronic administration of kisspeptin analogues may hold promise as a novel therapeutic approach for suppressing reproductive functions and hormone-related diseases such as prostate cancer. Further studies are warranted to elucidate clinical significance of TAK-448 and TAK-683.

  20. Receptor-mediated uptake of boron-rich neuropeptide y analogues for boron neutron capture therapy.

    PubMed

    Ahrens, Verena M; Frank, René; Boehnke, Solveig; Schütz, Christian L; Hampel, Gabriele; Iffland, Dorothée S; Bings, Nicolas H; Hey-Hawkins, Evamarie; Beck-Sickinger, Annette G

    2015-01-01

    Peptidic ligands selectively targeting distinct G protein-coupled receptors that are highly expressed in tumor tissue represent a promising approach in drug delivery. Receptor-preferring analogues of neuropeptide Y (NPY) bind and activate the human Y1 receptor subtype (hY1 receptor), which is found in 90% of breast cancer tissue and in all breast-cancer-derived metastases. Herein, novel highly boron-loaded Y1 -receptor-preferring peptide analogues are described as smart shuttle systems for carbaboranes as (10) B-containing moieties. Various positions in the peptide were screened for their susceptibility to carbaborane modification, and the most promising positions were chosen to create a multi-carbaborane peptide containing 30 boron atoms per peptide with excellent activation and internalization patterns at the hY1 receptor. Boron uptake studies by inductively coupled plasma mass spectrometry revealed successful uptake of the multi-carbaborane peptide into hY1 -receptor-expressing cells, exceeding the required amount of 10(9) boron atoms per cell. This result demonstrates that the NPY/hY receptor system can act as an effective transport system for boron-containing moieties.

  1. Mammalian folylpoly-. gamma. -glutamate synthetase. 3. Specificity for folate analogues

    SciTech Connect

    George, S.; Cichowicz, D.J.; Shane, B.

    1987-01-27

    A variety of folate analogues were synthesized to explore the specificity of the folate binding site of hog liver folypolyglutamate synthetase and the requirements for catalysis. Modifications of the internal and terminal glutamate moieties of folate cause large drops in on rates and/or affinity for the protein. The only exceptions are glutamine, homocysteate, and ornithine analogues, indicating a less stringent specificity around the delta-carbon of glutamate. It is proposed that initial folate binding to the enzyme involves low-affinity interactions at a pterin and a glutamate site and that the first glutamate bound is the internal residue adjacent to the benzoyl group. Processive movement of the polyglutamate chain through the glutamate site and a possible conformational change in the protein when the terminal residue is bound would result in tight binding and would position the ..gamma..-carboxyl of the terminal glutamate in the correct position for catalysis. The 4-amino substitution of folate increases the on rate for monoglutamate derivatives but severely impairs catalysis with diglutamate derivatives. Pteroylornithine derivatives are the first potent and specific inhibitors of folylpolyglutamate synthetase to be identified and may act as analogues of reaction intermediates. Other folate derivatives with tetrahedral chemistry replacing the peptide bond, such as pteroyl-..gamma..-glutamyl-(psi,CH/sub 2/-NH)-glutamate, retain affinity for the protein but are considerably less effective inhibitors than the ornithine derivatives. Enzyme activity was assayed using (/sup 14/C)glutamate.

  2. Receptors for GRP/bombesin-like peptides in the rat forebrain

    SciTech Connect

    Wolf, S.S.; Moody, T.W.

    1985-01-01

    Binding sites in the rat forebrain were characterized using ( SVI-Tyr4)bombesin as a receptor probe. Pharmacology experiments indicate that gastrin releasing peptide (GRP) and the GRP fragments GRP as well as Ac-GRP inhibited radiolabeled (Tyr4)bombesin binding with high affinity. Biochemistry experiments indicated that heat, N-ethyl maleimide or trypsin greatly reduced radiolabeled (Tyr4)bombesin binding. Also, autoradiographic studies indicated that highest grain densities were present in the stria terminalis, periventricular and suprachiasmatic nucleus of the hypothalamus, dorsomedial and rhomboid thalamus, dentate gyrus, hippocampus and medial amygdaloid nucleus. The data suggest that CNS protein receptors, which are discretely distributed in the rat forebrain, may mediate the action of endogenous GRP/bombesin-like peptides.

  3. Comparison of the indirect immunobead, radiolabeled, and immunofluorescence assays for immunoglobulin G serum antibodies to human sperm

    SciTech Connect

    Haas, G.G. Jr.; D'Cruz, O.J.; DeBault, L.E. )

    1991-02-01

    The relative sensitivities of the indirect immunobead test, the indirect flo cytometric immunofluorescence assay, and an indirect radiolabeled antiglobulin assay were compared. Eighteen immunobead test positive sera and 18 negative sera were used as the standard for the other two assays. Of the 18 positive sera, 14 (77%) and 5 (27%) were positive in the immunofluorescence assay and the radiolabeled antiglobulin assay, respectively. Four (22%) of the low titer immunobead test positive sera were negative by both the immunofluorescence assay and the radiolabeled antiglobulin assay. However, there was a significant positive correlation between the results of the immunofluorescence assay and the radiolabeled antiglobulin assay (r = 0.73) and between the results of the radiolabeled antiglobulin assay and the titer of the immunobead test (r = 0.82). The use of an unselected sperm population in the radiolabeled antiglobulin assay and the classical indirect immunofluorescence method using methanol-fixed sperm gave false-positive results in the radiolabeled antiglobulin assay and the immunofluorescence assay. These results suggested that immunoglobulin G antisperm antibody positive sera may be reactive both to sperm surface and internalized sperm antigens.

  4. Labeling and distribution of linear peptides identified using in vivo phage display selection for tumors.

    PubMed

    Kennel, S J; Mirzadeh, S; Hurst, G B; Foote, L J; Lankford, T K; Glowienka, K A; Chappell, L L; Kelso, J R; Davern, S M; Safavy, A; Brechbiel, M W

    2000-11-01

    To develop targeting molecules to be used for vascular targeting of short half-lived alpha-emitters for radioimmunotherapy, linear peptide phage display libraries were selected in vivo for binding to IC-12 rat tracheal tumors growing in severe combined immune deficient mice. After three rounds of selection, 15 phage clones were analyzed for DNA sequence, and the deduced translation products of cDNA inserts were compared. Three consensus sequences were chosen from three separate experimental selection series and peptides of these sequences with added -gly-gly-tyr were obtained. Peptides were radiolabeled on tyrosine with (125)I and the biodistribution in tumor-bearing mice was determined. The radioiodinated peptides were stable in vitro and when injected in tumor-bearing mice approximately 3.0 %ID/g accumulated in the tumor; however, much of the (125)I was found in the gastrointestinal tract and thyroid, indicative of dehalogenation of the labeled peptide. Radiolabeling peptide 2 with N-succinimidyl-3-(125)I-iodobenzoate resulted in faster excretion, which in turn resulted in lower levels in tumor and other organs, especially thyroid and gastrointestinal tract. Peptide 2 was derivatized with the bifunctional isothiocyanates of cyclohexyl-B diethylenetriaminepentaacetic acid (DTPA) or CHX-A" DTPA by direct conjugation or with a hydroxylamine derivative of 1B4M-DTPA (2-(p-[O-(carboxamylmethyl)hydroxylamine]benzyl)-6-methyl-diethylenetriamine-N,N,N',N",N"-pentaacetic acid ) coupled at the N-terminus. The primary molecular species in the conjugated products were shown by mass spectrometry to have one DTPA per peptide. Peptide chelate conjugates were radiolabeled with (213)Bi and the products tested for biodistribution in tumor-bearing mice. The data show that chelation of (213)Bi to peptides was accomplished by both the direct method of DTPA attachment and by the method using the linker at the N-terminus. Only small amounts of peptide accumulated at tumor sites. We

  5. Specific receptor binding of atrial natriuretic peptide to rat renal cortex

    SciTech Connect

    Ogura, T.; Mitsui, T.; Ogawa, N.; Ota, Z.

    1985-09-01

    Radiolabeled receptor assay (RRA) of atrial natriuretic peptide (ANP) was studied in rat kidney membranes. Binding of ( SVI)-ANP to membrane preparations of rat whole kidney was saturated and show a high affinity. Furthermore, renal cortex membrane had a higher affinity for ANP binding site than renal medulla membrane. This high affinity ANP receptor site in renal cortex membrane indicated that ANP controlled the balance of water and sodium excretion due to this receptor site in the kidney.

  6. Surfactin analogues produced by Bacillus subtilis strains grown on rapeseed cake

    NASA Astrophysics Data System (ADS)

    Jajor, Paweł; Piłakowska-Pietras, Dorota; Krasowska, Anna; Łukaszewicz, Marcin

    2016-12-01

    Microbiologically produced surface acting compounds (biosurfactants) have very interesting properties with many potential industrial applications. Lipopeptides is a particularly promising group of biosurfactants in respect to the potentially huge number of various chemical structures. The chemical diversity results from fatty acid moiety (e.g. length, saturation, branching or hydroxylation) and type and sequence of the amino acids in the peptide chain. The limiting factor for the design and analysis of various lipopeptides is the ability of the targeted biosynthesis. Biosynthesis of particular lipopeptides may be potentially achieved by strain selection, culture conditions, or molecular engineering. The well-known lipopeptedes (surfactins, iturins, and fengycins) producer is B. subtilis. The aim of this study was to study targeted surfactin structural analogues biosynthesis in response to culture conditions in view of the design and production of tailor-made lipopeptides. Two B. subtilis strains (KB1 and #309) were tested for surfactin production. Both strains produced a mixture of five major surfactin analogues with the number of carbons in an alkyl chain ranging from 12 to 16. The two strains differed with respect to their oxygen demand for optimal surfactin biosynthesis (lower oxygen demand for KB1). The amount of air influenced the relative ratios of surfactin analogues. Lower oxygen amount decreased the share of C15 analogues while it increased the share of C12 analogues. Thus, the biosynthesis of a desired surfactin analogue may controlled by both strain and culture conditions.

  7. Novel synthesis of cyclic amide-linked analogues of angiotensins II and III.

    PubMed

    Matsoukas, J M; Hondrelis, J; Agelis, G; Barlos, K; Gatos, D; Ganter, R; Moore, D; Moore, G J

    1994-09-02

    Cyclic amide-linked angiotension II (ANGII) analogues have been synthesized by novel strategies, in an attempt to test the ring clustering and the charge relay bioactive conformation recently suggested. These analogues were synthesized by connecting side chain amino and carboxyl groups at positions 1 and 8, 2 and 8, 3 and 8, and 3 and 5, N-terminal amino and C-terminal carboxyl groups at positions 1 and 8, 2 and 8, and 4 and 8, and side chain amino to C-terminal carboxyl group at positions 1 and 8. All these analogues were biologically inactive, except for cyclic [Sar1, Asp3, Lys5]ANGII (analogue 10) which had high contractile activity in the rat uterus assay (30% of ANGII) and [Lys1, Tyr(Me)4, Glu8]ANGII (analogue 7) which had weak antagonist activity (PA2 approximately 6). Precyclic linear peptides synthesized using 2-chlorotrityl chloride resin and N alpha-Fmoc-amino acids with suitable side chain protection were obtained in high yield and purity and were readily cyclized with benzotriazol-1-yloxytris(dimethylamino)-phosphonium hexafluorophosphate as coupling reagent. Molecular modeling suggests that the ring structure of the potent analogue can be accommodated in the charge relay conformation proposed for ANGII.

  8. A photoactive isoprenoid diphosphate analogue containing a stable phosphonate linkage: synthesis and biochemical studies with prenyltransferases

    PubMed Central

    DeGraw, Amanda J.; Zhao, Zongbao; Strickland, Corey L.; Taban, A. Huma; Hsieh, John; Michael, Jefferies; Xie, Wenshuang; Shintani, David; McMahan, Colleen; Cornish, Katrina; Distefano, Mark D.

    2008-01-01

    A number of biochemical processes rely on isoprenoids, including the post-translational modification of signaling proteins and the biosynthesis of a wide array of compounds. Photoactivatable analogues have been developed to study isoprenoid utilizing enzymes such as the isoprenoid synthases and prenyltransferases. While these initial analogues proved to be excellent structural analogues with good cross linking capability, they lack the stability needed when the goals include isolation of cross-linked species, tryptic digestion, and subsequent peptide sequencing. Here, the synthesis of a benzophenone-based farnesyl diphosphate analogue containing a stable phosphonophosphate group is described. Inhibition kinetics, photolabeling experiments, as well as x-ray crystallographic analysis with a protein prenyltransferase are described, verifying this compound as a good isoprenoid mimetic. In addition, the utility of this new analogue was explored by using it to photoaffinity label crude protein extracts obtained from Hevea brasiliensis latex. Those experiments suggest that a small protein, Rubber Elongation Factor, interacts directly with farnesyl diphosphate during rubber biosynthesis. These results indicate that this benzophenone-based isoprenoid analogue will be useful for identifying enzymes that utilize farnesyl diphosphate as a substrate. PMID:17477573

  9. Neuronal Analogues of Conditioning Paradigms

    DTIC Science & Technology

    1984-04-24

    Although the mechanisms of interneuronal communication have been well established, the changes underlying most forms of learning have thus far eluded...stimulating electrodes on one of the connectives was adjusted so as to produce a small excitatory postsynaptic potential ( EPSP ) in the impaled cell...two stimuli would constitute a neuronal analogue of conditioning by producing an increased EPSP in response to the test stimulus alone. If so, then

  10. Dynamics and aggregation of the peptide ion channel alamethicin. Measurements using spin-labeled peptides.

    PubMed Central

    Archer, S J; Ellena, J F; Cafiso, D S

    1991-01-01

    Two spin-labeled derivatives of the ion conductive peptide alamethicin were synthesized and used to examine its binding and state of aggregation. One derivative was spin labeled at the C-terminus and the other, a leucine analogue, was spin labeled at the N-terminus. In methanol, both the C and N terminal labeled peptides were monomeric. In aqueous solution, the C-terminal derivative was monomeric at low concentrations, but aggregated at higher concentrations with a critical concentration of 23 microM. In the membrane, the C-terminal label was localized to the membrane-aqueous interface using 13C-NMR, and could assume more than one orientation. The membrane binding of the C-terminal derivative was examined using EPR, and it exhibited a cooperativity seen previously for native alamethicin. However, this cooperativity was not the result of an aggregation of the peptide in the membrane. When the spectra of either the C or N-terminal labeled peptide were examined over a wide range of membrane lipid to peptide ratios, no evidence for aggregation could be found and the peptides remained monomeric under all conditions examined. Because electrical measurements on this peptide provide strong evidence for an ion-conductive aggregate, the ion-conductive form of alamethicin likely represents a minor fraction of the total membrane bound peptide. PMID:1717016

  11. Peptides for diagnosis and treatment of colorectal cancer.

    PubMed

    Shapira, S; Fokra, A; Arber, N; Kraus, S

    2014-01-01

    Colorectal cancer (CRC) is a major health concern worldwide, as it is the third most frequently diagnosed cancer and the second leading cause of cancer-related death. There are a number of treatment options for CRC, however many of them are disappointing. Therefore, significant efforts are directed towards the development of new biological therapies with improved efficacy. The use of peptides in CRC treatment holds promise as emerging novel anti-cancer agents. Targeted therapy based on the use of peptides that can directly target tumor cells without affecting normal cells is evolving as an alternative strategy to conventional therapies and particularly, chemotherapy. The main advantages of peptides are their relatively easy and rapid synthesis process, and the vast possibilities for chemical modifications that can be exploited for novel peptide design and improved delivery. Peptides can be utilized directly as cytotoxic agents or indirectly as they can act as carriers of cytotoxic agents, drugs, or radioisotopes by specifically targeting tumor cells. They can also be used for diagnostic purposes. Current research focuses on developing peptides that can serve as tumor targeting moieties, permeabilize membranes to induce cytotoxicy, radiolabeled peptides, and peptide vaccines. In addition, improving targeting to tumors, reducing side effects, due to non-specific toxicity, and unraveling the pharmacokinetic characteristics of potential peptides, for either therapeutic or diagnostic use, are also subjects of intensive investigation. This review provides a brief overview on the role of peptides in CRC diagnosis and therapy that are currently being investigated, and their potential applications in the clinical setting.

  12. Synthesis, 68Ga-Radiolabeling, and Preliminary In Vivo Assessment of a Depsipeptide-Derived Compound as a Potential PET/CT Infection Imaging Agent

    PubMed Central

    Mokaleng, Botshelo B.; Ebenhan, Thomas; Ramesh, Suhas; Govender, Thavendran; Kruger, Hendrik G.; Hazari, Puja P.; Mishra, Anil K.; Marjanovic-Painter, Biljana; Zeevaart, Jan R.; Sathekge, Mike M.

    2015-01-01

    Noninvasive imaging is a powerful tool for early diagnosis and monitoring of various disease processes, such as infections. An alarming shortage of infection-selective radiopharmaceuticals exists for overcoming the diagnostic limitations with unspecific tracers such as 67/68Ga-citrate or 18F-FDG. We report here TBIA101, an antimicrobial peptide derivative that was conjugated to DOTA and radiolabeled with 68Ga for a subsequent in vitro assessment and in vivo infection imaging using Escherichia coli-bearing mice by targeting bacterial lipopolysaccharides with PET/CT. Following DOTA-conjugation, the compound was verified for its cytotoxic and bacterial binding behaviour and compound stability, followed by 68Gallium-radiolabeling. µPET/CT using 68Ga-DOTA-TBIA101 was employed to detect muscular E. coli-infection in BALB/c mice, as warranted by the in vitro results. 68Ga-DOTA-TBIA101-PET detected E. coli-infected muscle tissue (SUV = 1.3–2.4) > noninfected thighs (P = 0.322) > forearm muscles (P = 0.092) > background (P = 0.021) in the same animal. Normalization of the infected thigh muscle to reference tissue showed a ratio of 3.0 ± 0.8 and a ratio of 2.3 ± 0.6 compared to the identical healthy tissue. The majority of the activity was cleared by renal excretion. The latter findings warrant further preclinical imaging studies of greater depth, as the DOTA-conjugation did not compromise the TBIA101's capacity as targeting vector. PMID:25699267

  13. Structural requirements for human inducible nitric oxide synthase substrates and substrate analogue inhibitors.

    PubMed

    Grant, S K; Green, B G; Stiffey-Wilusz, J; Durette, P L; Shah, S K; Kozarich, J W

    1998-03-24

    Inducible nitric oxide synthase (iNOS; EC 1.14.13.39) catalyzes the NADPH-dependent oxidation of one of the free guanidino nitrogens of L-Arg to form nitric oxide and L-citrulline. Analogues of L-Arg and the inhibitor, L-N6-(1-iminoethyl)lysine, were used to define structural elements required for the binding and catalysis of compounds. L-Arg analogues with sequentially shorter methylene spacing between the guanidino group and the amino acid portion of the molecule were not iNOS substrates but were reversible inhibitors. L-Arg analogues such as agmatine with a hydroxyl substitution at the 2-amino position were substrates. Desaminoarginine was not a substrate but a reversible inhibitor. Desaminoarginine, agmatine, and argininic acid bound to the enzyme to give type I difference spectra similar to that of L-Arg. The amidino compounds L-N6-(1-iminoethyl)lysine, L-N5-(1-iminoethyl)ornithine, and N5-(1-iminoethyl)cadaverdine, but not N6-(1-iminoethyl)-6-aminocaproic acid, were NADPH-dependent, irreversible inactivators of iNOS. For both the L-Arg and L-N6-(1-iminoethyl)lysine analogues, the 2-amino group appeared to play an important role in catalytic events leading to either substrate turnover or mechanism-based inactivation. Inactivation of iNOS by L-N6-(1-iminoethyl)lysine was NADPH- and dioxygen-dependent, but low incorporation of radiolabel with DL--4, 5-3H]-N6-(1-iminoethyl)lysine indicates that the mechanism of enzyme inactivation is not covalent modification of the protein.

  14. Effect of tellurium position on the myocardial uptake of radioiodinated 18-iodotellura-17-octadecenoic acid analogues

    SciTech Connect

    Knapp, F.F. Jr.; Srivastava, P.C.; Callahan, A.P.; Cunningham, E.B.; Kabalka, G.W.; Sastry, K.A.

    1984-01-01

    The effect of tellurium (Te) position on myocardial specificity and retention of fatty acids in which radioiodide is stabilized as a trans-(E)-vinyl iodide has been evaluated in rats. Five analogues of 18-iodo-17-octadecenoic acid (ICH . CH-R-Te-R'-COOH) with Te at positions 5, 7, 9, 11, and 13 were prepared by coupling of a trans-diiodoalkene (ICH . CH-R-I) with the requisite sodium ((alkoxycarbonyl)alkyl)telluride substrate (NaTe-R'-COOR''; R'' . Me or Et), followed by basic hydrolysis. By varying R and R', a series of analogues with a chain length of 18 carbon atoms was prepared. The telluride substrates were generated in situ by NaBH4 reduction of the corresponding ditellurides, and the diiodoalkenes were prepared by sodium iodide-chloramine-T treatment of the corresponding vinylboronic acids ((HO)2BCH . CH-R-I)). The vinylboronic acids were prepared by treatment of the terminal acetylenes (HC identical to C-R-I), synthesized from commercially available materials, with catecholborane. All new compounds were analyzed by TLC, NMR, MS, and elemental analyses. The /sup 125/I analogues ((E)-/sup 125/ICH . CH-R-Te-R'-COOH) were prepared in the same manner and evaluated in rats (four per group). Heart uptake and retention were dependent upon the Te position. The analogue with Te at position 5 showed the most pronounced (5-min values) heart uptake (3.7-4.1 dose/g), myocardial retention, and heart/blood ratios (37:1) and is a candidate for radiolabeling with /sup 123/I and further evaluation as a myocardial imaging agent.

  15. Methods for MAG3 conjugation and 99mTc radiolabeling of biomolecules.

    PubMed

    Wang, Yi; Liu, Guozheng; Hnatowich, Donald J

    2006-01-01

    The chelator mercaptoacetyltriglycine (MAG3) forms a single stable chelate with technetium-99m (99mTc) oxotechnetate. The bifunctional N-hydroxysuccinimidyl ester of mercaptoacetyltriglycine with S-acetyl protection of the sulfhydryl group may be used to conjugate MAG3 to primary amine functionalized biomolecules for the purpose of radiolabeling with 99mTc for gamma detection or single photon emission computed tomography imaging (SPECT). We report here an improved MAG3 conjugation and 99mTc radiolabeling method capable of generating high radiochemical yield and high specific radioactivity. Post-labeling purification will not be needed if the protocol is followed as presented. Apart from the preparation of reagents, the conjugation and purification requires about 4 h, while the labeling with 99mTc requires about an additional 30 min.

  16. Distribution of radiolabeled endotoxin with particular reference to the eye: concise communication.

    PubMed

    Rosenbaum, J T; Hendricks, P A; Shively, J E; McDougall, I R

    1983-01-01

    A single systemic injection of endotoxin (lipopolysaccharide or LPS) reproducibly induces a cellular infiltrate in the uveal tract of the rat eye within 24 hr. Other organs are not comparably sensitive to systemic endotoxin. One hypothesis to explain this unique sensitivity is that endotoxin is preferentially bound by ocular tissue. We tested this hypothesis by studying the distribution in the rat of intravenously injected endotoxin that had been radiolabeled with Tc-99m or P-32. With either radionuclide the concentration of endotoxin per gram of tissue at a variety of times after injection ranging from 5 min to 3 hr and 45 min, was markedly less in the eye than in liver, kidney, or spleen. A study with radiolabeled albumin indicated that these differences could not be ascribed solely to the organ's blood volume. They demonstrate, therefore, that the eye does not preferentially bind endotoxin, and they are compatible with the hypothesis that endotoxin's ocular effects are indirectly mediated.

  17. Distribution of radiolabeled endotoxin with particular reference to the eye: concise communication

    SciTech Connect

    Rosenbaum, J.T.; Hendricks, P.A.; Shively, J.E.; McDougall, I.R.

    1983-01-01

    A single systemic injection of endotoxin (lipopolysaccharide or LPS) reproducibly induces a cellular infiltrate in the uveal tract of the rat eye within 24 hr. Other organs are not comparably sensitive to systemic endotoxin. One hypothesis to explain this unique sensitivity is that endotoxin is preferentially bound by ocular tissue. Researchers tested this hypothesis by studying the distribution in the rat of intravenously injected endotoxin that had been radiolabeled with /sup 99m/Tc or /sup 32/P. With either radionuclide the concentration of endotoxin per gram of tissue at a variety of times after injection ranging from 5 min to 3 hr and 45 min, was markedly less in the eye than in liver, kidney, or spleen. A study with radiolabeled albumin indicated that these differences could not be ascribed solely to the organ's blood volume. They demonstrate, therefore, that the eye does not preferentially bind endotoxin, and they are compatible with the hypothesis that endotoxin's ocular effects are indirectly mediated.

  18. Preparation and biodistribution of 59Fe-radiolabelled iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pospisilova, Martina; Zapotocky, Vojtech; Nesporova, Kristina; Laznicek, Milan; Laznickova, Alice; Zidek, Ondrej; Cepa, Martin; Vagnerova, Hana; Velebny, Vladimir

    2017-02-01

    We report on the 59Fe radiolabelling of iron oxide nanoparticle cores through post-synthetic isotope exchange (59Fe-IONPex) and precursor labelling (59Fe-IONPpre). Scanning electron microscopy and dynamic light scattering measurements showed no impact of radiolabelling on nanoparticle size or morphology. While incorporation efficiencies of these methods are comparable—83 and 90% for precursor labelling and post-synthetic isotope exchange, respectively—59Fe-IONPpre exhibited much higher radiochemical stability in citrated human plasma. Quantitative ex vivo biodistribution study of 59Fe-IONPpre coated with triethylene glycol was performed in Wistar rats. Following the intravenous administration, high 59Fe concentration was observed in the lung and the organs of the reticuloendothelial system such as the liver, the spleen and the femur.

  19. Technical Report (Final): Development of Solid State Reagents for Preparing Radiolabeled Imaging Agents

    SciTech Connect

    Kabalka, George W

    2011-05-20

    The goal of this research was on the development of new, rapid, and efficient synthetic methods for incorporating short-lived radionuclides into agents of use in measuring dynamic processes. The initial project period (Year 1) was focused on the preparation of stable, solid state precursors that could be used to efficiently incorporate short-lived radioisotopes into small molecules of use in biological applications (environmental, plant, and animal). The investigation included development and evaluation of new methods for preparing carbon-carbon and carbon-halogen bonds for use in constructing the substrates to be radiolabeled. The second phase (Year 2) was focused on developing isotope incorporation techniques using the stable, boronated polymeric precursors. The final phase (Year 3), was focused on the preparation of specific radiolabeled agents and evaluation of their biodistribution using micro-PET and micro-SPECT. In addition, we began the development of a new series of polymeric borane reagents based on polyethylene glycol backbones.

  20. Multiplex Sequential Immunoprecipitation of Insulin Secretory Granule Proteins from Radiolabeled Pancreatic Islets.

    PubMed

    Guest, Paul C

    2017-01-01

    Pulse radiolabeling of cells with radioactive amino acids is a common method for tracking the biosynthesis of proteins. Specific proteins can then be immunoprecipitated and analyzed by electrophoresis and imaging techniques. This chapter presents a protocol for the biosynthetic labeling of pancreatic islets with (35)S-methionine, followed by multiplex sequential immunoprecipitation of insulin and three other secretory granule accessory proteins. This provided a means of distinguishing those pancreatic islet proteins with different biosynthetic rates in response to the media glucose concentrations.

  1. Imaging necrotic myocardium: Detection with 99mTc-pyrophosphate and radiolabeled antimyosin

    SciTech Connect

    Khaw, B.A.; Haber, E. )

    1989-08-01

    The major value of hot-spot imaging of the myocardium is its ability to define areas of necrosis rather than areas of diminished blood flow or cellular function. Applications of hot-spot imaging include the diagnosis and quantitation of myocardial infarction, myocarditis, and cardiac transplant rejection. The two agents in clinical use, 99mTc-Pyrophosphate and radiolabeled antimyosin, are discussed. 52 references.

  2. Clickable, hydrophilic ligand for fac-[M(I)(CO)3](+) (M = Re/(99m)Tc) applied in an S-functionalized α-MSH peptide.

    PubMed

    Kasten, Benjamin B; Ma, Xiaowei; Liu, Hongguang; Hayes, Thomas R; Barnes, Charles L; Qi, Shibo; Cheng, Kai; Bottorff, Shalina C; Slocumb, Winston S; Wang, Jing; Cheng, Zhen; Benny, Paul D

    2014-03-19

    The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction was used to incorporate alkyne-functionalized dipicolylamine (DPA) ligands (1 and 3) for fac-[M(I)(CO)3](+) (M = Re/(99m)Tc) complexation into an α-melanocyte stimulating hormone (α-MSH) peptide analogue. A novel DPA ligand with carboxylate substitutions on the pyridyl rings (3) was designed to increase the hydrophilicity and to decrease in vivo hepatobiliary retention of fac-[(99m)Tc(I)(CO)3](+) complexes used in single photon emission computed tomography (SPECT) imaging studies with targeting biomolecules. The fac-[Re(I)(CO)3(3)] complex (4) was used for chemical characterization and X-ray crystal analysis prior to radiolabeling studies between 3 and fac-[(99m)Tc(I)(OH2)3(CO)3](+). The corresponding (99m)Tc complex (4a) was obtained in high radiochemical yields, was stable in vitro for 24 h during amino acid challenge and serum stability assays, and showed increased hydrophilicity by log P analysis compared to an analogous complex with nonfunctionalized pyridine rings (2a). An α-MSH peptide functionalized with an azide was labeled with fac-[M(I)(CO)3](+) using both click, then chelate (CuAAC reaction with 1 or 3 followed by metal complexation) and chelate, then click (metal complexation of 1 and 3 followed by CuAAC with the peptide) strategies to assess the effects of CuAAC conditions on fac-[M(I)(CO)3](+) complexation within a peptide framework. The peptides from the click, then chelate strategy had different HPLC tR's and in vitro stabilities compared to those from the chelate, then click strategy, suggesting nonspecific coordination of fac-[M(I)(CO)3](+) using this synthetic route. The fac-[M(I)(CO)3](+)-complexed peptides from the chelate, then click strategy showed >90% stability during in vitro challenge conditions for 6 h, demonstrated high affinity and specificity for the melanocortin 1 receptor (MC1R) in IC50 analyses, and led to moderately high uptake in B16F10 melanoma cells

  3. Recombinant canine single chain insulin analogues: insulin receptor binding capacity and ability to stimulate glucose uptake.

    PubMed

    Adams, Jamie P; Holder, Angela L; Catchpole, Brian

    2014-12-01

    Virtually all diabetic dogs require exogenous insulin therapy to control their hyperglycaemia. In the UK, the only licensed insulin product currently available is a purified porcine insulin preparation. Recombinant insulin is somewhat problematic in terms of its manufacture, since the gene product (preproinsulin) undergoes substantial post-translational modification in pancreatic β cells before it becomes biologically active. The aim of the present study was to develop recombinant canine single chain insulin (SCI) analogues that could be produced in a prokaryotic expression system and which would require minimal processing. Three recombinant SCI constructs were developed in a prokaryotic expression vector, by replacing the insulin C-peptide sequence with one encoding a synthetic peptide (GGGPGKR), or with one of two insulin-like growth factor (IGF)-2 C-peptide coding sequences (human: SRVSRRSR; canine: SRVTRRSSR). Recombinant proteins were expressed in the periplasmic fraction of Escherichia coli and assessed for their ability to bind to the insulin and IGF-1 receptors, and to stimulate glucose uptake in 3T3-L1 adipocytes. All three recombinant SCI analogues demonstrated preferential binding to the insulin receptor compared to the IGF-1 receptor, with increased binding compared to recombinant canine proinsulin. The recombinant SCI analogues stimulated glucose uptake in 3T3-L1 adipocytes compared to negligible uptake using recombinant canine proinsulin, with the canine insulin/cIGF-2 chimaeric SCI analogue demonstrating the greatest effect. Thus, biologically-active recombinant canine SCI analogues can be produced relatively easily in bacteria, which could potentially be used for treatment of diabetic dogs.

  4. Antimicrobial Peptides

    PubMed Central

    Bahar, Ali Adem; Ren, Dacheng

    2013-01-01

    The rapid increase in drug-resistant infections has presented a serious challenge to antimicrobial therapies. The failure of the most potent antibiotics to kill “superbugs” emphasizes the urgent need to develop other control agents. Here we review the history and new development of antimicrobial peptides (AMPs), a growing class of natural and synthetic peptides with a wide spectrum of targets including viruses, bacteria, fungi, and parasites. We summarize the major types of AMPs, their modes of action, and the common mechanisms of AMP resistance. In addition, we discuss the principles for designing effective AMPs and the potential of using AMPs to control biofilms (multicellular structures of bacteria embedded in extracellular matrixes) and persister cells (dormant phenotypic variants of bacterial cells that are highly tolerant to antibiotics). PMID:24287494

  5. Dual radiolabeling as a technique to track nanocarriers: the case of gold nanoparticles.

    PubMed

    Rambanapasi, Clinton; Barnard, Nicola; Grobler, Anne; Buntting, Hylton; Sonopo, Molahlehi; Jansen, David; Jordaan, Anine; Steyn, Hendrik; Zeevaart, Jan Rijn

    2015-07-16

    Gold nanoparticles (AuNPs) have shown great potential for use in nanomedicine and nanotechnologies due to their ease of synthesis and functionalization. However, their apparent biocompatibility and biodistribution is still a matter of intense debate due to the lack of clear safety data. To investigate the biodistribution of AuNPs, monodisperse 14-nm dual-radiolabeled [14C]citrate-coated [198Au]AuNPs were synthesized and their physico-chemical characteristics compared to those of non-radiolabeled AuNPs synthesized by the same method. The dual-radiolabeled AuNPs were administered to rats by oral or intravenous routes. After 24 h, the amounts of Au core and citrate surface coating were quantified using gamma spectroscopy for 198Au and liquid scintillation for the 14C. The Au core and citrate surface coating had different biodistribution profiles in the organs/tissues analyzed, and no oral absorption was observed. We conclude that the different components of the AuNPs system, in this case the Au core and citrate surface coating, did not remain intact, resulting in the different distribution profiles observed. A better understanding of the biodistribution profiles of other surface attachments or cargo of AuNPs in relation to the Au core is required to successfully use AuNPs as drug delivery vehicles.

  6. Non-opioid actions of opioid peptides.

    PubMed

    Wollemann, Mária; Benyhe, Sándor

    2004-06-04

    Beside the well known actions of opioid peptides on mu-, delta- and kappa-opioid receptors, increasing amount of pharmacological and biochemical evidence has recently been published about non-opioid actions of various opioid peptides. These effects are not abolished by naloxone treatments. Such non-opioid effects are observed both in nervous tissues and in the cellular elements of the immune system. Peptides exhibiting non-opioid effects include beta-endorphin, dynorphin A, nociceptin/OFQ, endomorphins, hemorphins and a number of Proenkephalin A derived peptides, such as Met-enkephalin, Met-enkephalin-Arg-Phe (MERF) and bovine adrenal medullary peptide (BAM22). Non-opioid actions are exerted through different neuronal receptors, e.g., dynorphin hyperalgesia through NMDA receptor, Met-enkephalin induced regulation of cell growth through zeta receptors, pain modulation by nociceptin through ORL-1 or NOP receptors, while BAM22 acts through sensory neuron specific G protein-coupled receptors (SNSR). We have investigated Met-enkephalin-Arg-Phe (MERF) and its analogues by the means of direct and indirect radioligand binding assays. It has been found that in addition to kappa(2) and delta-opioid receptors, MERF can act also through sigma(2)- or probably via FMRF-NH(2) receptors in rat cerebellum. A role of functionally assembling heterodimer receptors in mediating the non-conventional actions of these peptide ligands can not be excluded as well.

  7. Ecstasy analogues found in cacti.

    PubMed

    Bruhn, Jan G; El-Seedi, Hesham R; Stephanson, Nikolai; Beck, Olof; Shulgin, Alexander T

    2008-06-01

    Human interest in psychoactive phenethylamines is known from the use of mescaline-containing cacti and designer drugs such as Ecstasy. From the alkaloid composition of cacti we hypothesized that substances resembling Ecstasy might occur naturally. In this article we show that lophophine, homopiperonylamine and lobivine are new minor constituents of two cactus species, Lophophora williamsii (peyote) and Trichocereus pachanoi (San Pedro). This is the first report of putatively psychoactive phenethylamines besides mescaline in these cacti. A search for further biosynthetic analogues may provide new insights into the structure-activity relationships of mescaline. An intriguing question is whether the new natural compounds can be called "designer drugs."

  8. FUNCTION GENERATOR FOR ANALOGUE COMPUTERS

    DOEpatents

    Skramstad, H.K.; Wright, J.H.; Taback, L.

    1961-12-12

    An improved analogue computer is designed which can be used to determine the final ground position of radioactive fallout particles in an atomic cloud. The computer determines the fallout pattern on the basis of known wind velocity and direction at various altitudes, and intensity of radioactivity in the mushroom cloud as a function of particle size and initial height in the cloud. The output is then displayed on a cathode-ray tube so that the average or total luminance of the tube screen at any point represents the intensity of radioactive fallout at the geographical location represented by that point. (AEC)

  9. Choline Analogues in Malaria Chemotherapy

    PubMed Central

    Peyrottes, Suzanne; Caldarelli, Sergio; Wein, Sharon; Périgaud, Christian; Pellet, Alain; Vial, Henri

    2012-01-01

    Emerging resistance against well-established anti-malaria drugs warrants the introduction of new therapeutic agents with original mechanisms of action. Inhibition of membrane-based phospholipid biosynthesis, which is crucial for the parasite, has thus been proposed as a novel and promising therapeutic strategy. This review compiles literature concerning the design and study of choline analogues and related cation derivatives as potential anti-malarials. It covers advances achieved over the last two decades and describes: the concept validation, the design and selection of a clinical candidate (Albitiazolium), back-up derivatives while also providing insight into the development of prodrug approaches. PMID:22607139

  10. Long-acting lipidated analogue of human pancreatic polypeptide is slowly released into circulation.

    PubMed

    Bellmann-Sickert, Kathrin; Elling, Christian E; Madsen, Andreas N; Little, Paul B; Lundgren, Karsten; Gerlach, Lars-Ole; Bergmann, Ralf; Holst, Birgitte; Schwartz, Thue W; Beck-Sickinger, Annette G

    2011-04-28

    The main disadvantages of peptide pharmaceuticals are their rapid degradation and excretion, their low hydrophilicity, and low shelf lifes. These bottlenecks can be circumvented by acylation with fatty acids (lipidation) or polyethylene glycol (PEGylation). Here, we describe the modification of a human pancreatic polypeptide analogue specific for the human (h)Y(2) and hY(4) receptor with PEGs of different size and palmitic acid. Receptor specificity was demonstrated by competitive binding studies. Modifications had only a small influence on binding affinities and no influence on secondary structure. Both modifications improved pharmacokinetic properties of the hPP analogue in vivo and in vitro, however, lipidation showed a greater resistance to degradation and excretion than PEGylation. Furthermore, the lipidated peptide is taken up and degraded solely by the liver but not the kidneys. Lipidation resulted in prolonged action of the hPP analogue in respect of reducing food intake in mice after subcutaneous administration. Therefore, the lipidated hPP analogue could constitute a potential new therapeutic agent against obesity.

  11. Leiurotoxin I (scyllatoxin), a peptide ligand for Ca2(+)-activated K+ channels. Chemical synthesis, radiolabeling, and receptor characterization

    SciTech Connect

    Auguste, P.; Hugues, M.; Grave, B.; Gesquiere, J.C.; Maes, P.; Tartar, A.; Romey, G.; Schweitz, H.; Lazdunski, M. )

    1990-03-15

    Leiurotoxin I (scyllatoxin) is a 31-amino acid polypeptide from the venom of the scorpion Leiurus quinquestriatus hebraeus which has been previously isolated and sequenced by others. This paper reports (i) the total synthesis of this scorpion neurotoxin as well as some aspects of its structure-function relationships; (ii) the synthesis of the analog (Tyr2)leiurotoxin I (scyllatoxin) that has been monoiodinated at high specific radioactivity (2000 Ci/mmol) and has served for the characterization of the properties of {sup 125}I-(Tyr2)leiurotoxin I binding sites (Kd = 80 pM, molecular mass of 27 and 57 kDa for two polypeptides in the leiurotoxin I binding protein); (iii) the similarity of physiological actions between leiurotoxin I and apamin. Both toxins contract Taenia coli previously relaxed with epinephrine, both toxins block the after-hyperpolarization due to Ca2(+)-activated K+ channel activity in muscle cells in culture; (iv) the probable identity of binding sites for apamin and leiurotoxin I. In spite of a different chemical structure apamin competitively inhibits {sup 125}I-(Tyr2) leiurotoxin I binding and vice versa. Moreover, the peculiar effects of K+ on {sup 125}I-(Tyr2)leiurotoxin I binding are identical to those previously observed for {sup 125}I-apamin binding.

  12. Noninvasive molecular imaging of MYC mRNA expression in human breast cancer xenografts with a [99mTc]peptide-peptide nucleic acid-peptide chimera.

    PubMed

    Tian, Xiaobing; Aruva, Mohan R; Qin, Wenyi; Zhu, Weizhu; Sauter, Edward R; Thakur, Mathew L; Wickstrom, Eric

    2005-01-01

    Human estrogen receptor-positive breast cancer cells typically display elevated levels of Myc protein due to overexpression of MYC mRNA, and elevated insulin-like growth factor 1 receptor (IGF1R) due to overexpression of IGF1R mRNA. We hypothesized that scintigraphic detection of MYC peptide nucleic acid (PNA) probes with an IGF1 peptide loop on the C-terminus, and a [99mTc]chelator peptide on the N-terminus, could measure levels of MYC mRNA noninvasively in human IGF1R-overexpressing MCF7 breast cancer xenografts in nude mice. We prepared the chelator-MYC PNA-IGF1 peptide, as well as a 4-nt mismatch PNA control, by solid-phase synthesis. We imaged MCF7 xenografts scintigraphically and measured the distribution of [99mTc]probes by scintillation counting of dissected tissues. MCF7 xenografts in nude mice were visualized at 4 and 24 h after tail vein administration of the [99mTc]PNA probe specific for MYC mRNA, but not with the mismatch control. The [99mTc]probes distributed normally to the kidneys, livers, tumors, and other tissues. Molecular imaging of oncogene mRNAs in solid tumors with radiolabel-PNA-peptide chimeras might provide additional genetic characterization of preinvasive and invasive breast cancers.

  13. Review cyclic peptides on a merry-go-round; towards drug design.

    PubMed

    Tapeinou, Anthi; Matsoukas, Minos-Timotheos; Simal, Carmen; Tselios, Theodore

    2015-09-01

    Peptides and proteins are attractive initial leads for the rational design of bioactive molecules. Several natural cyclic peptides have recently emerged as templates for drug design due to their resistance to chemical or enzymatic hydrolysis and high selectivity to receptors. The development of practical protocols that mimic the power of nature's strategies remains paramount for the advancement of novel peptide-based drugs. The de novo design of peptide mimetics (nonpeptide molecules or cyclic peptides) for the synthesis of linear or cyclic peptides has enhanced the progress of therapeutics and diverse areas of science and technology. In the case of metabolically unstable peptide ligands, the rational design and synthesis of cyclic peptide analogues has turned into an alternative approach for improved biological activity.

  14. Preclinical Evidence on the Anticancer Properties of Food Peptides.

    PubMed

    Rajendran, Subin R C K; Ejike, Chukwunonso E C C; Gong, Min; Hannah, William; Udenigwe, Chibuike C

    2017-01-01

    Natural, synthetic and analogues of peptides have shown prospects for application in cancer chemotherapy. Notably, some food protein-derived peptides are known to possess anticancer activities in cultured cancer cells, and also in animal cancer models via different mechanisms including induction of apoptosis, cell cycle arrest, cellular membrane disruption, inhibition of intracellular signalling, topoisomerases and proteases, and antiangiogenic activity. Although the mechanism of several anticancer food peptides is yet to be clearly elucidated, there is potential for practical applications of the peptides as functional food and nutraceutical ingredients, especially in adjuvant cancer therapy. This review describes the aetiological mechanisms of cancers and the production, structures, mechanisms of action, availability, and cellular and physiological anticancer activities of the food peptides.

  15. Electrostatic evaluation of isosteric analogues

    NASA Astrophysics Data System (ADS)

    Sayle, Roger; Nicholls, Anthony

    2006-04-01

    A method is presented for enumerating a large number of isosteric analogues of a ligand from a known protein-ligand complex structure and then rapidly calculating an estimate of their binding energies. This approach takes full advantage of the observed crystal structure, by reusing the atomic co-ordinates determined experimentally for one ligand, to approximate those of similar compounds that have approximately the same shape. By assuming that compounds with similar shapes adopt similar binding poses, and that entropic and protein flexibility effects are approximately constant across such an isosteric series ("the frozen ligand approximation"), it is possible to order their binding affinities relatively accurately. Additionally, the constraint that the atomic coordinates are invariant allows for a dramatic simplification in the Poisson-Boltzmann method used to calculation the electrostatic component of the binding energy. This algorithmic improvement allows for the calculation of tens of thousands of binding energies per second for drug-like molecules, enabling this technique to be used in screening large virtual libraries of isosteric analogues. Most significantly, this procedure is shown to be able to reproduce SAR effects of subtle medicinal chemistry substitutions. Finally, this paper reports the results of the proposed methodology on␣seven model systems; dihydrofolate reductase, Lck␣kinase, ribosome inactivating protein, l-arabinose binding protein, neuraminidase, HIV-1 reverse transcriptase and COX-2.

  16. The Valles natural analogue project

    SciTech Connect

    Stockman, H.; Krumhansl, J.; Ho, C.; McConnell, V.

    1994-12-01

    The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a highlevel waste repository. The analogue site is located in the Valles Caldera in New Mexico, where a massive obsidian flow filled a paleocanyon in the Battleship Rock tuff. The obsidian flow provided a heat source, analogous to waste panels or an igneous intrusion in a repository, and caused evaporation and migration of water. The tuff and obsidian samples were analyzed for major and trace elements and mineralogy by INAA, XRF, X-ray diffraction; and scanning electron microscopy and electron microprobe. Samples were also analyzed for D/H and {sup 39}Ar/{sup 4O} isotopic composition. Overall,the effects of the heating event seem to have been slight and limited to the tuff nearest the contact. There is some evidence of devitrification and migration of volatiles in the tuff within 10 meters of the contact, but variations in major and trace element chemistry are small and difficult to distinguish from the natural (pre-heating) variability of the rocks.

  17. Heteroatom-Containing Porphyrin Analogues.

    PubMed

    Chatterjee, Tamal; Shetti, Vijayendra S; Sharma, Ritambhara; Ravikanth, Mangalampalli

    2017-02-22

    The heteroatom-containing porphyrin analogues or core-modified porphyrins that resulted from the replacement of one or two pyrrole rings with other five-membered heterocycles such as furan, thiophene, selenophene, tellurophene, indene, phosphole, and silole are highly promising macrocycles and exhibit quite different physicochemical properties compared to regular azaporphyrins. The properties of heteroporphyrins depend on the nature and number of different heterocycle(s) present in place of pyrrole ring(s). The heteroporphyrins provide unique and unprecedented coordination environments for metals. Unlike regular porphyrins, the monoheteroporphyrins are known to stabilize metals in unusual oxidation states such as Cu and Ni in +1 oxidation states. The diheteroporphyrins, which are neutral macrocycles without ionizable protons, also showed interesting coordination chemistry. Thus, significant progress has been made in last few decades on core-modified porphyrins in terms of their synthesis, their use in building multiporphyrin arrays for light-harvesting applications, their use as ligands to form interesting metal complexes, and also their use for several other studies. The synthetic methods available in the literature allow one to prepare mono- and diheteroporphyrins and their functionalized derivatives, which were used extensively to prepare several covalent and noncovalent heteroporphyrin-based multiporphyrin arrays. The methods are also developed to synthesize different hetero analogues of porphyrin derivatives such as heterocorroles, heterochlorins, heterocarbaporphyrinoids, heteroatom-substituted confused porphyrins, and so on. This Review summarizes the key developments that have occurred in heteroporphyrin chemistry over the last four decades.

  18. Highly potent analogues of luteinizing hormone-releasing hormone containing D-phenylalanine nitrogen mustard in position 6

    SciTech Connect

    Bajusz, S.; Janaky, T.; Csernus, V.J.; Bokser, L.; Fekete, M.; Srkalovic, G.; Redding, T.W.; Schally, A.V. )

    1989-08-01

    The nitrogen mustard derivatives of 4-phenylbutyric acid and L-phenylalanine, called chlorambucil (Chl) and melphalan (Mel), respectively, have been incorporated into several peptide hormones, including luteinizing hormone-releasing hormone (LH-RH). The alkylating analogues of LH-RH were prepared by linking Chl, as an N-acyl moiety, to the complete amino acid sequence of agonistic and antagonistic analogues. These compounds, in particular the antagonistic analogues, showed much lower potency than their congeners carrying other acyl groups. To obtain highly potent alkylating analogues of LH-RH, the D enantiomer of Mel was incorporated into position 6 of the native hormone and some of its antagonistic analogues. Of the peptides prepared, (D-Mel{sup 6})LH-RH (SB-05) and (Ac-D-Nal(2){sup 1},D-Phe(pCl){sup 2},D-Pal(3){sup 3},Arg{sup 5},D-Mel{sup 6},D-Ala{sup 10})LH-RH (SB-86, where Nal(2) is 3-(2-naphthyl)alanine and Pal(3) is 3-(3-pyridyl)alanine) possessed the expected high agonistic and antagonistic activities, respectively, and also showed high affinities for the membrane receptors of rat pituitary cells, human breast cancer cells, human prostate cancer cells, and rat Dunning R-3327 prostate tumor cells. These two analogues exerted cytotoxic effects on human and rat mammary cancer cells in vitro. Thus these two D-Mel{sup 6} analogues seem to be particularly suitable for the study of how alkylating analogues of LH-RH could interfere with intracellular events in certain cancer cells.

  19. Highly potent analogues of luteinizing hormone-releasing hormone containing D-phenylalanine nitrogen mustard in position 6.

    PubMed Central

    Bajusz, S; Janaky, T; Csernus, V J; Bokser, L; Fekete, M; Srkalovic, G; Redding, T W; Schally, A V

    1989-01-01

    The nitrogen mustard derivatives of 4-phenylbutyric acid and L-phenylalanine, called chlorambucil (Chl) and melphalan (Mel), respectively, have been incorporated into several peptide hormones, including luteinizing hormone-releasing hormone (LH-RH). The alkylating analogues of LH-RH were prepared by linking Chl, as an N-acyl moiety, to the complete amino acid sequence of agonistic and antagonistic analogues. These compounds, in particular the antagonistic analogues, showed much lower potency than their congeners carrying other acyl groups. To obtain highly potent alkylating analogues of LH-RH, the D enantiomer of Mel was incorporated into position 6 of the native hormone and some of its antagonistic analogues. Of the peptides prepared, [D-Mel6]LH-RH (SB-05) and [Ac-D-Nal(2)1,D-Phe(pCl)2,D-Pal(3)3,Arg5,D-Mel6,D-Ala10++ +]LH-RH [SB-86, where Nal(2) is 3-(2-naphthyl)alanine and Pal(3) is 3-(3-pyridyl)alanine] possessed the expected high agonistic and antagonistic activities, respectively, and also showed high affinities for the membrane receptors of rat pituitary cells, human breast cancer cells, human prostate cancer cells, and rat Dunning R-3327 prostate tumor cells. These two analogues exerted cytotoxic effects on human and rat mammary cancer cells in vitro. Thus these two D-Mel6 analogues seem to be particularly suitable for the study of how alkylating analogues of LH-RH could interfere with intracellular events in certain cancer cells. PMID:2548207

  20. Fluoroolefins as peptide mimetics. 2. A computational study of the conformational ramifications of peptide bond replacement.

    PubMed

    McKinney, Brian E; Urban, Joseph J

    2010-01-21

    The design of peptide mimetic compounds is greatly facilitated by the identification of functionalities that can act as peptide replacements. The fluoroalkene moiety has recently been employed for that purpose. The purpose of this work is to examine the conformational ramifications of replacing peptide bonds with fluoroalkene moieties, thus generating peptidomimetics. The alanine dipeptide analogue (ADA) was chosen as a model compound. Three peptidomimetic systems were investigated including one generated by replacement of both peptide bonds of ADA, designated as DFA, and those generated by the single replacement of the C-terminal peptide bond and N-terminal peptide bond, designated as CFA and NFA, respectively. Conformations for all three systems were generated by exhaustive Monte Carlo searching. Relative conformational energies were calculated at the MP2/aug-cc-pVTZ/MP2/aug-cc-pVDZ (for DFA), MP2/-aug-cc-pVTZ//MP2/6-311+G(d,p), B3LYP/6-31+G(d)//B3LYP/6-31+G(d), and MMFF levels of theory. Aqueous phase conformational preferences were determined through calculations making use of continuum hydration models. The results indicate that replacement of both peptide bonds of ADA generates a peptidomimetic with conformational preferences where extended conformations are favored and the conformational profile is relatively insensitive to the nature of the surrounding medium. This is in contrast to ADA where the conformational preferences depend highly on the surrounding medium and where folded conformations with intramolecular hydrogen bonds are important in the absence of an interacting solvent. CFA and NFA are found to exhibit conformational preferences that do in some ways more closely resemble those of the alanine dipeptide analogue. This is particularly true in the case of NFA where interactions between the NH and CF groups are reminiscent of the intramolecular hydrogen bonding possible in ADA.

  1. [Chemical synthesis of lactococcin B and functional evaluation of the N-terminal domain using a truncated synthetic analogue].

    PubMed

    Lasta, S; Fajloun, Z; Mansuelle, P; Sabatier, J M; Boudabous, A; Sampieri, F

    2008-01-01

    The lactococcin B (LnB) is a hydrophobic, positively charged bacteriocin, produced by Lactococcus lactis ssp. cremoris 9B4. It consists of a peptidic chain made up of 47 amino acid residues, and inhibits Lactococcus exclusively. In order to study its biological activity a synthetic lactococcin B (LnBs) was obtained by solid-phase chemical synthesis using a Fmoc strategy. LnBs was shown to be indistinguishable from the natural peptide. In addition, a synthetic (7-47) LnBst analogue was obtained by withdrawal of peptidyl-resin after the 41 cycle of LnBs peptide chain assembly. The synthetic N-terminal truncated (7-47) LnBst analogue was found to be inactive on indicator strains. Our results strongly suggest that the first six N-terminal amino acid residues are involved in the bactericidal activity of LnB.

  2. A Thiol-Ene Coupling Approach to Native Peptide Stapling and Macrocyclization.

    PubMed

    Wang, Yuanxiang; Chou, Danny Hung-Chieh

    2015-09-07

    We report the discovery of a peptide stapling and macrocyclization method using thiol-ene reactions between two cysteine residues and an α,ω-diene in high yields. This new approach enabled us to selectively modify cysteine residues in native, unprotected peptides with a variety of stapling modifications for helix stabilization or general macrocyclization. We synthesized stapled Axin mimetic analogues and demonstrated increased alpha helicity upon peptide stapling. We then synthesized stapled p53 mimetic analogues using pure hydrocarbon linkers and demonstrated their abilities to block the p53-MDM2 interaction and selectively kill p53 wild-type colorectal carcinoma HCT-116 cells but not p53 null cells. In summary, we demonstrated a robust and versatile peptide stapling method that could be potentially applied to both synthetic and expressed peptides.

  3. Paper Synthesis, Cytotoxicity and Apoptosis Induction in Human Tumor Cells by Galaxamide and Its Analogues

    PubMed Central

    Xiao, Xi; Liao, Xiaojian; Qiu, Shaoling; Liu, Zihao; Du, Bin; Xu, Shihai

    2014-01-01

    Our previous study reported that galaxamide, which is a cyclo-pentapeptide containing five leucines that was extracted from Galaxaura filamentosa, displayed remarkable anticancer cytotoxicity. This novel cyclo-peptide provided a new skeleton for the structural modifications used in finding new drugs with better anticancer properties. In this study, five analogues were synthesized based on changing the number of d/l amino acids by adding a new amino acid, phenylalanine. Galaxamide and five of its analogues were evaluated through MTT assays to examine their cytotoxic activities. We found that modified analogue 5, which is referred to as A5, displayed broad spectrum cytotoxic activity toward every cell line tested; in addition, the IC50 of A5 was lower than that of galaxamide and the other analogues. Furthermore, we used flow cytometry and western blot assays to investigate whether galaxamide and A5 could induce cancer cell apoptosis. The flow cytometric studies showed that HepG2 cells treated with different concentrations of galaxamide or A5 over 72 h displayed significant and dose-dependent increases in the percentages of early-stage apoptotic cells. Western blotting revealed that both compounds induce caspase-dependent apoptosis in HepG2 cells through a mitochondria-mediated pathway. The results demonstrate that galaxamide and its analogues have potential applications as clinical anticancer drugs. PMID:25231922

  4. Semisynthesis and characterization of the first analogues of pro-neuropeptide y.

    PubMed

    von Eggelkraut-Gottanka, Regula; Machova, Zuzana; Grouzmann, Eric; Beck-Sickinger, Annette G

    2003-05-09

    Enzymatic cleavage of prohormone neuropeptide Y (proNPY) leads to mature neuropeptide Y (NPY), a widely distributed neuropeptide with multiple functions both peripherally and centrally. A single dibasic pair of amino acids, Lys38-Arg39, represents the recognition motif for a class of hormone-processing enzymes known as prohormone convertases (PCs). Two members of this PC family, PC1/3 and PC2, are involved in proNPY cleavage. The aim of this work was to establish an effective method for the generation of full-length 69-amino acid proNPY analogues for further studies of prohormone convertase interaction. We have chosen two ligation sites in order to perform the semisynthesis of proNPY analogues by expressed protein ligation (EPL). By using the intein-mediated purification system (IMPACT) with improved conditions for intein splicing, we were able to isolate proNPY 1-40 and proNPY 1-54 fragments as Cterminal thioesters. Peptides bearing Nterminal cysteine instead of the naturally occurring Ser41 and Thr55 residues, respectively, were generated by solid-phase peptide synthesis. Moreover, labels (carboxyfluorescein and biotin) were inserted into the peptide sequences. The synthesis of the [C41]proNPY 41-69 fragment, which proved to be a difficult peptide sequence, could be achieved by the incorporation of two pseudo-proline derivatives. Western blot analysis revealed that all five proNPY analogues are recognized by monoclonal antibodies directed against NPY as well as against the Cflanking peptide of NPY (CPON).

  5. Theranostic Radiopharmaceuticals Based on Gold Nanoparticles Labeled with (177)Lu and Conjugated to Peptides.

    PubMed

    Ferro-Flores, Guillermina; Ocampo-García, Blanca E; Santos-Cuevas, Clara L; de María Ramírez, Flor; Azorín-Vega, Erika P; Meléndez-Alafort, Laura

    2015-01-01

    Gold nanoparticles (AuNPs) have been proposed for a variety of medical applications such as localized heat sources for cancer treatment and drug delivery systems. The conjugation of peptides to AuNPs produces stable multimeric systems with target-specific molecular recognition. Lutetium- 177 ((177)Lu) has been successfully used in peptide radionuclide therapy. Recently, (177)Lu-AuNPs conjugated to different peptides have been proposed as a new class of theranostic radiopharmaceuticals. These radioconjugates may function simultaneously as molecular imaging agents, radiotherapy systems and thermal-ablation systems. This article covers advancements in the design, synthesis, physicochemical characterization, molecular recognition assessment and preclinical therapeutic efficacy of gold nanoparticles radiolabeled with (177)Lu and conjugated to RGD (-Arg-Gly-Asp-), Lys(3)-Bombesin and Tat(49-57) peptides.

  6. Development and Testing of a 212Pb/212Bi Peptide for Targeting Metastatic Melanoma

    SciTech Connect

    Fisher, Darrell R.

    2012-10-25

    The purpose of this project is to develop a new radiolabeled peptide for imaging and treating metastatic melanoma. The immunoconjugate consists of a receptor-specific peptide that targets melanoma cells. The beta-emitter lead-212 (half-life = 10.4 hours) is linked by coordination chemistry to the peptide. After injection, the peptide targets melanoma receptors on the surfaces of melanoma cells. Lead-212 decays to the alpha-emitter bismuth-212 (half-life = 60 minutes). Alpha-particles that hit melanoma cell nuclei are likely to kill the melanoma cell. For cancer cell imaging, the lead-212 is replaced by lead-203 (half-life = 52 hours). Lead-203 emits 279 keV photons (80.1% abundance) that can be imaged and measured for biodistribution analysis, cancer imaging, and quantitative dosimetry.

  7. CO2 Capture with Enzyme Synthetic Analogue

    SciTech Connect

    Cordatos, Harry

    2010-11-08

    Overview of an ongoing, 2 year research project partially funded by APRA-E to create a novel, synthetic analogue of carbonic anhydrase and incorporate it into a membrane for removal of CO2 from flue gas in coal power plants. Mechanism background, preliminary feasibility study results, molecular modeling of analogue-CO2 interaction, and program timeline are provided.

  8. Macrolactam analogues of macrolide natural products.

    PubMed

    Hügel, Helmut M; Smith, Andrew T; Rizzacasa, Mark A

    2016-12-07

    The chemical modification of macrolide natural products into aza- or lactam analogues is a strategy employed to improve their metabolic stability and biological activity. The methods for the synthesis of several lactam analogues of macrolide natural products are highlighted and aspects of their biological properties presented.

  9. C-Peptide Test

    MedlinePlus

    ... vital for the body to use its main energy source, glucose . Since C-peptide and insulin are produced ... these cases, C-peptide measurement is a useful alternative to testing for insulin. C-peptide measurements can ...

  10. Cyclic cholecystokinin analogues with high selectivity for central receptors.

    PubMed Central

    Charpentier, B; Pelaprat, D; Durieux, C; Dor, A; Reibaud, M; Blanchard, J C; Roques, B P

    1988-01-01

    Taking as a model the N-terminal folding of the cholecystokinin tyrosine-sulfated octapeptide [CCK-8; Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2] deduced from conformational studies, two cyclic cholecystokinin (CCK) analogues were synthesized by conventional peptide synthesis: Boc-D-Asp-Tyr(SO3H)-Ahx-D-Lys-Trp-Ahx-Asp-Phe-NH2 [compound I (Ahx, 2-aminohexanoic acid)] and Boc-gamma-D-Glu-Tyr(SO3H)-Ahx-D-Lys-Trp-Ahx-Asp-Phe-NH2 (compound II). The binding characteristics of these peptides were investigated on brain cortex membranes and pancreatic acini of guinea pig. Compounds I and II were competitive inhibitors of [3H]Boc[Ahx28,31]CCK-(27-33) binding to central CCK receptors and showed a high degree of selectivity for these binding sites (compound I: Ki for pancreas/Ki for brain, 179; compound II: Ki for pancreas/Ki for brain, 1979). This high selectivity was associated with a high affinity for central CCK receptors (compound I: Ki, 5.1 nM; compound II: Ki, 0.49 nM). Similar affinities and selectivities were found when 125I Bolton-Hunter-labeled CCK-8 was used as a ligand. Moreover, these compounds were only weakly active in the stimulation of amylase release from guinea pig pancreatic acini (EC50 greater than 10,000 nM) and were unable to induce contractions in the guinea pig ileum (to 10(-6) M). The two cyclic CCK analogues, therefore, appear to be synthetic ligands exhibiting both high affinity and high selectivity for central CCK binding sites. These compounds could help clarify the respective role of central and peripheral receptors for various CCK-8-induced pharmacological effects. PMID:3162318

  11. Continuous analogues of matrix factorizations

    PubMed Central

    Townsend, Alex; Trefethen, Lloyd N.

    2015-01-01

    Analogues of singular value decomposition (SVD), QR, LU and Cholesky factorizations are presented for problems in which the usual discrete matrix is replaced by a ‘quasimatrix’, continuous in one dimension, or a ‘cmatrix’, continuous in both dimensions. Two challenges arise: the generalization of the notions of triangular structure and row and column pivoting to continuous variables (required in all cases except the SVD, and far from obvious), and the convergence of the infinite series that define the cmatrix factorizations. Our generalizations of triangularity and pivoting are based on a new notion of a ‘triangular quasimatrix’. Concerning convergence of the series, we prove theorems asserting convergence provided the functions involved are sufficiently smooth. PMID:25568618

  12. Fully analogue photonic reservoir computer.

    PubMed

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-03-03

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers.

  13. Fully analogue photonic reservoir computer

    PubMed Central

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-01-01

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers. PMID:26935166

  14. [Use of somatostatin analogue for intestinal and pancreatic fistulas].

    PubMed

    Paran, H; Neufeld, D; Epstein, T; Bendahan, J; Freund, U

    1991-02-15

    The hormone somatostatin, a tetra-deca-peptide, was discovered in 1972. It inhibits the central nervous system and the endocrine and exocrine secretions of the gastrointestinal tract. The first clinical use of the hormone was to inhibit hormone-secreting tumors of the CNS. It has also been used to treat hormone-secreting tumors of the pancreas and GI tract. Treatment of small bowel and pancreatic fistulas has also been attempted. A new synthetic analogue of the hormone, SMS 210-995, (Sandostatin) has a long half-life and is highly effective after subcutaneous injection. It was used in the treatment of 3 patients with fistulas of the small bowel and pancreas. In all impressive reduction of fistula secretion was achieved within 24 hours. In 2 there was complete, spontaneous closure of the fistula: in 1 after 10 days and in the other after 15 days of treatment. In the 3rd, there was significant reduction of fistula output. There were no side-effects except for mild pain at the injection site in 1 patient. Previous reports and our own results indicate that this somatostatin analogue may be very useful in the nonsurgical treatment of GI tract fistulas.

  15. Clinical uses of gonadotropin-releasing hormone analogues.

    PubMed Central

    Casper, R F

    1991-01-01

    Gonadotropin-releasing hormone (Gn-RH) analogues are synthetic derivatives of the native hypothalamic peptide with alterations in their chemical structure that result in changes in biologic activity. Several Gn-RH agonists are available for clinical use, and all act through the same mechanism: first to stimulate and then to inhibit gonadotropin and gonadal steroid secretion by downregulating the pituitary Gn-RN receptors. This review should provide clinicians with a working knowledge of the physiologic and pharmacokinetic features of Gn-RH agonists. Although over 2000 articles concerning Gn-RH analogues have been published I chose to review only those that were the first to report a novel clinical application. Gn-RH agonists have proved to be extremely efficacious in treating gonadal steroid-dependent problems such as endometriosis, uterine leiomyoma, precocious puberty and prostate and breast cancers, and they have resulted in very few side effects. Long-term use may, however, lead to skeletal calcium loss in women as a consequence of hypoestrogenism. Further research is needed to prevent this and maintain clinical efficacy. PMID:1986827

  16. Transmembrane movement of a water-soluble analogue of mannosylphosphoryldolichol is mediated by an endoplasmic reticulum protein

    PubMed Central

    1995-01-01

    Based on topological studies mannosylphosphoryldolichol (Man-P-Dol) is synthesized on the cytoplasmic face of the RER, but functions as a mannosyl donor in Glc3Man9GlcNAc2-P-P-dolichol biosynthesis after the mannosyl-phosphoryl headgroup diffuses transversely to the luminal compartment. The transport of mannosylphosphorylcitronellol (Man-P- Cit), a water-soluble analogue of Man-P-Dol, by microsomal vesicles from mouse liver, has been investigated as a potential experimental approach to determine if a membrane protein(s) mediates the transbilayer movement of Man-P-Dol. For these studies beta-[3H]Man-P- Cit was synthesized enzymatically with a partially purified preparation of Man-P-undecaprenol synthase from Micrococcus luteus. The uptake of the radiolabeled water-soluble analogue was found to be (a) time dependent; (b) stereoselective; (c) dependent on an intact permeability barrier; (d) saturable; (e) protease-sensitive; and (f) highest in ER- enriched vesicles relative to Golgi complex-enriched vesicles and intact mitochondria. Consistent with the involvement of a membrane protein, the analogue did not enter synthetic phosphatidylcholine- liposomes. [3H]Man-P-Cit also was not transported by human erythrocytes. These results indicate that the transport of Man-P-Cit by sealed microsomal vesicles from mouse liver is mediated by a membrane protein transport system. It is possible that the same membrane protein(s) participates in the transbilayer movement of Man-P-Dol in the ER. PMID:7622555

  17. Specificity in substrate binding by protein folding catalysts: tyrosine and tryptophan residues are the recognition motifs for the binding of peptides to the pancreas-specific protein disulfide isomerase PDIp.

    PubMed Central

    Ruddock, L. W.; Freedman, R. B.; Klappa, P.

    2000-01-01

    Using a cross-linking approach, we recently demonstrated that radiolabeled peptides or misfolded proteins specifically interact in vitro with two luminal proteins in crude extracts from pancreas microsomes. The proteins were the folding catalysts protein disulfide isomerase (PDI) and PDIp, a glycosylated, PDI-related protein, expressed exclusively in the pancreas. In this study, we explore the specificity of these proteins in binding peptides and related ligands and show that tyrosine and tryptophan residues in peptides are the recognition motifs for their binding by PDIp. This peptide-binding specificity may reflect the selectivity of PDIp in binding regions of unfolded polypeptide during catalysis of protein folding. PMID:10794419

  18. Conformational studies of immunodominant myelin basic protein 1-11 analogues using NMR and molecular modeling

    NASA Astrophysics Data System (ADS)

    Laimou, Despina; Lazoura, Eliada; Troganis, Anastassios N.; Matsoukas, Minos-Timotheos; Deraos, Spyros N.; Katsara, Maria; Matsoukas, John; Apostolopoulos, Vasso; Tselios, Theodore V.

    2011-11-01

    Τwo dimensional nuclear magnetic resonance studies complimented by molecular dynamics simulations were conducted to investigate the conformation of the immunodominant epitope of acetylated myelin basic protein residues 1-11 (Ac-MBP1-11) and its altered peptide ligands, mutated at position 4 to an alanine (Ac-MBP1-11[4A]) or a tyrosine residue (Ac-MBP1-11[4Y]). Conformational analysis of the three analogues indicated that they adopt an extended conformation in DMSO solution as no long distance NOE connectivities were observed and seem to have a similar conformation when bound to the active site of the major histocompatibility complex (MHC II). The interaction of each peptide with MHC class II I-Au was further investigated in order to explore the molecular mechanism of experimental autoimmune encephalomyelitis induction/inhibition in mice. The present findings indicate that the Gln3 residue, which serves as a T-cell receptor (TCR) contact site in the TCR/peptide/I-Au complex, has a different orientation in the mutated analogues especially in the Ac-MBP1-11[4A] peptide. In particular the side chain of Gln3 is not solvent exposed as for the native Ac-MBP1-11 and it is not available for interaction with the TCR.

  19. Conformational studies of immunodominant myelin basic protein 1-11 analogues using NMR and molecular modeling.

    PubMed

    Laimou, Despina; Lazoura, Eliada; Troganis, Anastassios N; Matsoukas, Minos-Timotheos; Deraos, Spyros N; Katsara, Maria; Matsoukas, John; Apostolopoulos, Vasso; Tselios, Theodore V

    2011-11-01

    Τwo dimensional nuclear magnetic resonance studies complimented by molecular dynamics simulations were conducted to investigate the conformation of the immunodominant epitope of acetylated myelin basic protein residues 1-11 (Ac-MBP(1-11)) and its altered peptide ligands, mutated at position 4 to an alanine (Ac-MBP(1-11)[4A]) or a tyrosine residue (Ac-MBP(1-11)[4Y]). Conformational analysis of the three analogues indicated that they adopt an extended conformation in DMSO solution as no long distance NOE connectivities were observed and seem to have a similar conformation when bound to the active site of the major histocompatibility complex (MHC II). The interaction of each peptide with MHC class II I-A(u) was further investigated in order to explore the molecular mechanism of experimental autoimmune encephalomyelitis induction/inhibition in mice. The present findings indicate that the Gln(3) residue, which serves as a T-cell receptor (TCR) contact site in the TCR/peptide/I-A(u) complex, has a different orientation in the mutated analogues especially in the Ac-MBP(1-11)[4A] peptide. In particular the side chain of Gln(3) is not solvent exposed as for the native Ac-MBP(1-11) and it is not available for interaction with the TCR.

  20. Peptide and non-peptide opioid-induced hyperthermia in rabbits

    NASA Technical Reports Server (NTRS)

    Kandasamy, S. B.; Williams, B. A.

    1983-01-01

    The intracerebroventricular administration of prototype nonpeptide opioid receptor (mu, kappa, and sigma) agonists, morphine, ketocyclazocine, and N-allyl-normetazocine was found to induce hyperthermia in rabbits. The similar administration of peptide opioids like beta-endorphin (BE), methionine-enkephalin (ME), and its synthetic analogue D-ala2-methionine-enkephalinamide (DAME) was also found to cause hyperthermia. Results indicate that only the liver-like transport system is important to the ventricular inactivation of BE and DAME. Prostaglandins and norepinephrine were determined not to be involved in peptide and nonpeptide opioid-induced hyperthermia. In addition, cAMP was not required since a phosphodiesterase inhibitor, theophylline, did not accentuate the hyperthermia due to peptide and nonpeptide opioids. Naloxone-sensitive receptors were found to be involved in the induction of hyperthermia by morphine, BE, ME, and DAME since naloxone attenuated them. However, the hyperthermic response to ketocyclazocine and N-allyl-normetazocine was not antagonized by naloxone.

  1. Preparation of o-fluorophenols from nonaromatic precursors: Mechanistic considerations for adaptation to fluorine-18 radiolabeling

    DOE PAGES

    Yasui, Norio; Mayne, Christopher G.; Katzenellenbogen, John A.

    2015-11-04

    The preparation of fluorine-18 labeled o-fluorophenols at high specific activity is challenging and requires use of [18F]fluoride ion as the radioisotope source. As a novel, alternative approach, in this study we found that treatment of α-diazocyclohexenones with Selectfluor and Et3N·3HF followed by HF elimination and tautomerization afforded o-fluorophenols regioselectively and rapidly. Finally, to adapt this chemistry to 18F radiolabeling, using bromine electrophiles in place of Selectfluor gave the o-fluorophenol via an α-bromo-α-fluoroketone intermediate in lower but still reasonable yields.

  2. Tumor localization with gallium, radiolabeled bleomycin, thallium, selenium, carbon and nitrogen radionuclides. Oncology overview

    SciTech Connect

    Not Available

    1981-07-01

    Oncology Overviews are a service of the International Cancer Research Data Bank (ICRDB) Program of the National Cancer Institute, intended to facilitate and promote the exchange of information between cancer scientists by keeping them aware of literature related to their research being published by other laboratories throughout the world. Each Oncology Overview represents a survey of the literature associated with a selected area of cancer research. It contains abstracts of articles which have been selected and organized by researchers associated with the field. Contents: Gallium scans; Radiolabeled bleomycin scans; Thallium scans; Selenium scans; Carbon radionuclide scans; Nitrogen radionuclide scans; Multiagent studies.

  3. Chelator free gallium-68 radiolabelling of silica coated iron oxide nanorods via surface interactions

    NASA Astrophysics Data System (ADS)

    Burke, Benjamin P.; Baghdadi, Neazar; Kownacka, Alicja E.; Nigam, Shubhanchi; Clemente, Gonçalo S.; Al-Yassiry, Mustafa M.; Domarkas, Juozas; Lorch, Mark; Pickles, Martin; Gibbs, Peter; Tripier, Raphaël; Cawthorne, Christopher; Archibald, Stephen J.

    2015-09-01

    The commercial availability of combined magnetic resonance imaging (MRI)/positron emission tomography (PET) scanners for clinical use has increased demand for easily prepared agents which offer signal or contrast in both modalities. Herein we describe a new class of silica coated iron-oxide nanorods (NRs) coated with polyethylene glycol (PEG) and/or a tetraazamacrocyclic chelator (DO3A). Studies of the coated NRs validate their composition and confirm their properties as in vivo T2 MRI contrast agents. Radiolabelling studies with the positron emitting radioisotope gallium-68 (t1/2 = 68 min) demonstrate that, in the presence of the silica coating, the macrocyclic chelator was not required for preparation of highly stable radiometal-NR constructs. In vivo PET-CT and MR imaging studies show the expected high liver uptake of gallium-68 radiolabelled nanorods with no significant release of gallium-68 metal ions, validating our innovation to provide a novel simple method for labelling of iron oxide NRs with a radiometal in the absence of a chelating unit that can be used for high sensitivity liver imaging.The commercial availability of combined magnetic resonance imaging (MRI)/positron emission tomography (PET) scanners for clinical use has increased demand for easily prepared agents which offer signal or contrast in both modalities. Herein we describe a new class of silica coated iron-oxide nanorods (NRs) coated with polyethylene glycol (PEG) and/or a tetraazamacrocyclic chelator (DO3A). Studies of the coated NRs validate their composition and confirm their properties as in vivo T2 MRI contrast agents. Radiolabelling studies with the positron emitting radioisotope gallium-68 (t1/2 = 68 min) demonstrate that, in the presence of the silica coating, the macrocyclic chelator was not required for preparation of highly stable radiometal-NR constructs. In vivo PET-CT and MR imaging studies show the expected high liver uptake of gallium-68 radiolabelled nanorods with no

  4. Correlating labeling chemistry and in-vitro test results with the biological behavior of radiolabeled proteins

    SciTech Connect

    Srivastava, S.C.; Meinken, G.E.

    1985-01-01

    Monoclonal antibodies possess enormous potential for delivery of therapeutic amounts of radionuclides to target antigens in vivo, in particular for tumor imaging and therapy. Translation of this concept into practice has encountered numerous problems. Specifically whereas general protein radiolabeling methods are applicable to antibodies, immunological properties of the antibodies are often compromised resulting in reduced in-vivo specificity for the target antigens. The bifunctional chelating agent approach shows the most promise, however, development of other agents will be necessary for widespread usefulness of this technique. The effects of labeling chemistry on the in-vivo behavior of several monoclonal antibodies are described. 30 refs., 4 figs., 10 tabs.

  5. Alternate radiolabeled markers for detecting metabolic activity of Mycobacterium leprae residing in murine macrophages

    SciTech Connect

    Prasad, H.K.; Hastings, R.C.

    1985-05-01

    This study demonstrated the utility of using 4% NaOH as a murine macrophage cell-solubilizing agent to discriminate between host macrophage metabolism and that of intracellular Mycobacterium leprae. A 4% concentration of NaOH had no deleterious effect on labeled mycobacteria. Thereby, alternate radiolabeled indicators of the metabolic activity of intracellular M. leprae could be experimented with. Significant incorporation of /sup 14/C-amino acid mixture, (/sup 14/C)leucine, (/sup 14/C)uridine, and carrier-free /sup 32/P was observed in cultures containing freshly extracted (''live'') strains of M. leprae as compared with control cultures containing autoclaved bacilli.

  6. Carbon-11 radiolabeling of iron-oxide nanoparticles for dual-modality PET/MR imaging

    NASA Astrophysics Data System (ADS)

    Sharma, Ramesh; Xu, Youwen; Kim, Sung Won; Schueller, Michael J.; Alexoff, David; Smith, S. David; Wang, Wei; Schlyer, David

    2013-07-01

    Dual-modality imaging, using Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) simultaneously, is a powerful tool to gain valuable information correlating structure with function in biomedicine. The advantage of this dual approach is that the strengths of one modality can balance the weaknesses of the other. However, success of this technique requires developing imaging probes suitable for both. Here, we report on the development of a nanoparticle labeling procedure via covalent bonding with carbon-11 PET isotope. Carbon-11 in the form of [11C]methyl iodide was used as a methylation agent to react with carboxylic acid (-COOH) and amine (-NH2) functional groups of ligands bound to the nanoparticles (NPs). The surface coating ligands present on superparamagnetic iron-oxide nanoparticles (SPIO NPs) were radiolabeled to achieve dual-modality PET/MR imaging capabilities. The proof-of-concept dual-modality PET/MR imaging using the radiolabeled SPIO NPs was demonstrated in an in vivo experiment.Dual-modality imaging, using Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) simultaneously, is a powerful tool to gain valuable information correlating structure with function in biomedicine. The advantage of this dual approach is that the strengths of one modality can balance the weaknesses of the other. However, success of this technique requires developing imaging probes suitable for both. Here, we report on the development of a nanoparticle labeling procedure via covalent bonding with carbon-11 PET isotope. Carbon-11 in the form of [11C]methyl iodide was used as a methylation agent to react with carboxylic acid (-COOH) and amine (-NH2) functional groups of ligands bound to the nanoparticles (NPs). The surface coating ligands present on superparamagnetic iron-oxide nanoparticles (SPIO NPs) were radiolabeled to achieve dual-modality PET/MR imaging capabilities. The proof-of-concept dual-modality PET/MR imaging using the radiolabeled

  7. Whole-body effective half-lives for radiolabeled antibodies and related issues

    SciTech Connect

    Kaurin, D.G.L.; Carsten, A.L.; Baum, J.W.; Barber, D.E.

    1996-08-01

    Radiolabeled antibodies (RABs) are being developed and used in medical imaging and therapy in rapidly increasing numbers. Data on the whole body half effective half-lives were calculated from external dose rates obtained from attending physicians and radiation safety officers at participating institutions. Calculations were made using exponential regression analysis of data from patients receiving single and multiple administrations. Theses data were analyzed on the basis of age, sex, isotope label, radiation energy, antibody type, disease treated, administration method, and number of administrations.

  8. Radiolabeled iron in soybeans: intrinsic labeling and bioavailability of iron to rats from defatted flour

    SciTech Connect

    Weaver, C.M.; Schmitt, H.A.; Stuart, M.A.; Mason, A.C.; Meyer, N.R.; Elliott, J.G.

    1984-06-01

    Soybeans can be efficiently labeled with radiolabeled iron by supplying the iron via a nutrient culture medium as an iron salt or as a chelate. By using dual labeled iron and EDTA, it was determined that none of the chelator was transported to the shoots with the iron. Therefore, the use of chelated iron as the iron source in the nutrient medium should not affect assessments of bioavailability of iron from plants. Bioavailability (determined from whole-body retention curves of /sup 59/Fe in rats) of iron from defatted soy flour was relatively high and addition of vitamin C did not significantly enhance absorption of iron from defatted soy flour.

  9. Ribosomal synthesis of dehydroalanine-containing peptides.

    PubMed

    Seebeck, Florian P; Szostak, Jack W

    2006-06-07

    Dehydroalanine is a nonproteinogenic amino acid, but it is a component of a wide variety of natural products with therapeutic activities. Indeed, this alpha,beta-unsaturated residue is a highly versatile building block due to its rigidifying effect on peptide backbones and its electrophilicity which allows site-specific thiol ligations of peptides with small molecules or proteins. To harness such versatility in genetically encoded, combinatorial peptide libraries, we report a simple and robust method for the ribosomal synthesis of dehydroalanine-containing peptides. Selenalysine, a selenium-containing lysine analogue, was recruited as a masked dehydroalanine equivalent. This residue is efficiently incorporated by a reconstituted Escherichia coli translation system at high fidelity and efficiency despite the presence of low levels of lysine. Mild oxidative conditions were used to convert selenalysine into dehydroalanine post-translationally. Using this method, we demonstrate the preparation of polyunsaturated and highly decorated peptides. This report is an important step toward the preparation and selection of large libraries of protein-reactive compounds with potential use as novel drugs or as analytical tools.

  10. In Vivo Efficacy of Anuran Trypsin Inhibitory Peptides against Staphylococcal Skin Infection and the Impact of Peptide Cyclization

    PubMed Central

    Malik, U.; Silva, O. N.; Fensterseifer, I. C. M.; Chan, L. Y.; Clark, R. J.; Franco, O. L.; Daly, N. L.

    2015-01-01

    Staphylococcus aureus is a virulent pathogen that is responsible for a wide range of superficial and invasive infections. Its resistance to existing antimicrobial drugs is a global problem, and the development of novel antimicrobial agents is crucial. Antimicrobial peptides from natural resources offer potential as new treatments against staphylococcal infections. In the current study, we have examined the antimicrobial properties of peptides isolated from anuran skin secretions and cyclized synthetic analogues of these peptides. The structures of the peptides were elucidated by nuclear magnetic resonance (NMR) spectroscopy, revealing high structural and sequence similarity with each other and with sunflower trypsin inhibitor 1 (SFTI-1). SFTI-1 is an ultrastable cyclic peptide isolated from sunflower seeds that has subnanomolar trypsin inhibitory activity, and this scaffold offers pharmaceutically relevant characteristics. The five anuran peptides were nonhemolytic and noncytotoxic and had trypsin inhibitory activities similar to that of SFTI-1. They demonstrated weak in vitro inhibitory activities against S. aureus, but several had strong antibacterial activities against S. aureus in an in vivo murine wound infection model. pYR, an immunomodulatory peptide from Rana sevosa, was the most potent, with complete bacterial clearance at 3 mg · kg−1. Cyclization of the peptides improved their stability but was associated with a concomitant decrease in antimicrobial activity. In summary, these anuran peptides are promising as novel therapeutic agents for treating infections from a clinically resistant pathogen. PMID:25624332

  11. Synthesis and evaluation of analogues of HYNIC as bifunctional chelators for technetium.

    PubMed

    Meszaros, Levente K; Dose, Anica; Biagini, Stefano C G; Blower, Philip J

    2011-06-21

    6-Hydrazinonicotinic acid (HYNIC, 1) is a well-established bifunctional technetium-binding ligand often used to synthesise bioconjugates for radiolabelling with Tc-99m. It is capable of efficient capture of technetium at extremely low concentrations, but the structure of the labelled complexes is heterogeneous and incompletely understood. In particular, it is of interest to determine whether, at the no-carrier-added level, it acts in a chelating or non-chelating mode. Here we report two new isomers of HYNIC: 2-hydrazinonicotinic acid (2-HYNIC, 2), which (like 1) is capable of chelation through the mutually ortho hydrazine and pyridine nitrogens and 4-hydrazinonicotinic acid (4-HYNIC, 3), which is not (due to the para-relationship of the hydrazine and pyridine nitrogens). LC-MS shows that the coordination chemistry of 2 with technetium closely parallels that of conventional 1, and no advantages of one over the other in terms of potential labelling efficiency or isomerism were discernable. Both 1 and 2 formed complexes with the loss of 5 protons from the ligand set, whether the co-ligand was tricine or EDDA. Ligand 3, however, failed to complex technetium except at very high ligand concentration: the marked contrast with 1 and 2 suggests that chelation, rather than nonchelating coordination, is a key feature of technetium coordination by HYNIC. Two further new HYNIC analogues, 2-chloro-6-hydrazinonicotinic acid (2-chloro-HYNIC, 4a) and 2,6-dihydrazinonicotinic acid (diHYNIC, 5) were also synthesised. The coordination chemistry of 4a with technetium was broadly parallel to that of 1 and 2 although it was a less efficient chelator, while 5 also behaved as an efficient chelator of technetium, but its coordination chemistry remains poorly defined and requires further investigation before it can sensibly be adopted for (99m)Tc-labelling. The new analogues 4a and 5 present an opportunity to develop trifunctional HYNIC analogues for more complex bioconjugate synthesis.

  12. New strategy for the preparation of clickable peptides and labeling with 1-(azidomethyl)-4-[(18)F]-fluorobenzene for PET.

    PubMed

    Thonon, David; Kech, Cécile; Paris, Jérôme; Lemaire, Christian; Luxen, André

    2009-04-01

    The alkyne-azide Cu(I)-catalyzed Huisgen cycloaddition, a click type reaction was used to label a peptide with fluorine-18. A novel solid phase synthesis approach for the preparation of clickable peptides has been developed and has also permitted the straightforward preparation of reference compounds. A complementary azide labeling agent (1-(azidomethyl)-4-[(18)F]-fluorobenzene) has been produced in a four step procedure in 75 min with a 34% radiochemical yield (decay corrected). Conjugation of [(18)F]fluoroazide with a model alkyne-neuropeptide produced the desired (18)F-radiolabeled peptide in less than 15 min with a yield of 90% and excellent radiochemical purity.

  13. Synthesis and evaluation of bombesin derivatives on the basis of pan-bombesin peptides labeled with indium-111, lutetium-177, and yttrium-90 for targeting bombesin receptor-expressing tumors.

    PubMed

    Zhang, Hanwen; Chen, Jianhua; Waldherr, Christian; Hinni, Karin; Waser, Beatrice; Reubi, Jean Claude; Maecke, Helmut R

    2004-09-15

    Bombesin receptors are overexpressed on a variety of human tumors like prostate, breast, and lung cancer. The aim of this study was to develop radiolabeled (Indium-111, Lutetium-177, and Yttrium-90) bombesin analogues with affinity to the three bombesin receptor subtypes for targeted radiotherapy. The following structures were synthesized: diethylenetriaminepentaacetic acid-gamma-aminobutyric acid-[D-Tyr6, beta-Ala11, Thi13, Nle14] bombesin (6-14) (BZH1) and 1,4,7,10-tetraazacyclododecane-N,N',N",N"' -tetraacetic acid-gamma-aminobutyric acid-[D-Tyr6, beta-Ala11, Thi13, Nle14] bombesin (6-14) (BZH2). [111In]-BZH1 and in particular [90Y]-BZH2 were shown to have high affinity to all three human bombesin receptor subtypes with binding affinities in the nanomolar range. In human serum metabolic cleavage was found between beta-Ala11 and His12 with an approximate half-life of 2 hours. The metabolic breakdown was inhibited by EDTA and beta-Ala11-His12 (carnosine) indicating that carnosinase is the active enzyme. Both 111In-labeled peptides were shown to internalize into gastrin-releasing peptide-receptor-positive AR4-2J and PC-3 cells with similar high rates, which were independent of the radiometal. The biodistribution studies of [111In]-BZH1 and [111In]-BZH2 ([177Lu]-BZH2) in AR4-2J tumor-bearing rats showed specific and high uptake in gastrin-releasing peptide-receptor-positive organs and in the AR4-2J tumor. A fast clearance from blood and all of the nontarget organs except the kidneys was found. These radiopeptides were composed of the first pan-bombesin radioligands, which show great promise for the early diagnosis of tumors bearing not only gastrin-releasing peptide-receptors but also the other two bombesin receptor subtypes and may be of use in targeted radiotherapy of these tumors.

  14. Syntheses of C-peptides and human proinsulin.

    PubMed

    Yanaihara, N; Yanaihara, C; Sakagami, M; Sakura, N; Hashimoto, T; Nishida, T

    1978-01-01

    Syntheses of human, dog, rat, and duck C-peptides and their analogues and preliminary results on the total synthesis of human proinsulin are described. In the syntheses of the C-peptides, chain elongation was performed exclusively by the azide-fragment condensation method in solution. The synthetic human, dog, rat, and duck C-peptides and their analogues were proved to be homogeneous by several analytic means. With these synthetic peptides, radioimmunoassay systems for dog, rat, and duck C-peptides were developed. For the total synthesis of human proinsulin, 10 protected peptide hydrazides were prepared, and the linearly protected hexaoctacontapeptide having the proposed sequence of human proinsulin was constructed by the azide-fragment condensation method in solution starting from the C-terminal undecapeptide (HP 75-86). After deblocking of the alpha-amino protection, the partially protected hexaoctacontapeptide was treated with sodium in liquid ammonia. The ensuing sulfhydryl form was converted to the S-sulfonate form, which was reduced and then air-oxidized. The oxidized material was purified by gel filtration on Sephadex G-50 (fine) followed by ion-exchange chromatography on DEAE-cellulose. The cross-reactivity in the insulin radioimmunoassay of the ensuing product was 62.5 per cent of porcine proinsulin on a weight basis at B/Bo = 60 per cent. Acid hydrolysis and amino acid analysis of this product gave the theoretically expected ratios. In addition, this peptide, as well as the S-sulfonate form of the hexaoctacontapeptide, showed displacement curves superimposable on that of synthetic human C-peptide on an equimolar basis in the human C-peptide radioimmunoassay (antiserum 527). These results confirm the synthesis of human proinsulin.

  15. The Cooperative Behaviour of α-Helical Antimicrobial Peptides in Different Environments

    NASA Astrophysics Data System (ADS)

    Pinna, Marco; Wang, Janping; Mura, Manuela; Zhou, Yuhua; Zvelindovsky, Andrei; Dennison, Sarah; Phoenix, David

    2014-03-01

    A systematic analysis of the antimicrobial peptides (AMPs) cooperative action is performed by means of a full atomistic molecular dynamics simulation. The following peptide analogues: Aurein 2.5-COOH, Aurein 2.6-COOH and Aurein 3.1-COOH are investigated in different environments including aqueous solution, trifluoroethanol (TFE), palmitoyloleoylphosphatidylethanolamine (POPE), and palmitoyloleoylphosphatidylglycerol (POPG) lipid bilayers. Simulations conducted for monomer and trimer peptide highlight the importance of the cooperative behaviour and reveal the different mechanisms of antimicrobial peptides action in different lipid bilayers.

  16. Plant Volatile Analogues Strengthen Attractiveness to Insect

    PubMed Central

    Sun, Yufeng; Yu, Hao; Zhou, Jing-Jiang; Pickett, John A.; Wu, Kongming

    2014-01-01

    Green leaf bug Apolygus lucorum (Meyer-Dür) is one of the major pests in agriculture. Management of A. lucorum was largely achieved by using pesticides. However, the increasing population of A. lucorum since growing Bt cotton widely and the increased awareness of ecoenvironment and agricultural product safety makes their population-control very challenging. Therefore this study was conducted to explore a novel ecological approach, synthetic plant volatile analogues, to manage the pest. Here, plant volatile analogues were first designed and synthesized by combining the bioactive components of β-ionone and benzaldehyde. The stabilities of β-ionone, benzaldehyde and analogue 3 g were tested. The electroantennogram (EAG) responses of A. lucorum adult antennae to the analogues were recorded. And the behavior assay and filed experiment were also conducted. In this study, thirteen analogues were acquired. The analogue 3 g was demonstrated to be more stable than β-ionone and benzaldehyde in the environment. Many of the analogues elicited EAG responses, and the EAG response values to 3 g remained unchanged during seven-day period. 3 g was also demonstrated to be attractive to A. lucorum adults in the laboratory behavior experiment and in the field. Its attractiveness persisted longer than β-ionone and benzaldehyde. This indicated that 3 g can strengthen attractiveness to insect and has potential as an attractant. Our results suggest that synthetic plant volatile analogues can strengthen attractiveness to insect. This is the first published study about synthetic plant volatile analogues that have the potential to be used in pest control. Our results will support a new ecological approach to pest control and it will be helpful to ecoenvironment and agricultural product safety. PMID:24911460

  17. Synthesis, Radiolabeling, and In Vivo Imaging of PEGylated High-Generation Polyester Dendrimers.

    PubMed

    McNelles, Stuart A; Knight, Spencer D; Janzen, Nancy; Valliant, John F; Adronov, Alex

    2015-09-14

    A fifth generation aliphatic polyester dendrimer was functionalized with vinyl groups at the periphery and a dipicolylamine Tc(I) chelate at the core. This structure was PEGylated with three different molecular weight mPEGs (mPEG160, mPEG350, and mPEG750) using thiol-ene click chemistry. The size of the resulting macromolecules was evaluated using dynamic light scattering, and it was found that the dendrimer functionalized with mPEG750 was molecularly dispersed in water, exhibiting a hydrodynamic diameter of 9.2 ± 2.1 nm. This PEGylated dendrimer was subsequently radiolabeled using [(99m)Tc(CO)3(H2O)3](+) and purified to high (>99%) radiochemical purity. Imaging studies were initially performed on healthy rats to allow comparison to previous Tc-labeled dendrimers and then on xenograft murine tumor models, which collectively showed that the dendrimers circulated in the blood for an extended period of time (up to 24 h). Furthermore, the radiolabeled dendrimer accumulated in H520 xenograft tumors, which could be visualized by single-photon emission computed tomography (SPECT). The reported PEGylated aliphatic polyester dendrimers represent a new platform for developing tumor-targeted molecular imaging probes and therapeutics.

  18. Synthesis and investigation of anticancer potential of radiolabeled naphthalene monoimide bearing imidazolium salt.

    PubMed

    Yurt Lambrecht, Fatma; Ocakoglu, Kasim; Gokhan Colak, Suleyman; Alp Ersoz, Onur; Er, Ozge

    2017-01-09

    Imidazolium salts and derivatives have antitumor efficacy and toxic effects in different micro-organisms. In this study, an imidazolium bromide salt (NMI) was synthesized, and its antitumor potential was investigated by in vitro studies. Radiolabeling of synthesized NMI was carried out by iodogen method using (131) I radionuclide. The yield of radiolabeling was determined as 98.5 ± 0.1%. After that, cytotoxicity and intracellular uptake studies were evaluated in various cell lines. The cytotoxicity of NMI was determined as 35, 20, 10, and 1 μm for HEK-293, PC-3, CaCo-2, and MCF-7 cells, respectively. In addition, the intracellular uptake of (131) I-NMI was investigated in the cell lines, and the uptake was significantly found as 4 hr for MCF-7 and 6 hr for PC-3. In future studies, antitumor efficacy of (131) I-NMI on tumor-bearing animal model might be studied in light of these results.

  19. The intravenous distribution of a radiolabeled, potentially useful cluster ion of copper and penicillamine.

    PubMed

    Clelland, C C; Giles, K D; Farley, T D; Gee, Q; Wright, J R

    1986-01-01

    The 64Cu-radiolabeled mixed valence cluster ion of copper and penicillamine (Cu(I)8Cu(II)6Pen12Cl5-) is easily prepared and purified in a 30 minute procedure. Mice were dosed intravenously with this substance at 0.1 mg/kg, and the distribution of the isotope among organs and tissues was quantified by gamma scintillometry of the isotope's positron annihilation radiation. The largest concentration was found in urine (a 96-fold increase over whole body specific activity at 20 minutes), and this finding is consistent with the compound's inulin-like renal clearance. Isotope levels were also elevated in kidney and liver tissues (2.36-and 3.62-fold, respectively), while all other organs and tissues examined were found to be depleted of the label. A pre-injection of unlabeled cluster at 60 mg/kg effectively blocked radiolabel interaction with liver tissue. This intensely red-violet compound did not stain viable liver cells, and it was not significantly decomposed by liver homogenates over a three hour period. These results suggest cluster interaction at saturable binding sites on liver cell surfaces. The unlabeled cluster shows no indication of toxicity, and the labeled version might have biomedical applications.

  20. The use of radiolabelled milk proteins to study thermally-induced interactions in milk systems

    SciTech Connect

    Noh, B.

    1988-01-01

    Heat induced complexes between milk proteins are of considerable importance in determining the heat stability and rennin clottability of milk products. Thiol-disulfide interchange reactions have been suggested as the principal reaction mechanism for complex formation. Studies to data have not adequately established the mechanism and stoichiometry of complex formation in situ in total milk system. Tracer amounts of {sup 14}C-{beta}-lactoglobulin and {alpha}-lactalbumin were heated under various conditions. After clotting with rennet, radioactivity retained in the curd was counted to estimate extent of interaction of {beta}-lactoglobulin with casein. {sup 14}C- and {sup 3}H-Methyl labelled proteins were used for the preparation of radiolabelled artificial casein micelles. These micelles with radiolabelled whey proteins were heated and heat-induced complexes were separated on Sephacryl S-300 eluting with 6 M guanidine hydrochloride to break all non-covalent bonds. Further separation of the protein complexes was obtained using CPG-10 or Sephacryl S-1000. The ratios of {sup 3}H to {sup 14}C labelled proteins in the protein complexes suggested that the stoichiometries of k-, {alpha}{sub s2}-casein, {beta}-lactoglobulin and {alpha}-lactalbumin in the heat-induced complexes varied as a function of the heat treatment.

  1. In vitro characterization of two novel biodegradable vectors for the delivery of radiolabeled antisense oligonucleotides.

    PubMed

    von Guggenberg, Elisabeth; Shahhosseini, Soraya; Koslowsky, Ingrid; Lavasanifar, Afsaneh; Murray, David; Mercer, John

    2010-12-01

    The development of antisense oligonucleotides suitable for tumor targeting applications is hindered by low stability and bioavailability of oligonucleotides in vivo and by the absence of efficient and safe vectors for oligonucleotide delivery. Stabilization in vivo has been achieved through chemical modification of oligonucleotides by various means, but effective approaches to enhance their intracellular delivery are lacking. This study reports on the characterization in vitro of a fully phosphorothioated 20-mer oligonucleotide, complementary to p21 mRNA, radiolabeled with fluorine-18 using a thiol reactive prosthetic group. The potential of two novel synthetic block copolymers containing grafted polyamines on their hydrophobic blocks for vector-assisted cell delivery was studied in vitro. Extensive cellular uptake studies were performed in human colon carcinoma cell lines with enhanced or deficient p21 expression to evaluate and compare the uptake mechanism of naked and vectorized radiolabeled formulations. Uptake studies with the two novel biodegradable vectors showed a moderate increase in cell uptake of the radiofluorinated antisense oligonucleotide. The two vectors show, however, promising advantages over conventional lipidic vectors regarding their biocompatibility and subcellular distribution.

  2. Decaying radiolabelled lymphocytes and method of using same background of the invention

    SciTech Connect

    Chambers, G.P.

    1994-12-30

    Decaying radiolabelled lymphocytes and a method of using same are disclosed. A radiolabelled T-cell lymphocyte including a T-cell containing a Beta-emitting isotope which decays to an alpha-emitting isotope is provided. Alternatively, the T-cell may contain a Beta-emitting isotope which decays one of an x-ray and gamma-emitting isotope. A therapeutic radioisotope treatment method includes the steps of removing a cancerous nodule containing T-cells from a mammal, introducing into the T-cells a Beta-emitting isotope which decays to an alpha-emitting isotope and infusing the T-cells containing the Beta-emitting isotope which decays to an alpha-emitting isotope into the mammal. As an alternative, the treatment method may introduce into the T-cells a Beta-emitting isotope which decays to an x-ray or gamma-emitting isotope. Then, according to the alternative method, after the radioactive T- cells are infused into the mammal, the patient is monitored with a radiation detector to determine the location of T-cells containing the isotopes.

  3. 99mTc-d-penicillamine-glucuronide: synthesis, radiolabeling, in vitro and in vivo evaluation.

    PubMed

    Teksöz, Serap; Içhedef, Ciğdem Acar; Ozyüncü, Seniha; Müftüler, Fazilet Zümrüt Biber; Unak, Perihan; Medine, Ilker Emin; Ertay, Türkan; Eren, Mine Şencan

    2011-10-01

    The current study was aimed at synthesizing a glucuronide derivative of D-penicillamine (D-PA) to be used for imaging purposes. First of all, D-PA-glucuronide (D-PA-Glu) was synthesized by experimental treatments starting with uridine 5'-diphospho-glucuronosyltransferase enzyme rich microsome preparate. Then, the synthesized compound was labeled with technetium ((99m)Tc) by using a reduction method with stannous chloride. Quality controls were performed by using high-performance liquid chromatography and thin-layer radio chromatography (TLRC). Radiolabeling yield of (99m)Tc-D-PA-Glu was more than 98% according to TLRC results. In vitro evaluations of radiolabeled complexes were investigated on PC-3 human prostate cancer cells. (99m)Tc-D-PA-Glu exhibited more accumulation on PC-3 cells versus (99m)Tc-D-PA at 240 minutes. In order to determine its radiopharmaceutical potential, biodistribution studies were carried out in male Albino Wistar rats. The biodistribution results of (99m)Tc-D-PA-Glu, showed the highest uptake in prostate at 120 minutes postinjection with the main excretion route being through kidneys and bladder. (99m)Tc-D-PA-Glu and (99m)Tc-D-PA have exhibited different biodistribution results.

  4. Effects of radiolabelled monoclonal antibody infusion on blood leukocytes in cancer patients

    SciTech Connect

    Gridley, D.S.; Slater, J.M.; Stickney, D.R. )

    1990-01-01

    This study was undertaken to investigate the effects of a single infusion of radiolabelled murine monoclonal antibody (MAb) on peripheral blood leukocytes in cancer patients. Eleven patients with disseminated colon cancer, malignant melanoma, or lung adenocarcinoma were infused with 111In-labelled anti-ZCE 025, anti-p97 type 96.5c, or LA 20207 MAb, respectively. Blood samples were obtained before infusion, immediately after infusion (1 hr), and at 4 and 7 days postinfusion. Flow cytometry analysis of CD3+, CD4+, CD8+, CD16+, and CD19+ lymphocytes showed increasing CD4:CD8 ratios in seven patients after infusion. This phenomenon was not restricted to antibody subclass or to type of cancer. Two of the remaining patients exhibited a marked post-infusion increase in CD8+ cells. In all three patients with malignant melanoma, decreasing levels of CD16+ lymphocytes were noted after infusion and natural killer cell cytotoxicity showed fluctuations which paralleled the changes in the CD16+ subpopulation. Oxygen radical production by phagocytic cells was markedly affected in three subjects. These results suggest that a single infusion of radiolabelled murine MAb may alter the balance of critical lymphocyte subpopulations and modulate other leukocyte responses in cancer patients.

  5. Radiolabeled porphyrin versus gallium-67 citrate for the detection of human melanoma in athymic mice

    SciTech Connect

    Maric, N.; Chan, S. Ming; Hoffer, P.B.; Duray, P.

    1987-01-01

    We performed the biodistribution and imaging studies of /sup 111/In and /sup 67/Ga labeled tetra(4-N-methylpyridyl) porphine, (T4NMPYP), and compared it to that of /sup 67/Ga citrate in athymic mice bearing a human melanoma xenograft. The biodistribution results of both /sup 111/In and /sup 67/Ga labeled T4NMPYP (3, 6, 24, and 48 hours) were similar but differed from that of /sup 67/Ga citrate (48 hours). The optimum tumor uptake of both radiolabeled porphyrins was at 6 hours postinjection and was lower than the tumor uptake of /sup 67/Ga citrate at 48 hours postinjection. Kidney was the only organ showing higher uptake of radiolabeled porphyrin compared to that of /sup 67/Ga citrate. The imaging studies performed with /sup 111/In T4NMPYP and /sup 67/Ga citrate correspond to the biodistribution results. Osteomyelitis present in one mouse showed good localization of /sup 111/In T4NMPYP. 15 refs., 3 figs., 5 tabs.

  6. Gastrointestinal behavior of orally administered radiolabeled erythromycin pellets in man as determined by gamma scintigraphy

    SciTech Connect

    Digenis, G.A.; Sandefer, E.P.; Parr, A.F.; Beihn, R.; McClain, C.; Scheinthal, B.M.; Ghebre-Sellassie, I.; Iyer, U.; Nesbitt, R.U.; Randinitis, E. )

    1990-07-01

    The behavior of single 250-mg doses of a multiparticulate form of erythromycin base (ERYC(R)), each including five pellets radiolabeled with neutron-activated samarium-153, was observed by gamma scintigraphy in seven male subjects under fasting and nonfasting conditions. The residence time and locus of radiolabeled pellets within regions of the gastrointestinal tract were determined and were correlated with plasma concentrations of erythromycin at coincident time points. Administration of food 30 minutes postdosing reduced fasting plasma erythromycin Cmax and area under the plasma erythromycin versus time curve (AUC) values by 43% and 54%, respectively. Mean peak plasma concentration of erythromycin (Cmax) in the fasting state was 1.64 micrograms/mL versus 0.94 micrograms/mL in the nonfasting state. Total oral bioavailability, as determined by mean AUC (0-infinity) of the plasma erythromycin concentration versus time curve, was 7.6 hr/micrograms/mL in the fasted state, versus 3.5 hr/micrograms/mL in the nonfasting state. Mean time to peak plasma erythromycin concentration (tmax) in the fasting state was 3.3 hours, versus 2.3 hours in the nonfasting state. Plasma concentrations of erythromycin in both fasting and nonfasting states were within acceptable therapeutic ranges.

  7. Biokinetics of radiolabeled monoclonal antibodies in heterotransplanted nude rats: Evaluation of corrected specific tissue uptake

    SciTech Connect

    Ingvar, C.; Norrgren, K.; Strand, S.E.; Brodin, T.; Joensson, P.E.S.; Sjoegren, H.O. )

    1989-07-01

    A tumor model is presented to study the biokinetics and localization of radiolabeled monoclonal antibodies (MAb) in the nude rat (Rowett RNu/RNu) heterotransplanted with human melanoma metastases. The nude rat is larger, less sensitive, and lives longer than the nude mouse. It is, therefore, well suited for in vivo studies of tumor localization with radiolabeled monoclonal antibodies. The tumor-to-host weight ratio was closer to the human situation for the nude rat than for the mouse, and quantitative imaging could be performed with a parallel hole collimator. We followed the antibody biokinetics for as long as 8 days, with repeated blood sampling and imaging. Specific uptake of MAb was higher in tumor tissue than in all other tissues except blood. Initial high uptake was also recorded in the bone marrow. The lymph glands showed a slow uptake of specific and control antibody. A simple in vitro correction procedure is described to calculate the corrected specific tissue uptake (STUcorr) that takes the blood activity into account. Thus it was shown that 80% of the tissue uptake in the dissected liver at 30 hr was due to labeled antibodies circulating in the blood. The specific tissue uptake ratio of antibodies 96.5 and OKT3 (nonspecific control) was unity for all other organs except for tumor tissue, where the ratio was greater than two and even higher when correction for blood content of labeled antibody was made.

  8. Use of computed tomography and radiolabeled leukocytes in a cat with pancreatitis.

    PubMed

    Head, Laurie L; Daniel, Gregory B; Becker, Timothy J; Lidbetter, David A

    2005-01-01

    The normal feline pancreas has been evaluated using radiolabeled leukocytes (99mTc-HMPAO) and computed tomography. The purpose of this report is to describe a clinical case where both modalities were utilized to assess the inflamed feline pancreas. A nine year old female cat presented with anorexia, depression and some vomiting. Blood values were unremarkable. Radiographs and ultrasound were suggestive of pancreatitis. The cat's leukocytes were separated and labeled according to an established protocol. Whole body images were acquired immediately, at 5 and 30 min, and at 1, 2, 4, and 17 hours post injection. Approximately 48 h later, the animal was anesthetized and computed tomography of the abdomen was preformed both pre and post contrast. Surgical biopsies were taken. The distribution of the WBCs was similar to that documented in normal animals, however, at 2 h there was faint uptake seen in the region of the pancreas. This uptake became more intense at 4 h and persisted at 17 h. Computed tomography showed irregular margination of the pancreas, it was larger than normal and inhomogeneous. Contrast enhancement was inhomogeneous and its peak enhancement was not reached until 10 min post injection; normal feline pancreas enhances homogeneously and peaks immediately. Histopathology confirmed pancreatitis with lymphocytic, plasmacytic, neutrophilic and eosinophilic inflammation and fibrosis. Radiolabeled leukocytes can be used to document pancreatic inflammation and this is best seen 4 h after injection. Computed tomography allows superior visualization of the pancreas. Both the appearance and contrast enhancement pattern of the inflamed pancreas differ from normal.

  9. Peptide Based Radiopharmaceuticals: Specific Construct Approach

    SciTech Connect

    Som, P; Rhodes, B A; Sharma, S S

    1997-10-21

    The objective of this project was to develop receptor based peptides for diagnostic imaging and therapy. A series of peptides related to cell adhesion molecules (CAM) and immune regulation were designed for radiolabeling with 99mTc and evaluated in animal models as potential diagnostic imaging agents for various disease conditions such as thrombus (clot), acute kidney failure, and inflection/inflammation imaging. The peptides for this project were designed by the industrial partner, Palatin Technologies, (formerly Rhomed, Inc.) using various peptide design approaches including a newly developed rational computer assisted drug design (CADD) approach termed MIDAS (Metal ion Induced Distinctive Array of Structures). In this approach, the biological function domain and the 99mTc complexing domain are fused together so that structurally these domains are indistinguishable. This approach allows construction of conformationally rigid metallo-peptide molecules (similar to cyclic peptides) that are metabolically stable in-vivo. All the newly designed peptides were screened in various in vitro receptor binding and functional assays to identify a lead compound. The lead compounds were formulated in a one-step 99mTc labeling kit form which were studied by BNL for detailed in-vivo imaging using various animals models of human disease. Two main peptides usingMIDAS approach evolved and were investigated: RGD peptide for acute renal failure and an immunomodulatory peptide derived from tuftsin (RMT-1) for infection/inflammation imaging. Various RGD based metallopeptides were designed, synthesized and assayed for their efficacy in inhibiting ADP-induced human platelet aggregation. Most of these peptides displayed biological activity in the 1-100 µM range. Based on previous work by others, RGD-I and RGD-II were evaluated in animal models of acute renal failure. These earlier studies showed that after acute ischemic injury the renal cortex displays

  10. [SYNTHETIC PEPTIDE VACCINES].

    PubMed

    Sergeyev, O V; Barinsky, I F

    2016-01-01

    An update on the development and trials of synthetic peptide vaccines is reviewed. The review considers the successful examples of specific protection as a result of immunization with synthetic peptides using various protocols. The importance of conformation for the immunogenicity of the peptide is pointed out. An alternative strategy of the protection of the organism against the infection using synthetic peptides is suggested.

  11. Patched targeting peptides for imaging and treatment of hedgehog positive breast tumors.

    PubMed

    Smith, Daniel; Kong, Fanlin; Yang, David; Larson, Richard; Sims-Mourtada, Jennifer; Woodward, Wendy A

    2014-01-01

    High tumor hedgehog expression is correlated with poor prognosis in invasive ductal carcinoma. Peptides which bind the patched receptor have recently been reported to have a growth inhibitory effect in tumors with activated hedgehog signaling. We sought to examine growth inhibition with these peptides in breast cancer cells and use these peptides as molecular imaging probes to follow changes in hedgehog expression after chemotherapy. Significant growth inhibition was observed in breast cancer cell lines treated with PTCH-blocking peptides. Significant in vitro uptake was observed with both FITC- and (99m)Tc-EC-peptide conjugates. In vivo imaging studies displayed greater accumulation of (99m)Tc-labeled peptides within tumors as compared to adjacent muscle tissue. Patched receptor expression increased after treatment and this correlated with an increase in tumor radiotracer uptake. These studies suggest that peptides which bind the sonic hedgehog docking site in patched receptor correlate with patched expression and can be used to image patched in vivo. Further, our data suggest that radiolabeled peptides may enable us to examine the activity of the hedgehog signaling pathway and to evaluate response to anti-cancer therapies.

  12. Space analogue studies in Antarctica

    NASA Astrophysics Data System (ADS)

    Lugg, D.; Shepanek, M.

    1999-09-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mltogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  13. Condensed matter analogues of cosmology

    NASA Astrophysics Data System (ADS)

    Kibble, Tom; Srivastava, Ajit

    2013-10-01

    It is always exciting when developments in one branch of physics turn out to have relevance in a quite different branch. It would be hard to find two branches farther apart in terms of energy scales than early-universe cosmology and low-temperature condensed matter physics. Nevertheless ideas about the formation of topological defects during rapid phase transitions that originated in the context of the very early universe have proved remarkably fruitful when applied to a variety of condensed matter systems. The mathematical frameworks for describing these systems can be very similar. This interconnection has led to a deeper understanding of the phenomena in condensed matter systems utilizing ideas from cosmology. At the same time, one can view these condensed matter analogues as providing, at least in a limited sense, experimental access to the phenomena of the early universe for which no direct probe is possible. As this special issue well illustrates, this remains a dynamic and exciting field. The basic idea is that when a system goes through a rapid symmetry-breaking phase transition from a symmetric phase into one with spontaneously broken symmetry, the order parameter may make different choices in different regions, creating domains that when they meet can trap defects. The scale of those domains, and hence the density of defects, is constrained by the rate at which the system goes through the transition and the speed with which order parameter information propagates. This is what has come to be known as the Kibble-Zurek mechanism. The resultant scaling laws have now been tested in a considerable variety of different systems. The earliest experiments illustrating the analogy between cosmology and condensed matter were in liquid crystals, in particular on the isotropic-to-nematic transition, primarily because it is very easy to induce the phase transition (typically at room temperature) and to image precisely what is going on. This field remains one of the

  14. Space analogue studies in Antarctica.

    PubMed

    Lugg, D; Shepanek, M

    1999-01-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  15. Space analogue studies in Antarctica

    NASA Technical Reports Server (NTRS)

    Lugg, D.; Shepanek, M.

    1999-01-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  16. Purification of an angiotensin II binding protein by using antibodies to a peptide encoded by angiotensin II complementary RNA

    SciTech Connect

    Elton, T.S.; Dion, L.D.; Bost, K.L.; Oparil, S.; Blalock, J.E.

    1988-04-01

    The authors have generated a monospecific antibody to a synthetic peptide encoded by an RNA complementary to the mRNA for angiotensin II (AII) and determined whether this antibody recognizes the AII receptor. They demonstrate that the antibody competes specifically with /sup 125/I-labeled AII for the same binding site on rat adrenal membranes. Furthermore, they show this antibody inhibits the secretion of aldosterone from cultured rat adrenal cells, suggesting that the antibody recognizes the biologically relevant AII receptor. Finally, they demonstrate that antibody to the complementary peptide can be used to immunoaffinity-purify a protein of M/sub r/ 66,000 that specifically binds radiolabeled AII.

  17. Peptide Bacteriocins--Structure Activity Relationships.

    PubMed

    Etayash, Hashem; Azmi, Sarfuddin; Dangeti, Ramana; Kaur, Kamaljit

    2015-01-01

    With the growing concerns in the scientific and health communities over increasing levels of antibiotic resistance, antimicrobial peptide bacteriocins have emerged as promising alternatives to conventional small molecule antibiotics. A substantial attention has recently focused on the utilization of bacteriocins in food preservation and health safety. Despite the fact that a large number of bacteriocins have been reported, only a few have been fully characterized and structurally elucidated. Since knowledge of the molecular structure is a key for understanding the mechanism of action and therapeutic effects of peptide, we centered our focus in this review on the structure-activity relationships of bacteriocins with a particular focus in seven bacteriocins, namely, nisin, microcin J25, microcin B17, microcin C, leucocin A, sakacin P, and pediocin PA-1. Significant structural changes responsible for the altered activity of the recent bacteriocin analogues are discussed here.

  18. Peptide Bond Formation in Water Mediated by Carbon Disulfide.

    PubMed

    Leman, Luke J; Huang, Zheng-Zheng; Ghadiri, M Reza

    2015-09-01

    Demonstrating plausible nonenzymatic polymerization mechanisms for prebiotic monomers represents a fundamental goal in prebiotic chemistry. While a great deal is now known about the potentially prebiotic synthesis of amino acids, our understanding of abiogenic polymerization processes to form polypeptides is less well developed. Here, we show that carbon disulfide (CS2), a component of volcanic emission and sulfide mineral weathering, and a widely used synthetic reagent and solvent, promotes peptide bond formation in modest yields (up to ∼20%) from α-amino acids under mild aqueous conditions. Exposure of a variety of α-amino acids to CS2 initially yields aminoacyl dithiocarbamates, which in turn generate reactive 2-thiono-5-oxazolidone intermediates, the thio analogues of N-carboxyanhydrides. Along with peptides, thiourea and thiohydantoin species are produced. Amino acid stereochemistry was preserved in the formation of peptides. Our findings reveal that CS2 could contribute to peptide bond formation, and possibly other condensation reactions, in abiogenic settings.

  19. Inhibition of plant-pathogenic bacteria by short synthetic cecropin A-melittin hybrid peptides.

    PubMed

    Ferre, Rafael; Badosa, Esther; Feliu, Lidia; Planas, Marta; Montesinos, Emili; Bardají, Eduard

    2006-05-01

    Short peptides of 11 residues were synthesized and tested against the economically important plant pathogenic bacteria Erwinia amylovora, Pseudomonas syringae, and Xanthomonas vesicatoria and compared to the previously described peptide Pep3 (WKLFKKILKVL-NH(2)). The antimicrobial activity of Pep3 and 22 analogues was evaluated in terms of the MIC and the 50% effective dose (ED(50)) for growth. Peptide cytotoxicity against human red blood cells and peptide stability toward protease degradation were also determined. Pep3 and several analogues inhibited growth of the three pathogens and had a bactericidal effect at low micromolar concentrations (ED(50) of 1.3 to 7.3 microM). One of the analogues consisting of a replacement of both Trp and Val with Lys and Phe, respectively, resulted in a peptide with improved bactericidal activity and minimized cytotoxicity and susceptibility to protease degradation compared to Pep3. The best analogues can be considered as potential lead compounds for the development of new antimicrobial agents for use in plant protection either as components of pesticides or expressed in transgenic plants.

  20. Inhibition of Plant-Pathogenic Bacteria by Short Synthetic Cecropin A-Melittin Hybrid Peptides

    PubMed Central

    Ferre, Rafael; Badosa, Esther; Feliu, Lidia; Planas, Marta; Montesinos, Emili; Bardají, Eduard

    2006-01-01

    Short peptides of 11 residues were synthesized and tested against the economically important plant pathogenic bacteria Erwinia amylovora, Pseudomonas syringae, and Xanthomonas vesicatoria and compared to the previously described peptide Pep3 (WKLFKKILKVL-NH2). The antimicrobial activity of Pep3 and 22 analogues was evaluated in terms of the MIC and the 50% effective dose (ED50) for growth. Peptide cytotoxicity against human red blood cells and peptide stability toward protease degradation were also determined. Pep3 and several analogues inhibited growth of the three pathogens and had a bactericidal effect at low micromolar concentrations (ED50 of 1.3 to 7.3 μM). One of the analogues consisting of a replacement of both Trp and Val with Lys and Phe, respectively, resulted in a peptide with improved bactericidal activity and minimized cytotoxicity and susceptibility to protease degradation compared to Pep3. The best analogues can be considered as potential lead compounds for the development of new antimicrobial agents for use in plant protection either as components of pesticides or expressed in transgenic plants. PMID:16672470

  1. The metal loading ability of beta-amyloid N-terminus: a combined potentiometric and spectroscopic study of copper(II) complexes with beta-amyloid(1-16), its short or mutated peptide fragments, and its polyethylene glycol (PEG)-ylated analogue.

    PubMed

    Damante, Chiara A; Osz, Katalin; Nagy, Zoltán; Pappalardo, Giuseppe; Grasso, Giulia; Impellizzeri, Giuseppe; Rizzarelli, Enrico; Sóvágó, Imre

    2008-10-20

    Alzheimer's disease (AD) is becoming a rapidly growing health problem, as it is one of the main causes of dementia in the elderly. Interestingly, copper(II) (together with zinc and iron) ions are accumulated in amyloid deposits, suggesting that metal binding to Abeta could be involved in AD pathogenesis. In Abeta, the metal binding is believed to occur within the N-terminal region encompassing the amino acid residues 1-16. In this work, potentiometric, spectroscopic (UV-vis, circular dichroism, and electron paramagnetic resonance), and electrospray ionization mass spectrometry (ESI-MS) approaches were used to investigate the copper(II) coordination features of a new polyethylene glycol (PEG)-conjugated Abeta peptide fragment encompassing the 1-16 amino acid residues of the N-terminal region (Abeta(1-16)PEG). The high water solubility of the resulting metal complexes allowed us to obtain a complete complex speciation at different metal-to-ligand ratios ranging from 1:1 to 4:1. Potentiometric and ESI-MS data indicate that Abeta(1-16)PEG is able to bind up to four copper(II) ions. Furthermore, in order to establish the coordination environment at each metal binding site, a series of shorter peptide fragments of Abeta, namely, Abeta(1-4), Abeta(1-6), AcAbeta(1-6), and AcAbeta(8-16)Y10A, were synthesized, each encompassing a potential copper(II) binding site. The complexation properties of these shorter peptides were also comparatively investigated by using the same experimental approach.

  2. Specific binding sites for muramyl peptides on murine macrophages

    SciTech Connect

    Silverman, D.H.S.; Krueger, J.M.; Karnovsky, M.L.

    1986-03-15

    Two radiolabeled (/sup 125/I) muramyl peptide derivatives of high specific activity were prepared: a tripeptide with an iodinated C-terminal tyrosine methyl ester (Ligand I), and a muramyl tripeptide with a C-terminal lysine derivatized with Bolton-Hunter reagent (Ligand II). These were used to characterize binding of muramyl peptides to monolayers of murine macrophages. Saturable high-affinity binding to resident, caseinate-elicited, and Listeria-activated peritoneal cells was observed with both radioligands. Binding affinities varied with the state of activation of the macrophages, and K/sub D/ values ranged from 48 +/- 33 pM (for resident macrophages, Ligand I) to 1020 +/- 90 pM (for activated macrophages, Ligand II). Specific binding sites were also found on a macrophage-derived cell line. The ability of several unlabeled muramyl peptides to compete with Ligands I and II for their binding sites was tested. Competition was stereospecific and correlated with known biological activities of these compounds (i.e., immunoadjuvanticity, pyrogenicity, and somnogenicity). The sites identified here for Ligands I and II may mediate some of the effects that muramyl peptides have previously been demonstrated to have on macrophages.

  3. Ectopic serotonin accumulation and efflux in rat mesencephalic slices after prior tissue 'radiolabelling'.

    PubMed

    Blatchford, Karen L; McLaughlin, Daniel P; Stamford, Jonathan A

    2003-06-30

    Radiolabelling of brain tissue has long been used to facilitate detection of transmitter efflux, on the assumption that egress of tritiated monoamines reflects that of the endogenous transmitter. The present study tested the hypothesis that the application of exogenous serotonin (5-HT) to mesencephalic slices, in the manner used during a typical radiolabelling protocol, leads to efflux of 5-HT from physiologically inappropriate loci such as other non-serotonergic neurones. We used fast cyclic voltammetry (FCV) to determine the effect of tissue pre-incubation with 5-HT on electrically-stimulated 5-HT efflux and reuptake in rat mesencephalic slices. Seven subregions were studied, including the dorsal raphe nucleus (DRN), dorsomedial periaqueductal grey (PAGdm) and the oral part of the pontine reticular nucleus (PnO). In control slices (pre-incubated without 5-HT), stimulated 5-HT efflux was only detectable in DRN, PAGdm and occasionally in PnO. In slices incubated in 5-HT (100nM) for 30min, stimulated 5-HT efflux was detected in all seven subregions studied. In such slices, citalopram (75nM) increased efflux and reuptake t(1/2) in DRN to 201+/-21 and 487+/-117% of pre-drug values (P<0.05) but had no significant effect on either measure in PnO. The 5-HT1 autoreceptor agonist, 5-carboxamidotryptamine (5-CT, 100nM) decreased efflux in DRN by 54+/-6% (P<0.05), but was without effect (10+/-14%) in PnO. The present results show that pre-incubation in 5-HT allows stimulated 5-HT efflux from regions of the mesencephalon other than DRN and PAGdm. This stimulated 5-HT efflux is apparently not influenced by 5-HT transporters or 5-HT1 autoreceptors, suggesting that efflux is ectopic, an artefact of the pre-incubation process. In summary, incubation of rat mesencephalic tissue in 5-HT, in the manner of a typical radiolabelling protocol, results in stimulated 5-HT efflux from non-physiological sites. The results of such transmitter efflux studies should thus be interpreted with

  4. Rationally designed cyclic analogues of luteinizing hormone-releasing hormone: enhanced enzymatic stability and biological properties.

    PubMed

    Laimou, Despina; Katsila, Theodora; Matsoukas, John; Schally, Andrew; Gkountelias, Kostas; Liapakis, George; Tamvakopoulos, Constantin; Tselios, Theodore

    2012-12-01

    This article describes the rational design, synthesis and pharmacological properties of amide-linked cyclic analogues of Luteinizing Hormone-Releasing Hormone (LHRH) with substitutions at positions 1 (Pro), 6 (D-Leu/D-Trp), 9 (Aze) and 10 (BABA/Acp). These LHRH analogues fulfil the conformational requirements that are known in the literature (bend in the 5-8 segment) to be essential for receptor recognition and activation. Although, they are characterised by an overall low binding affinity to the LHRH-I receptor, the cyclic analogues that were studied and especially the cyclo(1-10)[Pro(1), D-Leu(6), BABA(10)] LHRH, exhibit a profoundly enhanced in vitro and in vivo stability and improved pharmacokinetics in comparison with their linear counterpart and leuprolide. Upon receptor binding, cyclo(1-10)[Pro(1), D-Leu(6), BABA(10)] LHRH causes testosterone release in C57/B16 mice (in vivo efficacy) that is comparable to that of leuprolide. Testosterone release is an acutely dose dependent effect that is blocked by the LHRH-I receptor antagonist, cetrorelix. The pharmacokinetic advantages and efficacy of cyclo(1-10)[Pro(1), D-Leu(6), BABA(10)] LHRH render this analogue a promising platform for future rational drug design studies towards the development of non-peptide LHRH mimetics.

  5. Peptide assemblies: from cell scaffolds to immune adjuvants

    NASA Astrophysics Data System (ADS)

    Collier, Joel

    2011-03-01

    This talk will discuss two interrelated aspects of peptide self-assemblies in biological applications: their use as matrices for regenerative medicine, and their use as chemically defined adjuvants for directing immune responses against engineered antigens. In the first half of the presentation, the design of peptide self-assemblies as analogues for the extracellular matrix will be described, with a focus on self-assemblies displaying multiple different cell-binding peptides. We conducted multi-factorial investigations of peptide co-assemblies containing several different ligand-bearing peptides using statistical ``design of experiments'' (DoE). Using the DoE techniques of factorial experimentation and response surface modeling, we systematically explored how precise combinations of ligand-bearing peptides modulated endothelial cell growth, in the process finding interactions between ligands not previously appreciated. By investigating immune responses against the materials intended for tissue engineering applications, we discovered that the basic self-assembling peptides were minimally immunogenic or non-immunogenic, even when delivered in strong adjuvants. -But when they were appended to an appropriately restricted epitope peptide, these materials raised strong and persistent antibody responses. These responses were dependent on covalent conjugation between the epitope and self-assembling domains of the peptides, were mediated by T cells, and could be directed towards both peptide epitopes and conjugated protein antigens. In addition to their demonstrated utility as scaffolds for regenerative medicine, peptide self-assemblies may also be useful as chemically defined adjuvants for vaccines and immunotherapies. This work was funded by NIH/NIDCR (1 R21 DE017703-03), NIH/NIBIB (1 R01 EB009701-01), and NSF (CHE-0802286).

  6. N-Formylmethionyl Peptide Receptors on Equine Leukocytes Initiate Secretion but not Chemotaxis

    NASA Astrophysics Data System (ADS)

    Snyderman, Ralph; Pike, Marilyn C.

    1980-07-01

    The chemotaxis of leukocytes appears to be initiated by the binding of chemotactic factors to the surface of these cells. N-Formylated peptides induce chemotaxis and lysosomal enzyme secretion of leukocytes; because these peptides are available in a purified radiolabeled form, they have been useful in the characterization of receptors for chemotactic factors. Equine polymorphonuclear leukocytes secrete lysosomal enzymes but do not exhibit chemotaxis in response to the N-formylated peptides, even though they have a high-affinity cell surface receptor for these agents. The specificity of the equine receptor resembles the specificity of the receptor on chemotactically responsive leukocytes from other species. Equine polymorphonuclear leukocytes may thus be an excellent model for the study of the events that lead to a biological response following receptor occupancy.

  7. Synthesis, biological evaluation and structural characterization of novel glycopeptide analogues of nociceptin N/OFQ.

    PubMed

    Arsequell, Gemma; Rosa, Mònica; Mayato, Carlos; Dorta, Rosa L; Gonzalez-Nunez, Verónica; Barreto-Valer, Katherine; Marcelo, Filipa; Calle, Luis P; Vázquez, Jesús T; Rodríguez, Raquel E; Jiménez-Barbero, Jesús; Valencia, Gregorio

    2011-09-07

    To examine if the biological activity of the N/OFQ peptide, which is the native ligand of the pain-related and viable drug target NOP receptor, could be modulated by glycosylation and if such effects could be conformationally related, we have synthesized three N/OFQ glycopeptide analogues, namely: [Thr(5)-O-α-D-GalNAc-N/OFQ] (glycopeptide 1), [Ser(10)-O-α-D-GalNAc]-N/OFQ (glycopeptide 2) and [Ser(10)-O-β-D-GlcNAc]-N/OFQ] (glycopeptide 3). They were tested for biological activity in competition binding assays using the zebrafish animal model in which glycopeptide 2 exhibited a slightly improved binding affinity, whereas glycopeptide 1 showed a remarkably reduced binding affinity compared to the parent compound and glycopeptide 3. The structural analysis of these glycopeptides and the parent N/OFQ peptide by NMR and circular dichroism indicated that their aqueous solutions are mainly populated by random coil conformers. However, in membrane mimic environments a certain proportion of the molecules of all these peptides exist as α-helix structures. Interestingly, under these experimental conditions, glycopeptide 1 (glycosylated at Thr-5) exhibited a population of folded hairpin-like geometries. From these facts it is tempting to speculate that nociceptin analogues showing linear helical structures are more complementary and thus interact more efficiently with the native NOP receptor than folded structures, since glycopeptide 1 showed a significantly reduced binding affinity for the NOP receptor.

  8. Microbial uptake of radiolabeled substrates: estimates of growth rates from time course measurements.

    PubMed Central

    Li, W K

    1984-01-01

    The uptake of [3H]glucose and a mixture of 3H-labeled amino acids was measured, in time course fashion, in planktonic microbial assemblages of the eastern tropical Pacific Ocean. The average generation times of those portions of the assemblages able to utilize these substrates were estimated from a simple exponential growth model. Other workers have independently used this model in its integrated or differential form. A mathematical verification and an experimental demonstration of the equivalence of the two approaches are presented. A study was made of the size distribution of heterotrophic activity, using time course measurements. It was found that the size distribution and the effect of sample filtration before radiolabeling were dependent on time of incubation. In principle, it was possible to ascribe these time dependences to differences in the specific growth rate and initial standing stock of the microbial assemblages. PMID:6696414

  9. Laboratory model ecosystem evaluation of the chemical and biological behavior of radiolabeled micropollutants.

    PubMed

    Metcalf, R L

    1976-01-01

    A standardized laboratory model ecosystem has been used to evaluate the comparative behavior of radiolabeled micropollutants including organochlorine, organophosphorus, carbamate, and hormone-mimic insecticides; herbicides; important industrial organic compounds including phthalate esters and PCB's; and specific pollutants such as TCBD and hexachlorobenzene. The compounds have been studies for ecological effects over a terrestrial-aquatic interface and through several food chains, especially with regard to the development of quantitative information on ecological magnification and biodegradability index. The pathways of chemical degradation in the various organisms have been evaluated and the ecological effects of degradation products investigated. Illustrations are given of the use of the model ecosystem technology for screening new candidate pesticides for effects on environmental quality; for evaluating the hazards of environmental pollution by industrial waste effluents; and for fundamental studies of the principles fo biodegradability of organic chemicals in a variety of organisms.

  10. Radiolabeling of intact dosage forms by neutron activation: effects on in vitro performance

    SciTech Connect

    Parr, A.; Jay, M.

    1987-12-01

    Compressed tablets containing various quantities of stable isotopes of Ba, Er, and Sm for use in neutron activation studies were evaluated for the effect of stable isotope incorporation on tablet hardness and disintegration times. At concentrations likely to be used in scintigraphic studies employing neutron activation as a radiolabeling method, no significant effect on in vitro parameters were observed. While the incorporation of stable isotopes influenced tablet hardness to a greater degree than disintegration time, irradiation of tablets in a neutron flux of 4.4 x 10(13) n/cm2 sec had a direct effect on tablet disintegration time. Thus, future neutron activation studies should focus on minimizing the amount of stable isotope to be incorporated with the formulation while using the shortest feasible irradiation time.

  11. Two versatile eukaryotic vectors permitting epitope tagging, radiolabelling and nuclear localisation of expressed proteins.

    PubMed

    Georgiev, O; Bourquin, J P; Gstaiger, M; Knoepfel, L; Schaffner, W; Hovens, C

    1996-02-12

    Two versatile eukaryotic expression vectors have been developed which permit the production of an epitope-tagged cDNA insert by transient transfection in mammalian cells or by in vitro transcription-translation. The first vector, pCATCH, can be used to clone cDNA inserts in three different frames via eight unique restriction sites in a multiple cloning site (MCS) located downstream from both the FLAG epitope and the specific heart muscle kinase phosphorylation site, conferring the possibility of in vitro radiolabelling. A specific protease cleavage site enables the removal of the FLAG epitope, simplifying affinity purification of recombinant CATCH proteins. pCATCH possesses stop codons in all three reading frames at the 3' terminal end of the MCS. A derivate of this vector, pCATCH-NLS, was constructed by incorporating an SV40 nuclear localisation signal upstream from the MCS, for directed localisation of the tagged proteins.

  12. Synthesis, conjugation, and radiolabeling of a novel bifunctional chelating agent for (225)Ac radioimmunotherapy applications.

    PubMed

    Chappell, L L; Deal, K A; Dadachova, E; Brechbiel, M W

    2000-01-01

    225Ac (t(1/2) = 10 days) is an alternative alpha-emitter that has been proposed for radioimmunotherapy (RIT) due to its many favorable properties, such as half-life and mode of decay. The factor limiting use of (225)Ac in RIT is the lack of an acceptably stable chelate for in vivo applications. Herein is described the first reported bifunctional chelate for (225)Ac that has been evaluated for stability for in vivo applications. The detailed synthesis of a bifunctional chelating agent 2-(4-isothiocyanatobenzyl)-1,4,7,10,13, 16-hexaazacyclohexadecane- 1,4,7,10,13,16-hexaacetic acid (HEHA-NCS) is reported. This ligand was conjugated to three monoclonal antibodies, CC49, T101, and BL-3 with chelate-to-protein ratios between 1.4 and 2. The three conjugates were radiolabeled with (225)Ac, and serum stability study of the [(225)Ac]BL-3-HEHA conjugate was performed.

  13. Structure-function relationships and conformational properties of alpha-MSH(6-13) analogues with candidacidal activity.

    PubMed

    Carotenuto, Alfonso; Saviello, Maria Rosaria; Auriemma, Luigia; Campiglia, Pietro; Catania, Anna; Novellino, Ettore; Grieco, Paolo

    2007-01-01

    Alpha-melanocyte-stimulating hormone (alpha-MSH) is an endogenous linear tridecapeptide with potent anti-inflammatory effects. We firstly demonstrated that alpha-MSH and its C-terminal sequence Lys-Pro-Val [alpha-MSH(11-13)] have antimicrobial effects against two major and representative pathogens: Staphylococcus aureus and Candida albicans. Successively, in an attempt to improve the candidacidal activity of alpha-MSH and to better understand the peptide structure-antifungal activity relations, we have recently designed and synthesized novel peptide analogues. We focused on the sequence alpha-MSH(6-13), which contains the invariant melanocortin core sequence His-Phe-Arg-Trp (6-9) and also contains the sequence Lys-Pro-Val (11-13) important for antimicrobial activity. In that structure-activity study, we discovered several compounds that have greater candidacidal activity than alpha-MSH, among which the peptide [d-Nal-7,Phe-12]-alpha-MSH(6-13) was the most potent. Here, we report a detailed conformational analysis by spectroscopic and computational methods of three peptides, alpha-MSH(6-13) (1), [d-Nal-7,Phe-12]-alpha-MSH(6-13) (2) and [d-Nal-7,Asp-12]-alpha-MSH(6-13) (3). Peptides were chosen on the basis of their candidacidal activities and were studied in membrane mimetic environment (SDS micelles). Different turn structures were observed for the three peptides and a conformation-activity model was developed based on these results. This study offers a structural basis for the design of novel peptide and non-peptide analogues to be used as new antimicrobial agents.

  14. Facile method to radiolabel glycol chitosan nanoparticles with (64)Cu via copper-free click chemistry for MicroPET imaging.

    PubMed

    Lee, Dong-Eun; Na, Jin Hee; Lee, Sangmin; Kang, Choong Mo; Kim, Hun Nyun; Han, Seung Jin; Kim, Hyunjoon; Choe, Yearn Seong; Jung, Kyung-Ho; Lee, Kyo Chul; Choi, Kuiwon; Kwon, Ick Chan; Jeong, Seo Young; Lee, Kyung-Han; Kim, Kwangmeyung

    2013-06-03

    An efficient and straightforward method for radiolabeling nanoparticles is urgently needed to understand the in vivo biodistribution of nanoparticles. Herein, we investigated a facile and highly efficient strategy to prepare radiolabeled glycol chitosan nanoparticles with (64)Cu via a strain-promoted azide-alkyne cycloaddition strategy, which is often referred to as click chemistry. First, the azide (N3) group, which allows for the preparation of radiolabeled nanoparticles by copper-free click chemistry, was incorporated to glycol chitosan nanoparticles (CNPs). Second, the strained cyclooctyne derivative, dibenzyl cyclooctyne (DBCO) conjugated with a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelator, was synthesized for preparing the preradiolabeled alkyne complex with (64)Cu radionuclide. Following incubation with the (64)Cu-radiolabeled DBCO complex (DBCO-PEG4-Lys-DOTA-(64)Cu with high specific activity, 18.5 GBq/μmol), the azide-functionalized CNPs were radiolabeled successfully with (64)Cu, with a high radiolabeling efficiency and a high radiolabeling yield (>98%). Importantly, the radiolabeling of CNPs by copper-free click chemistry was accomplished within 30 min, with great efficiency in aqueous conditions. In addition, we found that the (64)Cu-radiolabeled CNPs ((64)Cu-CNPs) did not show any significant effect on the physicochemical properties, such as size, zeta potential, or spherical morphology. After (64)Cu-CNPs were intravenously administered to tumor-bearing mice, the real-time, in vivo biodistribution and tumor-targeting ability of (64)Cu-CNPs were quantitatively evaluated by microPET images of tumor-bearing mice. These results demonstrate the benefit of copper-free click chemistry as a facile, preradiolabeling approach to conveniently radiolabel nanoparticles for evaluating the real-time in vivo biodistribution of nanoparticles.

  15. Amygdalin analogues inhibit IFN-γ signalling and reduce the inflammatory response in human epidermal keratinocytes.

    PubMed

    Paoletti, Iole; De Gregorio, Vincenza; Baroni, Adone; Tufano, Maria Antonietta; Donnarumma, Giovanna; Perez, Juan Jesus

    2013-12-01

    Peptide T (PT), an octapeptide fragment located in the V2 region of the HIV-1 gp120-coating protein, appears to be beneficial in the treatment of psoriasis. Our previous investigations suggest that keratinocytes play a key role in conditioning the therapeutic effects of PT in psoriasis. The aim of this study was to explore the effects of PT and the peptidomimetic natural products, Dhurrin and Prunasin, on the expression of the IL-6, IL-8, IL-23, HSP70 and ICAM-1 on IFN-γ and TNF-α-NHEK activated cells. Moreover, we analysed the interference of PT and its analogues through STAT-3 activation. Our results show that the analogues tested exhibit the beneficial biological effects of PT, suggesting the primary role of keratinocytes upon which PT and the peptidomimetics act directly, by reducing proinflammatory responses. Its reduction appears to be important for therapeutic approach in psoriasis pathogenesis.

  16. Combined radiolabel-binding and immunocytochemical evaluation of receptor–ligand interactions. Studies of transferrin receptors on activated lymphocytes

    PubMed Central

    Galbraith, Gillian M. P.; Galbraith, Robert M.

    1981-01-01

    A protocol that involved both immunohistological and radiolabel-binding procedures was devised for the study of transferrin–receptor interactions. This composite approach yielded considerably more information than did either technique used alone, and also provided a simple means for exclusion of several common potential sources of error. PMID:6277297

  17. Whole organ and islet of Langerhans dosimetry for calculation of absorbed doses resulting from imaging with radiolabeled exendin

    PubMed Central

    van der Kroon, Inge; Woliner-van der Weg, Wietske; Brom, Maarten; Joosten, Lieke; Frielink, Cathelijne; Konijnenberg, Mark W.; Visser, Eric P.; Gotthardt, Martin

    2017-01-01

    Radiolabeled exendin is used for non-invasive quantification of beta cells in the islets of Langerhans in vivo. High accumulation of radiolabeled exendin in the islets raised concerns about possible radiation-induced damage to these islets in man. In this work, islet absorbed doses resulting from exendin-imaging were calculated by combining whole organ dosimetry with small scale dosimetry for the islets. Our model contains the tissues with high accumulation of radiolabeled exendin: kidneys, pancreas and islets. As input for the model, data from a clinical study (radiolabeled exendin distribution in the human body) and from a preclinical study with Biobreeding Diabetes Prone (BBDP) rats (islet-to-exocrine uptake ratio, beta cell mass) were used. We simulated 111In-exendin and 68Ga-exendin absorbed doses in patients with differences in gender, islet size, beta cell mass and radiopharmaceutical uptake in the kidneys. In all simulated cases the islet absorbed dose was small, maximum 1.38 mGy for 68Ga and 66.0 mGy for 111In. The two sources mainly contributing to the islet absorbed dose are the kidneys (33–61%) and the islet self-dose (7.5–57%). In conclusion, all islet absorbed doses are low (<70 mGy), so even repeated imaging will hardly increase the risk on diabetes. PMID:28067253

  18. An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group.

    PubMed

    Jeon, Jongho; Shim, Ha Eun; Mushtaq, Sajid; Choi, Mi Hee; Park, Sang Hyun; Choi, Dae Seong; Jang, Beom-Su

    2016-10-10

    Here, we demonstrate a detailed protocol for the radiosynthesis of a (125)I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [(125)I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified (125)I-labeled azide (1) was obtained with high radiochemical yield (75 ± 10%, n = 8) and excellent radiochemical purity (>99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the (125)I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

  19. Magnetically driven nanoparticles: (18) FDG-radiolabelling and positron emission tomography biodistribution study.

    PubMed

    De Simone, Mariarosaria; Panetta, Daniele; Bramanti, Emilia; Giordano, Cristiana; Salvatici, Maria C; Gherardini, Lisa; Menciassi, Arianna; Burchielli, Silvia; Cinti, Caterina; Salvadori, Piero A

    2016-11-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have received increasing interest as contrast media in biomedical imaging and innovative therapeutic tools, in particular for loco-regional ablative treatments and drug delivery. The future of therapeutic applications would strongly benefit from improving the capability of the nanostructured constructs to reach the selected target, in particular beyond the intravascular space. Besides the decoration of SPIONs surface with ad hoc bioactive molecules, external magnetic fields are in principle able to remotely influence SPIONs' physiological biodistribution and concentrate them to a specific anatomical region or portion of a tissue. The reduction of SPIONs administered to the body and the need for defining the effective SPIONs local concentration suggest that PET/CT may be a method to quantitatively detect the nanoparticles accumulation in vivo at low concentration and assess their tridimensional distribution in response to an external magnetic field and in relation to the local anatomy highlighted by CT imaging. Here, we report on the possibility to assess the spatial distribution of magnetically-driven radiolabelled SPIONs in a peripheral tissue (mouse thigh) with microPET/CT imaging. To this aim we labelled SPIONs using (18) F-2-fluoro-2-deoxyglucose as a synthon, by chemoselective oxime formation between its open-chain tautomer and nanoparticle amino-groups, and employed microPET/CT imaging to measure the radiolabelled construct biodistribution in a small animal model, following intravenous administration, with and without the application of a permanent magnet onto the skin. The in vivo and ex vivo results showed that micro-PET/CT was able to demonstrate the localizing action of the magnet on SPIONs and provide information, in a multimodal 3D data set, about SPIONs biodistribution taking into account the local anatomy. Copyright © 2017 John Wiley & Sons, Ltd.

  20. A radiolabeled nonapeptide probe targeting PC-3 cells and bone metastases of prostate cancer in mice.

    PubMed

    Qinghua, Wu; Jianli, Xu; Lu, Liu; Zexuan, Yang; Guansheng, Tong; Hailin, Gao; Jianwei, Jiang

    2012-01-01

    Previous investigations showed that interleukin-11 (IL-11) and the IL-11 receptor (IL-11R) are correlated with regulation of tumor progression and may play significant roles in bone metastases. The nonapeptide structure c(CGRRAGGSC) is a phage-display-selected IL-11 mimic that binds to IL-11R. The aim of this study was to synthesize radiolabeled c(CGRRAGGSC) and to investigate the possible interaction between this radioactive probe and an IL-11R-positive bone metastasis model of PC-3 prostate cancer. The molecular probe (99m)Tc-DTPA-c(CGRRAGGSC) was radiolabeled with (99m)Tc using the diethylenetriaminepentaacetic acid (DTPA) chelate. Counterstaining was performed with LSS670, a near-infrared dye. The binding sites of the molecular probe in PC-3 cells were observed under a fluorescence microscope. The binding characteristics of the labeled probe were analyzed using radioreceptor analysis. Single photon emission tomography imaging and biodistribution of the probe were investigated using xenografts of PC-3 cells into tibias of nude mice. The labeled product, (99m) Tc-DTPA-c(CGRRAGGSC), was obtained with high labeling efficiency, high radiochemical purity and good stability. The molecular probe was combined with the PC-3 cell membrane and cytoplasm through fluorescence tracing. In the saturation and competitive inhibition experiments performed in vitro, the K(d) value was 0.32 ± 0.02 n m and the B(max) value was 754 ± 34 fmol mg(-1) pro. The probe exhibited a high tumor uptake in vivo. The radioactive molecular probe (99m) Tc-DTPA-c(CGRRAGGSC) may be used as a specific molecular imaging agent for detecting IL-11R overexpression in tumors and bone metastasis, such as prostate cancers.

  1. Noninvasive imaging of radiolabeled exosome-mimetic nanovesicle using 99mTc-HMPAO

    PubMed Central

    Hwang, Do Won; Choi, Hongyoon; Jang, Su Chul; Yoo, Min Young; Park, Ji Yong; Choi, Na Eun; Oh, Hyun Jeong; Ha, Seunggyun; Lee, Yun-Sang; Jeong, Jae Min; Gho, Yong Song; Lee, Dong Soo

    2015-01-01

    Exosomes known as nano-sized extracellular vesicles attracted recent interests due to their potential usefulness in drug delivery. Amid remarkable advances in biomedical applications of exosomes, it is crucial to understand in vivo distribution and behavior of exosomes. Here, we developed a simple method for radiolabeling of macrophage-derived exosome-mimetic nanovesicles (ENVs) with 99mTc-HMPAO under physiologic conditions and monitored in vivo distribution of 99mTc-HMPAO-ENVs using SPECT/CT in living mice. ENVs were produced from the mouse RAW264.7 macrophage cell line and labeled with 99mTc-HMPAO for 1 hr incubation, followed by removal of free 99mTc-HMPAO. SPECT/CT images were serially acquired after intravenous injection to BALB/c mouse. When ENVs were labeled with 99mTc-HMPAO, the radiochemical purity of 99mTc-HMPAO-ENVs was higher than 90% and the expression of exosome specific protein (CD63) did not change in 99mTc-HMPAO-ENVs. 99mTc-HMPAO-ENVs showed high serum stability (90%) which was similar to that in phosphate buffered saline until 5 hr. SPECT/CT images of the mice injected with 99mTc-HMPAO-ENVs exhibited higher uptake in liver and no uptake in brain, whereas mice injected with 99mTc-HMPAO showed high brain uptake until 5 hr. Our noninvasive imaging of radiolabeled-ENVs promises better understanding of the in vivo behavior of exosomes for upcoming biomedical application. PMID:26497063

  2. Human anti-murine immune response following administration of radiolabeled monoclonal antibodies

    SciTech Connect

    Reynolds, J.C.; Carrasquillo, J.C.; Larson, S.M.

    1985-05-01

    The author's purpose is to measure circulating anti-murine immunoglobulin antibodies (HAMA) in patients who previously received radiolabeled monoclonal antibodies (MoAb) for tumor imaging and therapy. Because the presence of HAMA may negate further use of MoAb in patients, it is important to determine the frequency and rate of HAMA development. Patients received radiolabeled MoAb Fab 96.5 (IgG2a), Fab 48.7 (IgG1), T101 (IgG2a), B72.3 (IgG1), 9.2.27 (IgG2a) and 791T/36 (IgG2b). HAMA was measured by incubating I-125 labeled 96.5, 48.7 or B72.3 with serum and isolating human IgG with Staphyloccocal protein A cells by centrifugation. The assays were capable of detecting HAMA concentrations which bound 20 ng/ml of monoclonal antibody. 12 of 37 patients who received IgG developed HAMA within 4 months of a single injection. For one patient this occurred as early as 1 week post injection. 2 of 18 patients who received Fab developed HAMA. One of these patients received multiple injections of MoAb. 2 of 3 patients who received IgG2B were positive for HAMA. There was no apparent difference in the positive HAMA when antibody or fragment was given SubQ or IV. The authors conclude that the use of IgG MoAb are more likely to lead to the development of antimurine immunoglobulin antibodies.

  3. Cold, Gas-Phase UV and IR Spectroscopy of Protonated Leucine Enkephalin and its Analogues

    NASA Astrophysics Data System (ADS)

    Burke, Nicole L.; Redwine, James; Dean, Jacob C.; McLuckey, Scott A.; Zwier, Timothy S.

    2014-06-01

    The conformational preferences of peptide backbones and the resulting hydrogen bonding patterns provide critical biochemical information regarding the structure-function relationship of peptides and proteins. The spectroscopic study of cryogenically-cooled peptide ions in a mass spectrometer probes these H-bonding arrangements and provides information regarding the influence of a charge site. Leucine enkephalin, a biologically active endogenous opiod peptide, has been extensively studied as a model peptide in mass spectrometry. This talk will present a study of the UV and IR spectroscopy of protonated leucine enkephalin [YGGFL+H]+ and two of its analogues: the sodiated [YGGFL+Na]+ and C-terminally methyl esterified [YGGFL-OMe+H]+ forms. All experiments were performed in a recently completed multi-stage mass spectrometer outfitted with a cryocooled ion trap. Ions are generated via nano-electrospray ionization and the analyte of interest is isolated in a linear ion trap. The analyte ions are trapped in a 22-pole ion trap held at 5 K by a closed cycle helium cryostat and interrogated via UV and IR lasers. Photofragments are trapped and isolated in a second LIT and mass analyzed. Double-resonance UV and IR methods were used to assign the conformation of [YGGFL+H]+, using the NH/OH stretch, Amide I, and Amide II regions of the infrared spectrum. The assigned structure contains a single backbone conformation at vibrational/rotational temperatures of 10 K held together with multiple H-bonds that self-solvate the NH3+ site. A "proton wire" between the N and C termini reinforces the H-bonding activity of the COO-H group to the F-L peptide bond, whose cleavage results in formation of the b4 ion, which is a prevalent, low-energy fragmentation pathway for [YGGFL+H]+. The reinforced H-bonding network in conjunction with the mobile proton theory may help explain the prevalence of the b4 pathway. In order to elucidate structural changes caused by modifying this H-bonding activity

  4. Multipurpose ligand, DAKLI (Dynorphin A-analogue Kappa LIgand), with high affinity and selectivity for dynorphin (. kappa. opioid) binding sites

    SciTech Connect

    Goldstein, A.; Nestor, J.J. Jr.; Naidu, A.; Newman, S.R. )

    1988-10-01

    The authors describe a synthetic ligand, DALKI (Dynorphin A-analogue Kappa LIgand), related to the opioid peptide dynorphin A. A single reactive amino group at the extended carboxyl terminus permits various reporter groups to be attached, such as {sup 125}I-labeled Bolton-Hunter reagent, fluorescein isothiocyanate, or biotin. These derivatives have high affinity and selectivity for the dynorphin ({kappa} opioid) receptor. An incidental finding is that untreated guinea pig brain membranes have saturable avidin binding sites.

  5. Hyperthermic responses to central injections of some peptide and non-peptide opioids in the guinea-pig

    NASA Technical Reports Server (NTRS)

    Kandasamy, S. B.; Williams, B. A.

    1983-01-01

    The intracerebroventricular administration of prototype nonpeptide opioid receptor (mu, kappa, and sigma) agonists, morphine, ketocyclazocine, and N-allyl normetazocine and an agonist at both kappa and sigma receptors, pentazocine, was found to induce hyperthermia in guinea pigs. The similar administration of peptide opioids like beta endorphin, methionine endkephalin, leucine endkephaline, and several of their synthetic analogues was also found to cause hyperthermia. Only the liver-like transport system of the three anion transport systems (iodide, hippurate, and liver-like) present in the choroid plexus was determined to be important to the central inactivation of beta-endorphin and two synthetic analogues. Prostaglandins and norepinephrine (NE) as well as cAMP were not involved in peptide and nonpeptide opioid-induced hyperthermia. Naloxone-sensitive receptors were found to be involved in the induction of hyperthermia by morphine and beta-endorphin, while hyperthermic responses to ketocyclazocine, N-allyl normetazocine, pentazocine, Met-enkephalin, Leu-enkephalin, and two of the synthetic analogues were not antagonized by nalozone. The lack of antagonism of naloxone on pyrogen, arachidonic acid, PGE2, dibutyryl cAMP, and NE-induced hyperthermia shows that endogenous opioid peptides are not likely to be central mediators of the hyperthermia induced by these agents.

  6. Stapled Vasoactive Intestinal Peptide (VIP) Derivatives Improve VPAC2 Agonism and Glucose-Dependent Insulin Secretion.

    PubMed

    Giordanetto, Fabrizio; Revell, Jefferson D; Knerr, Laurent; Hostettler, Marie; Paunovic, Amalia; Priest, Claire; Janefeldt, Annika; Gill, Adrian

    2013-12-12

    Agonists of vasoactive intestinal peptide receptor 2 (VPAC2) stimulate glucose-dependent insulin secretion, making them attractive candidates for the treatment of hyperglycaemia and type-II diabetes. Vasoactive intestinal peptide (VIP) is an endogenous peptide hormone that potently agonizes VPAC2. However, VIP has a short serum half-life and poor pharmacokinetics in vivo and is susceptible to proteolytic degradation, making its development as a therapeutic agent challenging. Here, we investigated two peptide cyclization strategies, lactamisation and olefin-metathesis stapling, and their effects on VPAC2 agonism, peptide secondary structure, protease stability, and cell membrane permeability. VIP analogues showing significantly enhanced VPAC2 agonist potency, glucose-dependent insulin secretion activity, and increased helical content were discovered; however, neither cyclization strategy appeared to effect proteolytic stability or cell permeability of the resulting peptides.

  7. Tracking deposition of a 14C-radiolabeled kudzu hairy root-derived isoflavone-rich fraction into bone.

    PubMed

    Mun, Jonathan G; Grannan, Michael D; Lachcik, Pamela J; Rogers, Randy B; Yousef, Gad G; Grace, Mary H; Janle, Elsa M; Wu, Qing Li; Simon, James E; Weaver, Connie M; Lila, Mary Ann

    2010-10-01

    Hairy roots were induced in four genotypes from three kudzu species (Pueraria montana var. lobata, P. lobata and P. phaseoloides) in vitro using Agrobacterium rhizogenes to stimulate rapid secondary metabolite synthesis. Hairy roots from P. montana var. lobata (United States Department of Agriculture no. PI 434246) yielded the highest puerarin and total isoflavone content and the greatest new biomass per growth cycle among the genotypes evaluated. Hairy roots from this genotype were selected for radiolabeling using (14)C-sucrose as a carbon source. Isoflavones from radiolabeled kudzu hairy root cultures were extracted with 80% methanol, partitioned by solvent extraction, and then subfractionated by Sephadex LH-20 gel filtration. Radiolabeled isoflavones were isolated in a highly enriched fraction, which contained predominantly puerarin, daidzin and malonyl-daidzin and had an average radioactivity of 8.614 MBq/g (232.8 μCi/g) dry fraction. The (14)C-radiolabeled, isoflavone-rich fraction was orally administered at a dose of 60 mg/kg body weight to male Sprague-Dawley rats implanted with a jugular catheter, a subcutaneous ultrafiltrate probe and a brain microdialysate probe. Serum, interstitial fluid, brain microdialysate, urine and feces were collected using a Culex(®) Automated Blood Collection System for 24 h. At the end of this period, rats were sacrificed and major tissues were collected. Analysis by a scintillation counter confirmed that a bolus dose of (14)C-radiolabeled, isoflavone-rich kudzu fraction reached bone tissues, which accumulated 0.011%, 0.09% and 0.003% of the administered dose in femur, tibia and vertebrae, respectively. Femurs extracted with 80% methanol were analyzed by high-performance liquid chromatography with electrospray ionization-mass spectrometry and were found to contain trace quantities of puerarin, daidzein and puerarin glucuronide. This study demonstrates that kudzu isoflavones and metabolites are capable of reaching bone tissues

  8. Biosynthesis of amidated joining peptide from pro-adrenocorticotropin-endorphin

    SciTech Connect

    Cullen, E.I.; Mains, R.E. )

    1987-09-01

    Joining peptide is the major alpha-amidated product of pro-ACTH/endorphin (PAE) in AtT-20 corticotropic tumor cells. To study intracellular joining peptide synthesis, affinity purified antibodies directed against gamma-MSH, joining peptide, and ACTH were used to immunoprecipitate extracts from biosynthetically labeled AtT-20 cells. Immunoprecipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by tryptic peptide mapping on HPLC. In steady labeling experiments, radioactivity in amidated joining peptide (JP) increased roughly linearly with time, in the manner of a final product, whereas radioactivity associated with PAE (1-94)NH2 reached a constant value after 2-4 h, indicating that PAE(1-94)NH2 is an intermediate in the biosynthesis of JP. Radioactivity appeared in ACTH(1-39) well before JP, consistent with a cleavage order in which ACTH is cleaved from PAE(1-95) before JP sequences are cleaved from PAE(1-74). This conclusion was supported by tryptic peptide analyses of immunoprecipitates, which indicated that less than 5% of JP-related material is cleaved from PAE(1-74) before being cleaved from ACTH-related sequences. After a pulse label, radioactivity in PAE(1-94)NH2 reached a peak value after 1 h of chase and declined with a half-life of less than 1 h. Amidated JP increased to a constant level after 2 h of chase. Enough radiolabeled PAE(1-94)NH2 was detected to account for about half of the radioactivity found in amidated JP, indicating that about half of JP-related material is first cleaved from PAE(1-95) before being amidated. This result was corroborated using HPLC purification to determine both amidated and glycine-extended forms of JP.

  9. Covalent surface chemistry gradients for presenting bioactive peptides.

    PubMed

    Kipper, Matt J; Kleinman, Hynda K; Wang, Francis W

    2007-04-15

    The activation of surfaces by covalent attachment of bioactive moieties is an important strategy for improving the performance of biomedical materials. Such techniques have also been used as tools to study cellular responses to particular chemistries of interest. The creation of gradients of covalently bound chemistries is a logical extension of this technique. Gradient surfaces may permit the rapid screening of a large range of concentrations in a single experiment. In addition, the biological response to the gradient itself may provide new information on receptor requirements and cell signaling. The current work describes a rapid and flexible technique for the covalent addition of bioactive peptide gradients to a surface or gel and a simple fluorescence technique for assaying the gradient. In this technique, bioactive peptides with a terminal cysteine are bound via a heterobifunctional coupling agent to primary amine-containing surfaces and gels. A gradient in the coupling agent is created on the surfaces or gels by varying the residence time of the coupling agent across the surface or gel, thereby controlling the extent of reaction. We demonstrate this technique using poly(l-lysine)-coated glass surfaces and fibrin gels. Once the surface or gel has been activated by the addition of the coupling agent gradient, the bioactive peptide is added. Quantitation of the gradient is achieved by measuring the reaction kinetics of the coupling agent with the surface or gel of interest. This can be done either by fluorescently labeling the coupling agent (in the case of surfaces) or by spectrophotometrically detecting the release of pyridine-2-thione, which is produced when the thiol-reactive portion of the coupling agent reacts. By these methods, we can obtain reasonably precise estimates for the peptide gradients without using expensive spectroscopic or radiolabeling techniques. Validation with changes in fibroblast cell migration behavior across a bioactive peptide

  10. Radiolabeled Escherichia coli heat-stable enterotoxin analogs for in vivo imaging of colorectal cancer

    NASA Astrophysics Data System (ADS)

    Giblin, M. F.; Sieckman, G. L.; Owen, N. K.; Hoffman, T. J.; Forte, L. R.; Volkert, W. A.

    2005-12-01

    The human Escherichia coli heat-stable enterotoxin (STh, amino acid sequence N1SSNYCCELCCNPACTGCY19) binds specifically to the guanylate cyclase C (GC-C) receptor, which is present in high density on the apical surface of normal intestinal epithelial cells as well as on the surface of human colon cancer cells. In the current study, two STh analogs were synthesized and evaluated in vitro and in vivo. Both analogs shared identical 6-19 core sequences, and had N-terminal pendant DOTA moieties. The analogs differed in the identity of a 6 amino acid peptide sequence intervening between DOTA and the 6-19 core. In one analog, the peptide was an RGD-containing sequence found in human fibronectin (GRGDSP), while in the other this peptide sequence was randomly scrambled (GRDSGP). The results indicated that the presence of the human fibronectin sequence in the hybrid peptide did not affect tumor localization in vivo.

  11. On the mechanical analogue of DNA.

    PubMed

    Yakushevich, Ludmila

    2017-03-01

    The creation of mechanical analogues of biological systems is known as a useful instrument that helps to understand better the dynamical mechanisms of the functioning of living organisms. Mechanical analogues of biomolecules are usually constructed for imitation of their internal mobility, which is one of the most important properties of the molecules. Among the different types of internal motions, angular oscillations of nitrous bases are of special interest because they make a substantial contribution to the base pairs opening that in turn is an important element of the process of the DNA-protein recognition. In this paper, we investigate the possibility to construct a mechanical analogue for imitation of angular oscillations of nitrous bases in inhomogeneous DNA. It is shown that the analogue has the form of a mechanical chain of non-identical pendulums that oscillate in the gravitational field of the Earth and coupled by identical springs. The masses and lengths of pendulums, as well as the distances between neighboring pendulums and the rigidity of springs are calculated. To illustrate the approach, we present the result of construction of the mechanical analogue of the fragment of the sequence of bacteriophage T7D.

  12. Analogue Downscaling of Seasonal Rainfall Forecasts

    NASA Astrophysics Data System (ADS)

    Charles, A. N.; Timbal, B.; Hendon, H.

    2010-12-01

    We have taken an existing statistical downscaling model (SDM), based on meteorological analogues that was developed for downscaling climate change projections (Timbal et al 2009), and applied it in the seasonal forecasting context to produce downscaled rainfall hindcasts from a coupled model seasonal forecast system (POAMA). Downscaling of POAMA forecasts is required to provide seasonal climate information at local scales of interest. Analogue downscaling is a simple technique to generate rainfall forecasts appropriate to the local scale by conditioning on the large scale predicted GCM circulation and the local topography and climate. Analogue methods are flexible and have been shown to produce good results when downscaling 20th century South Eastern Australian rainfall output from climate models. A set of re-forecasts for three month rainfall at 170 observing stations in the South Murray Darling region of Australia were generated using predictors from the POAMA re-forecasts as input for the analogue SDM. The predictors were optimised over a number of different GCMS in previous climate change downscaling studies. Downscaling with the analogue SDM results in predicted rainfall with realistic variance while maintaining the modest predictive skill of the dynamical model. Evaluation of the consistency between the large scale mean of downscaled and direct GCM output precipitation is encouraging.

  13. Turn structures in CGRP C-terminal analogues promote stable arrangements of key residue side chains.

    PubMed

    Carpenter, K A; Schmidt, R; von Mentzer, B; Haglund, U; Roberts, E; Walpole, C

    2001-07-27

    The 37-amino acid calcitonin gene-related peptide (CGRP) is a potent endogenous vasodilator thought to be implicated in the genesis of migraine attack. CGRP antagonists may thus have therapeutic value for the treatment of migraine. The CGRP C-terminally derived peptide [D(31),P(34),F(35)]CGRP(27-37)-NH(2) was recently identified as a high-affinity hCGRP(1) receptor selective antagonist. Reasonable CGRP(1) affinity has also been demonstrated for several related analogues, including [D(31),A(34),F(35)]CGRP(27-37)-NH(2). In the study presented here, conformational and structural features in CGRP(27-37)-NH(2) analogues that are important for hCGRP(1) receptor binding were explored. Structure-activity studies carried out on [D(31),P(34),F(35)]CGRP(27-37)-NH(2) resulted in [D(31),P(34),F(35)]CGRP(30-37)-NH(2), the shortest reported CGRP C-terminal peptide analogue exhibiting reasonable hCGRP(1) receptor affinity (K(i) = 29.6 nM). Further removal of T(30) from the peptide's N-terminus greatly reduced receptor affinity from the nanomolar to micromolar range. Additional residues deemed critical for hCGRP(1) receptor binding were identified from an alanine scan of [A(34),F(35)]CGRP(28-37)-NH(2) and included V(32) and F(37). Replacement of the C-terminal amide in this same peptide with a carboxyl, furthermore, resulted in a greater than 50-fold reduction in hCGRP(1) affinity, thus suggesting a direct role for the amide moiety in receptor binding. The conformational properties of two classes of CGRP(27-37)-NH(2) peptides, [D(31),X(34),F(35)]CGRP(27-37)-NH(2) (X is A or P), were examined by NMR spectroscopy and molecular modeling. A beta-turn centered on P(29) was a notable feature consistently observed among active peptides in both series. This turn led to exposure of the critical T(30) residue to the surrounding environment. Peptides in the A(34) series were additionally characterized by a stable C-terminal helical turn that resulted in the three important residues (T(30), V

  14. Peptide Antimicrobial Agents

    PubMed Central

    Jenssen, Håvard; Hamill, Pamela; Hancock, Robert E. W.

    2006-01-01

    Antimicrobial host defense peptides are produced by all complex organisms as well as some microbes and have diverse and complex antimicrobial activities. Collectively these peptides demonstrate a broad range of antiviral and antibacterial activities and modes of action, and it is important to distinguish between direct microbicidal and indirect activities against such pathogens. The structural requirements of peptides for antiviral and antibacterial activities are evaluated in light of the diverse set of primary and secondary structures described for host defense peptides. Peptides with antifungal and antiparasitic activities are discussed in less detail, although the broad-spectrum activities of such peptides indicate that they are important host defense molecules. Knowledge regarding the relationship between peptide structure and function as well as their mechanism of action is being applied in the design of antimicrobial peptide variants as potential novel therapeutic agents. PMID:16847082

  15. Immunomodulatory effects of a set of amygdalin analogues on human keratinocyte cells.

    PubMed

    Baroni, A; Paoletti, I; Greco, R; Satriano, R A; Ruocco, E; Tufano, M A; Perez, J J

    2005-11-01

    Peptide T (PT) is an octapeptide shown to resolve psoriatic lesions. Our previous investigations suggest that keratinocytes play an important role in conditioning the therapeutic effects of the PT in psoriasis. However, peptides are not good therapeutic agents, because they exhibit poor absorption, are easily metabolized and are immunogenic. Using computational methods, the natural product amygdalin was identified as peptidomimetic of PT. However, amygdalin exhibits a toxic profile due to its cyanide group. To overcome this deleterious effect, we synthesized analogues lacking the cyanide group. Human keratinocytes were treated with PT or with three different peptidomimetics of PT. To study its effects on the expression of HSP-70, TGF-beta, alpha-v integrin, ICAM-1 and cytokines, we analysed the protein levels by Western blot and ELISA. Our results show that the different peptidomimetics of PT tested exhibit a similar biological behaviour in regard to the overexpression of HSP-70, TGF-beta and alpha-v integrin than the native peptide. TNF-alpha is overexpressed by PT and SVT-03018; between the other two analogs, SVT-03016 do not produce any significant change in regard to the control, while SVT-03017 shows only a moderate increase in regard to control. SVT-03018 provokes a remarkable upregulation of IL-10, stronger than SVT-03016, SVT-03017 and PT. All the other three analogues reduce comparably to the PT, the expression of ICAM-1 and do not increase the release of proinflammatory cytokines. The results highlighted that the three analogues of amygdalin with the cyanide group removed exhibit the same biological effects of PT. Therefore, they can be considered peptidomimetics, suggesting their possible use in the treatment of psoriasis.

  16. Sequence-activity relationship, and mechanism of action of mastoparan analogues against extended-drug resistant Acinetobacter baumannii.

    PubMed

    Vila-Farrés, Xavier; López-Rojas, Rafael; Pachón-Ibáñez, Maria Eugenia; Teixidó, Meritxell; Pachón, Jerónimo; Vila, Jordi; Giralt, Ernest

    2015-08-28

    The treatment of some infectious diseases can currently be very challenging since the spread of multi-, extended- or pan-resistant bacteria has considerably increased over time. On the other hand, the number of new antibiotics approved by the FDA has decreased drastically over the last 30 years. The main objective of this study was to investigate the activity of wasp peptides, specifically mastoparan and some of its derivatives against extended-resistant Acinetobacter baumannii. We optimized the stability of mastoparan in human serum since the specie obtained after the action of the enzymes present in human serum is not active. Thus, 10 derivatives of mastoparan were synthetized. Mastoparan analogues (guanidilated at the N-terminal, enantiomeric version and mastoparan with an extra positive charge at the C-terminal) showed the same activity against Acinetobacter baumannii as the original peptide (2.7 μM) and maintained their stability to more than 24 h in the presence of human serum compared to the original compound. The mechanism of action of all the peptides was carried out using a leakage assay. It was shown that mastoparan and the abovementioned analogues were those that released more carboxyfluorescein. In addition, the effect of mastoparan and its enantiomer against A. baumannii was studied using transmission electron microscopy (TEM). These results suggested that several analogues of mastoparan could be good candidates in the battle against highly resistant A. baumannii infections since they showed good activity and high stability.

  17. New proctolin analogues and their myotropic effects on heart of yellow mealworm Tenebrio molitor L. and foregut of locust-Schistocerca gregaria L.

    PubMed

    Kuczer, M; Rosiński, G; Issberner, J; Osborne, R; Konopińska, D

    1998-01-01

    We have extended our work on structure/activity relationship of neuropeptide proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH) by evaluating the effects of the following proctolin analogues: H-X1-Tyr-Leu-Pro-Thr-OH, where X1 = D-Arg (1), N-Me-Arg (2), Can (3), D-Tyr2, D-Leu3, D-Thr5]-proctolin (12). In analogues 1-9, the N-terminal Arg-residue was replaced by basic amino acid derivatives with peptides containing amino acid residues with an isosteric system on the back side chain relative to Arg (compounds 3, 5 and 6) or homo-Arg (compound 7). Analogues 1-12 were evaluated for myotropic action on in vitro heart preparation of Tenebrio molitor, whereas peptides 2, 5 and 7-12 were tested for contractile action on isolated foregut of Schistocerca gregaria. Peptides 2 and 3 retained full cardiotropic activity in Tenebrio molitor while peptides 5 and 7 preserved 40% and 15%, respectively, locust-gut contracting activity of proctolin. Peptides 11 and 12 showed antagonistic activity in Schistocerca gregaria foregut.

  18. Novel short antibacterial and antifungal peptides with low cytotoxicity: Efficacy and action mechanisms

    SciTech Connect

    Qi, Xiaobao; Zhou, Chuncai; Li, Peng; Xu, Weixin; Cao, Ye; Ling, Hua; Ning Chen, Wei; Ming Li, Chang; Xu, Rong; Lamrani, Mouad; Mu, Yuguang; Leong, Susanna Su Jan; Wook Chang, Matthew; Chan-Park, Mary B.

    2010-07-30

    Research highlights: {yields} Short antimicrobial peptides with nine and eleven residues were developed. {yields} These peptides show strong bactericidal activity against clinically important bacterial and fungal pathogens. {yields} These peptides exhibit high stability in the presence of salts, and low cytotoxicity. {yields} These peptides exert their action by disrupting membrane lipids. -- Abstract: Short antimicrobial peptides with nine and eleven residues were developed against several clinically important bacterial and fungal pathogens (specifically Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Fusarium solani). Twelve analogues of previously reported peptides BP76 (KKLFKKILKFL) and Pac-525 (KWRRWVRWI) were designed, synthesized, and tested for their antimicrobial activities. Two of our eleven amino acid peptides, P11-5 (GKLFKKILKIL) and P11-6 (KKLIKKILKIL), have very low MICs of 3.1-12.5 {mu}g ml{sup -1} against all five pathogens. The MICs of these two peptides against S. aureus, C. albicans and F. solani are four to ten times lower than the corresponding MICs of the reference peptide BP76. P9-4 (KWRRWIRWL), our newly designed nine-amino acid analogue, also has particularly low MICs of 3.1-6.2 {mu}g ml{sup -1} against four of the tested pathogens; these MICs are two to eight times lower than those reported for Pac-525 (6.2-50 {mu}g ml{sup -1}).These new peptides (P11-5, P11-6 and P9-4) also exhibit improved stability in the presence of salts, and have low cytotoxicity as shown by the hemolysis and MTT assays. From the results of field-emission scanning electron microscopy, membrane depolarization and dye-leakage assays, we propose that these peptides exert their action by disrupting membrane lipids. Molecular dynamics simulation studies confirm that P11-6 peptide maintains relatively stable helical structure and exerts more perturbation action on the order of acyl tail of lipid bilayer.

  19. Antimicrobial Peptides in 2014

    PubMed Central

    Wang, Guangshun; Mishra, Biswajit; Lau, Kyle; Lushnikova, Tamara; Golla, Radha; Wang, Xiuqing

    2015-01-01

    This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms. PMID:25806720

  20. PH dependent adhesive peptides

    SciTech Connect

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  1. GABAA Receptor Modulation by Etomidate Analogues

    PubMed Central

    Pejo, Ervin; Santer, Peter; Wang, Lei; Dershwitz, Philip; Husain, S. Shaukat; Raines, Douglas E.

    2015-01-01

    Background Etomidate is a highly potent anesthetic agent that is believed to produce hypnosis by enhancing γ-aminobutyric acid type A (GABAA) receptor function. We characterized the GABAA receptor and hypnotic potencies of etomidate analogues. We then used computational techniques to build statistical and graphical models that relate the potencies of these etomidate analogues to their structures in order to identify the specific molecular determinants of potency. Methods GABAA receptor potencies were defined with voltage-clamp electrophysiology using α1β3γ2 receptors harboring a channel mutation (α1(L264T)) that enhances anesthetic sensitivity (n = 36 – 60 measurements per concentration-response curve). The hypnotic potencies of etomidate analogues were defined using a loss of righting reflexes assay in Sprague Dawley rats (n = 9 – 21 measurements per dose-response curve). Three-dimensional quantitative structure-activity relationships were determined in silico using comparative molecular field analysis. Results The GABAA receptor and hypnotic potencies of etomidate and the etomidate analogues ranged by 91-fold and 53-fold, respectively. These potency measurements were significantly correlated (r2 = 0.72), but neither measurement correlated with drug hydrophobicity (r2 = 0.019 and 0.005, respectively). Statistically significant and predictive comparative molecular field analysis models were generated and a pharmacophore model was built that revealed both the structural elements in etomidate analogues associated with high potency and the interactions that these elements make with the etomidate binding site. Conclusion There are multiple specific structural elements in etomidate and etomidate analogues that mediate GABAA receptor modulation. Modifying any one element can alter receptor potency by an order of magnitude or more. PMID:26691905

  2. Classical Simulated Annealing Using Quantum Analogues

    NASA Astrophysics Data System (ADS)

    La Cour, Brian R.; Troupe, James E.; Mark, Hans M.

    2016-08-01

    In this paper we consider the use of certain classical analogues to quantum tunneling behavior to improve the performance of simulated annealing on a discrete spin system of the general Ising form. Specifically, we consider the use of multiple simultaneous spin flips at each annealing step as an analogue to quantum spin coherence as well as modifications of the Boltzmann acceptance probability to mimic quantum tunneling. We find that the use of multiple spin flips can indeed be advantageous under certain annealing schedules, but only for long anneal times.

  3. Insulin analogues: action profiles beyond glycaemic control.

    PubMed

    Eckardt, Kristin; Eckel, Jürgen

    2008-02-01

    A variety of studies have documented significant improvements in the treatment of type 1 and 2 diabetes after the introduction of artificial insulins. This review gives an overview of insulin analogues which are currently approved for therapeutical use. Clinical data regarding the efficiency to control blood glucose level as well as improving HbA1c level in comparison to conventional insulin preparations in type 1 and 2 diabetic patients are summarized. Furthermore, special features of insulin analogues regarding their signalling properties are discussed with focus on the proliferative effects of insulin glargine as well as some recent data of insulin detemir.

  4. Delivery of peptides to the blood and brain after oral uptake of quaternary ammonium palmitoyl glycol chitosan nanoparticles.

    PubMed

    Lalatsa, A; Garrett, N L; Ferrarelli, T; Moger, J; Schätzlein, A G; Uchegbu, I F

    2012-06-04

    The clinical development of therapeutic peptides has been restricted to peptides for non-CNS diseases and parenteral dosage forms due to the poor permeation of peptides across the gastrointestinal mucosa and the blood-brain barrier. Quaternary ammonium palmitoyl glycol chitosan (GCPQ) nanoparticles facilitate the brain delivery of orally administered peptides such as leucine(5)-enkephalin, and here we examine the mechanism of GCPQ facilitated oral peptide absorption and brain delivery. By analyzing the oral biodistribution of radiolabeled GCPQ nanoparticles, the oral biodistribution of the model peptide leucine(5)-enkephalin and coherent anti-Stokes Raman scattering microscopy tissue images after an oral dose of deuterated GCPQ nanoparticles, we have established a number of facts. Although 85-90% of orally administered GCPQ nanoparticles are not absorbed from the gastrointestinal tract, a peak level of 2-3% of the oral GCPQ dose is detected in the blood 30 min after dosing, and these GCPQ particles appear to transport the peptides to the blood. Additionally, although peptide loaded nanoparticles from low (6 kDa) and high (50 kDa) molecular weight GCPQ are taken up by enterocytes, polymer particles with a polymer molecular weight greater than 6 kDa are required to facilitate peptide delivery to the brain after oral administration. By examining our current and previous data, we conclude that GCPQ particles facilitate oral peptide absorption by protecting the peptide from gastrointestinal degradation, adhering to the mucus to increase the drug gut residence time and transporting GCPQ associated peptide across the enterocytes and to the systemic circulation, enabling the GCPQ stabilized peptide to be transported to the brain. Orally administered GCPQ particles are also circulated from the gastrointestinal tract to the liver and onward to the gall bladder, presumably for final transport back to the gastrointestinal tract.

  5. Preclinical Validation of the Heparin-Reactive Peptide p5+14 as a Molecular Imaging Agent for Visceral Amyloidosis

    PubMed Central

    Wall, Jonathan S.; Martin, Emily B.; Richey, Tina; Stuckey, Alan C.; Macy, Sallie; Wooliver, Craig; Williams, Angela; Foster, James S.; McWilliams-Koeppen, Penney; Uberbacher, Ed; Cheng, Xiaolin; Kennel, Stephen J.

    2015-01-01

    Amyloid is a complex pathologic matrix comprised principally of paracrystalline protein fibrils and heparan sulfate proteoglycans. Systemic amyloid diseases are rare, thus, routine diagnosis is often challenging. The glycosaminoglycans ubiquitously present in amyloid deposits are biochemically and electrochemically distinct from those found in the healthy tissues due to the high degree of sulfation. We have exploited this unique property and evaluated heparin-reactive peptides, such as p5+14, as novel agents for specifically targeting and imaging amyloid. Herein, we demonstrate that radiolabeled p5+14 effectively bound murine AA amyloid in vivo by using molecular imaging. Biotinylated peptide also reacted with the major forms of human amyloid in tissue sections as evidenced immunohistochemically. Furthermore, we have demonstrated that the peptide also binds synthetic amyloid fibrils that lack glycosaminoglycans implying that the dense anionic motif present on heparin is mimicked by the amyloid protein fibril itself. These biochemical and functional data support the translation of radiolabeled peptide p5+14 for the clinical imaging of amyloid in patients. PMID:25923515

  6. Preclinical Validation of the Heparin-Reactive Peptide p5+14 as a Molecular Imaging Agent for Visceral Amyloidosis.

    PubMed

    Wall, Jonathan S; Martin, Emily B; Richey, Tina; Stuckey, Alan C; Macy, Sallie; Wooliver, Craig; Williams, Angela; Foster, James S; McWilliams-Koeppen, Penney; Uberbacher, Ed; Cheng, Xiaolin; Kennel, Stephen J

    2015-04-27

    Amyloid is a complex pathologic matrix comprised principally of paracrystalline protein fibrils and heparan sulfate proteoglycans. Systemic amyloid diseases are rare, thus, routine diagnosis is often challenging. The glycosaminoglycans ubiquitously present in amyloid deposits are biochemically and electrochemically distinct from those found in the healthy tissues due to the high degree of sulfation. We have exploited this unique property and evaluated heparin-reactive peptides, such as p5+14, as novel agents for specifically targeting and imaging amyloid. Herein, we demonstrate that radiolabeled p5+14 effectively bound murine AA amyloid in vivo by using molecular imaging. Biotinylated peptide also reacted with the major forms of human amyloid in tissue sections as evidenced immunohistochemically. Furthermore, we have demonstrated that the peptide also binds synthetic amyloid fibrils that lack glycosaminoglycans implying that the dense anionic motif present on heparin is mimicked by the amyloid protein fibril itself. These biochemical and functional data support the translation of radiolabeled peptide p5+14 for the clinical imaging of amyloid in patients.

  7. MULTIVALENT DISPLAY OF PENDANT PRO-APOPTOTIC PEPTIDES INCREASES CYTOTOXIC ACTIVITY

    PubMed Central

    Chu, David S.H.; Bocek, Michael J.; Shi, Julie; Ta, Anh; Ngambenjawong, Chayanon; Rostomily, Robert C.; Pun, Suzie H.

    2015-01-01

    Several cationic antimicrobial peptides have been investigated as potential anti-cancer drugs due to their demonstrated selective toxicity towards cancer cells relative to normal cells. For example, intracellular delivery of KLA, a pro-apoptotic peptide, results in toxicity against a variety of cancer cell lines; however, the relatively low activity and small size leads to rapid renal excretion when applied in vivo, limiting its therapeutic potential. In this work, apoptotic peptide-polymer hybrid materials were developed to increase apoptotic peptide activity via multivalent display. Multivalent peptide materials were prepared with comb-like structure by RAFT copolymerization of peptide macromonomers with N-(2-hydroxypropyl) methacrylamide (HPMA). Polymers displayed a GKRK peptide sequence for targeting p32, a protein often overexpressed on the surface of cancer cells, either fused with or as a comonomer to a KLA macromonomer. In three tested cancer cell lines, apoptotic polymers were significantly more cytotoxic than free peptides as evidenced by an order of magnitude decrease in IC50 values for the polymers compared to free peptide. The uptake efficiency and intracellular trafficking of one polymer construct was determined by radiolabeling and subcellular fractionation. Despite their more potent cytotoxic profile, polymeric KLA constructs have poor cellular uptake efficiency (<1%). A significant fraction (20%) of internalized constructs localize with intact mitochondrial fractions. In an effort to increase cellular uptake, polymer amines were converted to guanidines by reaction with O-methylisourea. Guanidinylated polymers disrupted function of isolated mitochondria more than their lysine-based analogs, but overall toxicity was decreased, likely due to inefficient mitochondrial trafficking. Thus, while multivalent KLA polymers are more potent than KLA peptides, these materials can be substantially improved by designing next generation materials with improved

  8. Cyclotron production of cesium radionuclides as analogues for francium-221 biodistribution

    NASA Astrophysics Data System (ADS)

    Finn, R.; McDevitt, M.; Sheh, Y.; Lom, C.; Qiao, J.; Cai, S.; Burnazi, E.; Nacca, A.; Pillarsetty, N.; Jaggi, J.; Scheinberg, D.

    2005-12-01

    In our clinical investigations focussing on improved therapeutic treatment of specific tumors we have concentrated on a targeted therapy approach utilizing designed radiolabeled monoclonal antibodies as the cytotoxic reagent. The physical characteristics of the alpha particle emitting radionuclide bismuth-213 including the short half-life of 45.6 min, has shown promise for the treatment of specific cancers such as leukemias and lymphomas or micrometastatic carcinomas. In an effort to increase the cytocidal effect of the HuM195, a humanized monoclonal antibody carrier to the CD33 antigen expressed on leukemia cells, our focus is directed toward an "internal" nano-generator composed of Ac-225 radionuclide, the parent of the bismuth-213. The actinium-225 radionuclide decays through several short-lived, alpha emitting daughters including francium-221, astatine-217 and bismuth-213. In order to study the biodistribution and the pharmacokinetics of the individual daughter nuclide, francium-221, the cyclotron production and separation of cesium radionuclides, specifically cesium-132, from a natural xenon gas target was undertaken. The choice of cesium as an analogue for francium was predicated upon both elements being in Group 1A alkali metals and cesium radionuclide possesses a sufficient half-life to allow biodistribution studies to be performed. The preliminary experimental results of this investigation are presented.

  9. Synthesis and characterization of iodobenzamide analogues: Potential D-2 dopamine receptor imaging agents

    SciTech Connect

    Murphy, R.A.; Kung, H.F.; Kung, M.P.; Billings, J. )

    1990-01-01

    (S)-N-((1-Ethyl-2-pyrrolidinyl)methyl)-2-hydroxy-3-iodo-6- methoxybenzamide (({sup 123}I)IBZM) is a central nervous system (CNS) D-2 dopamine receptor imaging agent. In order to investigate the versatility of this parent structure in specific dopamine receptor localization and the potential for developing new dopamine receptor imaging agents, a series of new iodinated benzamides with fused ring systems, naphthalene (INAP) and benzofuran (IBF), was synthesized and radiolabeled, and the in vivo and in vitro biological properties were characterized. The best analogue of IBZM is IBF (21). The specific binding of ({sup 125}I)IBF (21) with rat striatal tissue preparation was found to be saturable and displayed a Kd of 0.106 {plus minus} 0.015 nM. Competition data of various receptor ligands for ({sup 125}I)IBF (21) binding show the following rank order of potency: spiperone greater than IBF (21) greater than IBZM greater than (+)-butaclamol greater than ({plus minus})-ADTN,6,7 greater than ketanserin greater than SCH-23390 much greater than propranolol. The in vivo biodistribution results confirm that ({sup 125}I)IBF (21) concentrated in the striatal area after iv injection into rats. The study demonstrates that ({sup 123}I)IBF (21) is a potential agent for imaging CNS D-2 dopamine receptors.

  10. Recombinant Complement Receptor 2 Radiolabeled with [99mTc(CO)3]+ : A Potential New Radiopharmaceutical for Imaging Activated Complement

    PubMed Central

    McDonnell, James M.; Yahya, Norhakim; Thakor, David; Razavi, Reza; Smith, Richard; Sacks, Steven; Mullen, Gregory E. D.

    2011-01-01

    We describe the design and synthesis of a new Tc-99m labeled bioconjugate for imaging activated complement, based on Short Consensus Repeats 1 and 2 of Complement Receptor 2 (CR2), the binding domain for C3d. To avoid non specific modification of CR2 and the potential for modifying lysine residues critical to the CR2/C3d contact surface, we engineered a new protein, recombinant CR2 (rCR2), to include the C-terminal sequence VFPLECHHHHHH, a hexahistidine tag (for site-specific radiolabeling with [99mTc(CO)3(OH2)3]+). The protein was characterized by N-terminal sequencing, SDS-PAGE and size exclusion chromatography. To test the function of the recombinant CR2, binding to C3d was confirmed by enzyme-linked immunosorbent assay (ELISA). The function was further confirmed by binding of rCR2 to C3d+ red blood cells (RBC) which were generated by deposition of human or rat C3d and analyzed by fluorescence microscopy and flow cytometry. The affinity of rCR2 for C3d+, in presence of 150 mM NaCl, was measured using surface plasma resonance giving rise to a KD≈500 nM. Radiolabeling of rCR2 or an inactive mutant of rCR2 (K41E CR2) or an unrelated protein of a similar size (C2A) with [99mTc(CO)3(OH2)3]+ at gave radiochemical yields >95%. Site-specifically radiolabeled rCR2 bound to C3d to C3d+ RBC. Binding of radiolabeled rCR2 to C3d was inhibited by anti-C3d and the radiolabeled inactive mutant K41E CR2 and C2A did not bind to C3d+ RBCs. We conclude that rCR2-Tc99m has excellent radiolabeling, stability and C3d binding characteristics and warrants in vivo evaluation as an activated complement imaging agent. PMID:21494666

  11. Synthesis of N-glyoxylyl peptides and their in vitro evaluation as HIV-1 protease inhibitors.

    PubMed

    Qasmi, D; de Rosny, E; René, L; Badet, B; Vergely, I; Boggetto, N; Reboud-Ravaux, M

    1997-04-01

    A series of novel synthetic peptides containing an N-terminal glyoxylyl function (CHOCO-) have been tested as inhibitors of HIV-1 protease. The N-glyoxylyl peptide CHOCO-Pro-Ile-Val-NH2, which fulfills the specificity requirements of the MA/CA protease cleavage site together with the criteria of transition state analogue of the catalyzed reaction, was found to be a moderate competitive inhibitor although favorable interactions were visualized between its hydrated form and the catalytic aspartates using molecular modeling. Increasing the length of the peptide sequence led to compounds acting only as substrates.

  12. A switchable stapled peptide.

    PubMed

    Kalistratova, Aleksandra; Legrand, Baptiste; Verdié, Pascal; Naydenova, Emilia; Amblard, Muriel; Martinez, Jean; Subra, Gilles

    2016-03-01

    The O-N acyl transfer reaction has gained significant popularity in peptide and medicinal chemistry. This reaction has been successfully applied to the synthesis of difficult sequence-containing peptides, cyclic peptides, epimerization-free fragment coupling and more recently, to switchable peptide polymers. Herein, we describe a related strategy to facilitate the synthesis and purification of a hydrophobic stapled peptide. The staple consists of a serine linked through an amide bond formed from its carboxylic acid function and the side chain amino group of diaminopropionic acid and through an ester bond formed from its amino group and the side chain carboxylic acid function of aspartic acid. The α-amino group of serine was protonated during purification. Interestingly, when the peptide was placed at physiological pH, the free amino group initiated the O-N shift reducing the staple length by one atom, leading to a more hydrophobic stapled peptide.

  13. Neurotrophic ACTH4-9 analogue therapy normalizes electroencephalographic alterations in chronic experimental allergic encephalomyelitis.

    PubMed

    Duckers, H J; van Dokkum, R P; Verhaagen, J; van Luijtelaar, E L; Coenen, A M; Lopes da Silva, F H; Gispen, W H

    1998-12-01

    Chronic experimental allergic encephalomyelitis (CEAE) is an established experimental model for multiple sclerosis (MS). The demyelinating lesions in the white matter of the central nervous system observed in CEAE and in MS are accompanied by various neurophysiological alterations. Among the best defined electrophysiological abnormalities are the changes in event-related potentials, in particular evoked potentials involving the spinal cord, i.e. motor and sensory evoked potentials. Less familiar are the changes observed in the electroencephalogram of CEAE-affected animals, which are also encountered in the human equivalent, MS. In the present experiment we evaluated the therapeutic value of a neurotrophic peptide treatment [H-Met(O2)-Glu-His-Phe-D-Lys-Phe-OH, an ACTH4-9 analogue] and its effect on the delayed flash visual evoked potentials (VEP) and power spectra of the electroencephalogram, during a 17-week follow-up of CEAE. CEAE animals treated with the neurotrophic peptide were protected against the development of neurological symptoms during the course of the demyelinating syndrome. VEPs of animals suffering from CEAE showed a delay of the latencies of the late components which was significantly counteracted by peptide treatment. The peak-to-peak amplitude of the VEP afterdischarge recorded from CEAE animals was significantly increased during the course of CEAE and correlated closely with the progression of the myelinopathy. Furthermore, CEAE animals showed an increase of electroencephalogram (EEG) beta activity of up to 500% as compared with the age-matched control group. This increase in beta power mainly consisted of a prevailing 20-21 Hz peak, a frequency that normally is not dominant in control EEG recordings of the rat during passive wakefulness. All these electrophysiological phenomena were absent in ACTH4-9 analogue-treated animals. The present findings underscore the potential importance of a neurotrophic peptide treatment in the pharmacotherapy of

  14. Evaluation of bone targeting salmon calcitonin analogues in rats developing osteoporosis and adjuvant arthritis.

    PubMed

    Bhandari, Krishna H; Asghar, Waheed; Newa, Madhuri; Jamali, Fakhreddin; Doschak, Michael R

    2015-01-01

    Synthetic analogues of the peptide hormone calcitonin have been used in medicine as biologic drug therapies for decades, to treat pathological conditions of excessive bone turnover, such as osteoporosis, where more bones are removed than replaced during bone remodeling. Osteoporosis and other chronic skeletal diseases, including inflammatory arthritis, exact a substantial and growing toll on aging populations worldwide however they respond poor to synthetic biologic drug therapy, due in part to the rapid half-life of elimination, which for calcitonin is 43 minutes. To address those shortcomings, we have developed and synthesized bone-targeting variants of calcitonin as a targeted drug delivery strategy, by conjugation to bisphosphonate drug bone-seeking functional groups in highly specific reaction conditions. To evaluate their in vivo efficacy, bisphosphonate-mediated bone targeting with PEGylated (polyethylene glycol conjugated) and non-PEGylated salmon calcitonin analogues were synthesized and dose escalation was performed in female rats developing Osteoporosis. The bone-targeting calcitonin analogues were also tested in a separate cohort of male rats developing adjuvant-induced arthritis. Ovariectomized female rats developing Osteoporosis were administered daily sub-cutaneous injection of analogues equivalent to 5, 10 and 20 IU/kg of calcitonin for 3 months. Adjuvant arthritis was developed in male rats by administering Mycobacterium butyricum through tail base injection. Daily sub-cutaneous injection of analogues equivalent to 20 IU/kg of calcitonin was administered and the rats were measured for visible signs of inflammation to a 21 day endpoint. In both studies, the effect of drug intervention upon bone volume and bone mineral density (BMD) was assessed by measuring the trabecular bone volume percentage and BMD at the proximal tibial metaphysis using in vivo micro-computed tomography. With dose escalation studies, only bone targeting analogue dosed groups

  15. Dumb holes: analogues for black holes.

    PubMed

    Unruh, W G

    2008-08-28

    The use of sonic analogues to black and white holes, called dumb or deaf holes, to understand the particle production by black holes is reviewed. The results suggest that the black hole particle production is a low-frequency and low-wavenumber process.

  16. CO2 Capture with Enzyme Synthetic Analogue

    SciTech Connect

    Cordatos, Harry

    2010-03-01

    Project overview provides background on carbonic anhydrase transport mechanism for CO2 in the human body and proposed approach for ARPA-E project to create a synthetic enzyme analogue and utilize it in a membrane for CO2 capture from flue gas.

  17. Solanapyrone analogues from a Hawaiian fungicolous fungus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four new solanayrone analogues (solanapyrones J-M; 1-4) have been isolated from an unidentified fungicolous fungus collected in Hawaii. The structures and relative configurations of these compounds were determined by analysis of ID NMR, 2D NMR, and MS data. Solanapyrone J(1) showed antifungal acti...

  18. Investigation of the surfactant type and concentration effect on the retention factors of glutathione and its analogues by micellar electrokinetic chromatography.

    PubMed

    Kazarjan, Jana; Mahlapuu, Riina; Hansen, Mats; Soomets, Ursel; Kaljurand, Mihkel; Vaher, Merike

    2015-10-01

    In the present study, a micellar electrokinetic chromatographic method was used to determine the retention factors of hydrophilic monomeric and homodimeric forms of glutathione analogues. Ionic-liquid-based surfactant, 1-tetradecyl-3-methylimidazolium chloride, as well as cetyltrimethylammonium bromide and phosphate buffer (pH 7.4) were employed in the experiments. Since the studied peptides possess a negative charge under physiological conditions, it is expected that the peptides interact with the oppositely charged 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide micelles via hydrophobically assisted electrostatic forces. The dependence of the retention factor on the micellar concentration of 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide is nonlinear and the obtained curves converge to a limiting value. The retention factor values of GSH analogues were in the range of 0.36-2.22 for glutathione analogues and -1.21 to 0.37 for glutathione when 1-tetradecyl-3-methylimidazolium chloride was used. When cetyltrimethylammonium bromide was employed, the retention factor values were in the range of 0.27-2.17 for glutathione analogues and -1.22 to 0.06 for glutathione. If sodium dodecyl sulfate was used, the retention factor values of glutathione analogues with carnosine moiety were in the range of -1.54 to 0.38.

  19. Molecular mechanisms underlying a cellular analogue of operant reward learning

    PubMed Central

    Lorenzetti, Fred D.; Baxter, Douglas A.; Byrne, John H.

    2008-01-01

    SUMMARY Operant conditioning is a ubiquitous but mechanistically poorly understood form of associative learning in which an animal learns the consequences of its behavior. Using a single-cell analogue of operant conditioning in neuron B51 of Aplysia, we examined second-messenger pathways engaged by activity and reward and how they may provide a biochemical association underlying operant learning. Conditioning was blocked by Rp-cAMP, a peptide inhibitor of PKA, a PKC inhibitor and by expressing a dominant negative isoform of Ca2+-dependent PKC (apl-I). Thus, both PKA and PKC were necessary for operant conditioning. Injection of cAMP into B51 mimicked the effects of operant conditioning. Activation of PKC also mimicked conditioning, but was dependent on both cAMP and PKA, suggesting that PKC acted at some point upstream of PKA activation. Our results demonstrate how these molecules can interact to mediate operant conditioning in an individual neuron important for the expression of the conditioned behavior. PMID:18786364

  20. Why Are We Failing to Implement Imaging Studies with Radiolabelled New Molecular Entities in Early Oncology Drug Development?

    PubMed Central

    2014-01-01

    In early drug development advanced imaging techniques can help with progressing new molecular entities (NME) to subsequent phases of drug development and thus reduce attrition. However, several organizational, operational, and regulatory hurdles pose a significant barrier, potentially limiting the impact these techniques can have on modern drug development. Positron emission tomography (PET) of radiolabelled NME is arguably the best example of a complex technique with a potential to deliver unique decision-making data in small cohorts of subjects. However, to realise this potential the impediments to timely inclusion of PET into the drug development process must be overcome. In the present paper, we discuss the value of PET imaging with radiolabelled NME during early anticancer drug development, as exemplified with one such NME. We outline the multiple hurdles and propose options on how to streamline the organizational steps for future studies. PMID:25202719

  1. Radiolabeling of equine platelets in plasma with /sup 111/In-(2-mercaptopyridine-N-oxide) and their in vivo survival

    SciTech Connect

    Coyne, C.P.; Kelly, A.B.; Hornof, W.J.; O'Brien, T.R.; Philp, M.S.; Lamb, J.F.

    1987-03-01

    A method is presented for the in vitro isolation and radiolabeling of equine platelets with the isotope indium /sup 111/ (/sup 111/In: half-life = 2.8 days, gamma = 173 keV, 89%; 247 keV, 94%). The technique described involves complexing /sup 111/In with the lipid-soluble chelating agent, 2-mercaptopyridine-N-oxide (merc), in an aqueous medium. /sup 111/In-merc platelet-labeling efficiencies in autologous plasma pretreated with or without ferric citrate reagent were 82 +/- 7% and 24 +/- 12%, respectively. Mean intravascular survivals of /sup 111/In-merc-radiolabeled platelets in 8 healthy horses according to simple linear, exponential, mean, weighted-mean residual sum of squares analysis, and multiple-hit model were 5.5 +/- 0.49, 3.5 +/- 0.53, 4.5 +/- 0.18, 4.3 +/- 0.65, and 3.6 +/- 0.97 days, respectively.

  2. Synthesis and biological properties of amino acids and peptides containing a tetrazolyl moiety

    NASA Astrophysics Data System (ADS)

    Popova, E. A.; Trifonov, R. E.

    2015-09-01

    Literature data published mainly in the last 15 years on the synthesis and biological properties of amino acid analogues and derivatives containing tetrazolyl moieties are analyzed. Tetrazolyl analogues and derivatives of amino acids and peptides are shown to be promising for medicinal chemistry. Being polynitrogen heterocyclic systems comprising four endocyclic nitrogen atoms, tetrazoles can behave as acids and bases and form strong hydrogen bonds with proton donors (more rarely, with acceptors). They have high metabolic stability and are able to penetrate biological membranes. The review also considers the synthesis and properties of linear and cyclic peptides based on modified amino acids incorporating a tetrazolyl moiety. A special issue is the discussion of the biological properties of tetrazole-containing amino acids and peptides, which exhibit high biological activity and can be used to design new drugs. The bibliography includes 200 references.

  3. Plant peptide hormone signalling.

    PubMed

    Motomitsu, Ayane; Sawa, Shinichiro; Ishida, Takashi

    2015-01-01

    The ligand-receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone-receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions.

  4. Peptide transport through the blood-brain barrier. Final report 1 Jul 87-31 Dec 90

    SciTech Connect

    Partridge, W.M.

    1991-01-15

    Most neuropeptides are incapable of entering the brain from blood owing to the presence of unique anatomical structures in the brain capillary wall, which makes up the blood-brain barrier (BBB). Such neuropeptides could be introduced into the bloodstream by intranasal insufflation and, thus, could have powerful medicinal properties (e.g., Beta-endorphin for the treatment of pain, vasopressin analogues for treatment of memory, ACTH analogues for treatment of post-traumatic epilepsy), should these peptides be capable of traversing the BBB. One such strategy for peptide delivery through the BBB is the development of chimeric peptides, which is the basis of the present contract. The production of chimeric peptides involves the covalent coupling of a nontransportable peptide (e.g., Beta-endorphin, vasopressin) to a transportable vector peptide (e.g., insulin, transferrin, cationized albumin, histone). The transportable peptide is capable of penetrating the BBB via receptor-mediated or absorptive-mediated transcytosis. Therefore, the introduction of chimeric peptides allows the nontransportable peptide to traverse the BBB via a physiologic piggy back mechanism.

  5. Heat-induced-radiolabeling and click chemistry: A powerful combination for generating multifunctional nanomaterials

    PubMed Central

    Wilks, Moses Q.; El Fakhri, Georges; Normandin, Marc D.; Kaittanis, Charalambos; Josephson, Lee

    2017-01-01

    A key advantage of nanomaterials for biomedical applications is their ability to feature multiple small reporter groups (multimodality), or combinations of reporter groups and therapeutic agents (multifunctionality), while being targeted to cell surface receptors. Here a facile combination of techniques for the syntheses of multimodal, targeted nanoparticles (NPs) is presented, whereby heat-induced-radiolabeling (HIR) labels NPs with radiometals and so-called click chemistry is used to attach bioactive groups to the NP surface. Click-reactive alkyne or azide groups were first attached to the nonradioactive clinical Feraheme (FH) NPs. Resulting “Alkyne-FH” and “Azide-FH” intermediates, like the parent NP, tolerated 89Zr labeling by the HIR method previously described. Subsequently, biomolecules were quickly conjugated to the radioactive NPs by either copper-catalyzed or copper-free click reactions with high efficiency. Synthesis of the Alkyne-FH or Azide-FH intermediates, followed by HIR and then by click reactions for biomolecule attachment, provides a simple and potentially general path for the synthesis of multimodal, multifunctional, and targeted NPs for biomedical applications. PMID:28225818

  6. A simple method for enzymatic synthesis of unlabeled and radiolabeled Hydroxycinnamate-CoA

    SciTech Connect

    Rautergarten, Carsten; Baidoo, Edward; Keasling, Jay; Vibe Scheller, Henrik

    2011-07-20

    Hydroxycinnamate coenzyme A (CoA) thioesters are substrates for biosynthesis of lignin and hydroxycinna- mate esters of polysaccharides and other polymers. Hence, a supply of these substrates is essential for investigation of cell wall biosynthesis. In this study, three recombinant enzymes, caffeic acid 3-O-methyltransferase, 4-coumarate- CoA ligase 1, and 4-coumarate-CoA ligase 5, were cloned from wheat, tobacco, and Arabidopsis, respectively, and were used to synthesize {sup 14}C-feruloyl-CoA, caffeoyl-CoA, p-coumaroyl-CoA, feruloyl-CoA, and sinapoyl-CoA. The corresponding hydroxycinnamoyl-CoA thioesters were high-performance liquid chromatography purified, the only extraction/purification step necessary, with total yields between 88-95%. Radiolabeled {sup 14}C-feruloyl-CoA was generated from caffeic acid and S-adenosyl-{sup 14}C-methionine under the combined action of caffeic acid 3-O-methyltransferase and 4-coumarate-CoA ligase 1. About 70% of {sup 14}C-methyl groups from S-adenosyl methionine were incorporated into the final product. The methods presented are simple, fast, and efficient for the preparation of the hydroxycinnamate thioesters.

  7. Radiolabeled androgens and progestins as imaging agents for tumors of the prostate and breast

    SciTech Connect

    Katzenellenbogen, J.A.

    1992-08-08

    We are preparing progestins and androgens, labeled with the single photon emitters technetium-99m and rhenium-186 and the positron-emitting radionuclide fluorine-18. In both cases, ligands selected have very high affinity for the respective receptor, low affinity for blood and non-specific binders and to be reasonably resistant to metabolism: The progestins will be derivatives of the potent progestins ORG2058, norgestrel, RU486, and an unusual retroprogestin and the androgens will be derivatives of the high affinity analogs of natural and synthetic androgens. Radiometal labeling will involve carefully designed steroid conjugates with N[sub 2]S[sub 2] or related chelates, or novel metal linkages, and metal complexes that themselves mimic a steroid. Fluorine substitution will be made at positions where bulk and polarity are tolerated and metabolic defluorination is minimal. In vitro competitive binding studies will be performed on the unlabeled analogs to determine their binding characteristics towards a series of steroid receptors and blood binding proteins, and Log P values will be estimated from BPLC. Tissue distribution studies with the radiolabeled progestins will be done in estrogen-primed rats using the uterus as a target, and with the radioandrogens in estrogen-treated rats using the prostate as a target. Ultimately, in collaborative studies, these radiopharmaceuticals are to be used with SPECT or PET to image the receptor-positive tumors.

  8. Cardiac output by Doppler echocardiography in the premature baboon: Comparison with radiolabeled microspheres

    SciTech Connect

    Kinsella, J.P.; Morrow, W.R.; Gerstmann, D.R.; Taylor, A.F.; deLemos, R.A. )

    1991-04-01

    Pulsed-Doppler echocardiography (PDE) is a useful noninvasive method for determining left ventricular output (LVO). However, despite increasingly widespread use in neonatal intensive care units, validation studies in prematures with cardiopulmonary disease are lacking. The purpose of this study was to compare radiolabeled microsphere (RLM) and PDE measurements of LVO, using the critically ill premature baboon as a model of the human neonate. Twenty-two paired RLM and PDE measurements of LVO were obtained in 14 animals between 3 and 24 h of age. Average PDE LVO was 152 ml/min/kg (range, 40-258 ml/min/kg) compared to 158 ml/min/kg (range, 67-278 ml/min/kg) measured by RLM. Linear regression analysis of the paired measurements showed good correlation with a slope near unity (gamma = 0.94x + 4.20, r = 0.91, SEE = 25.7 ml). The authors conclude that PDE determinations of LVO compare well with those measured by RLM in the premature baboon. PDE appears to provide a valid estimate of LVO and should be useful in human prematures with cardiopulmonary distress.

  9. Cardiac output by Doppler echocardiography in the premature baboon: comparison with radiolabeled microspheres.

    PubMed

    Kinsella, J P; Morrow, W R; Gerstmann, D R; Taylor, A F; deLemos, R A

    1991-04-01

    Pulsed-Doppler echocardiography (PDE) is a useful noninvasive method for determining left ventricular output (LVO). However, despite increasingly widespread use in neonatal intensive care units, validation studies in prematures with cardiopulmonary disease are lacking. The purpose of this study was to compare radiolabeled microsphere (RLM) and PDE measurements of LVO, using the critically ill premature baboon as a model of the human neonate. Twenty-two paired RLM and PDE measurements of LVO were obtained in 14 animals between 3 and 24 h of age. Average PDE LVO was 152 ml/min/kg (range, 40-258 ml/min/kg) compared to 158 ml/min/kg (range, 67-278 ml/min/kg) measured by RLM. Linear regression analysis of the paired measurements showed good correlation with a slope near unity (gamma = 0.94x + 4.20, r = 0.91, SEE = 25.7 ml). We conclude that PDE determinations of LVO compare well with those measured by RLM in the premature baboon. PDE appears to provide a valid estimate of LVO and should be useful in human prematures with cardiopulmonary distress.

  10. Radiolabeling and autoradiographic tracing of Toxocara canis larvae in male mice

    SciTech Connect

    Wade, S.E.; Georgi, J.R.

    1987-02-01

    Artificially hatched infective larvae of Toxocara canis were labeled with /sup 75/Se in Medium 199 (Gibco) containing /sup 75/Se-methionine. Male CD-1 mice were infected with radiolabeled larvae by intragastric intubation or by intraperitoneal injection. At intervals of 3-56 days mice were killed and the organs prepared for compressed organ autoradiography. Radioactivity of parasitic larvae showed an exponential decrease with time, reflecting catabolism of label with a biological half life of 26 days (effective half life of 21 days) making possible experiments lasting several months. Total body larva counts, estimated by total body autoradiography, displayed an overall downward trend, but the rate of reduction was probably not constant because no significant positive or negative trends were noted from day 14 onward in the numbers of larvae. The carcass accumulated the greatest number of larvae followed by the central nervous system, liver, and lung in that order. When the numbers of larvae were considered in relationship to the mass of tissue, there were 4 groupings: central nervous system, liver, lung, carcass, and kidney, and genito-urinary organ, pelt, and intestine. No significant difference between intragastric and intraperitoneal administration was observed in the larval distribution after the larvae had left the initial site of deposition.

  11. SPECT assay of radiolabeled monoclonal antibodies. Progress report, September 1, 1992--August 24, 1993

    SciTech Connect

    Jaszczak, R.J.

    1993-08-20

    The overall goal of this project is to improve the effectiveness of single photon emission computed tomography (SPECT) to image and quantify radiolabeled monoclonal antibodies. During the past year, we have made significant progress toward this goal, and this report summarizes that work. Our efforts have been mainly directed along three fronts. First, we have developed and tested new reconstruction methods including three-dimensional iterative algorithms that model non-uniform attenuation and distance-dependent detector response. Both fan beam and parallel beam collimator geometries have been modeled and novel ways of improving the efficiency of the computationally intensive methods have been introduced. Second, an ultra-high resolution, small field-of-view pinhole collimator has been constructed and evaluated. Reconstructed spatial resolution of 1 to 3 mm (FWHM) has been achieved in phantom scans with a useful field-of-view of 9 to 10 cm. Finally, we have investigated the ability of SPECT to image and quantify astatine-211 distributions. Reconstructed images of phantom data demonstrated quantitative accuracy to within 10% with proper attenuation and scatter compensation.

  12. Endotoxin reduces specific pulmonary uptake of radiolabeled monoclonal antibody to angiotensin-converting enzyme

    SciTech Connect

    Muzykantov, V.R.; Puchnina, E.A.; Atochina, E.N.; Hiemish, H.; Slinkin, M.A.; Meertsuk, F.E.; Danilov, S.M. )

    1991-03-01

    The biodistribution of radiolabeled monoclonal antibody (Mab) to angiotensin-converting enzyme (ACE) was examined in normal and endotoxin-treated rats. Endotoxin administration at a dose of 4 mg/kg induced mild or middle pulmonary edema. The ACE activity in lung homogenate remained virtually unchanged, while the activity of serum ACE increased 15 hr after endotoxin infusion. In normal rats, anti-ACE Mab accumulates specifically in the lung after i.v. injection. Endotoxin injection induces reduction of specific pulmonary uptake of this antibody. Even in non-edematous endotoxemia, the accumulation of anti-ACE Mab antibody (Mab 9B9) decreased from 19.02 to 11.91% of ID/g of tissue without any change in accumulation of control nonspecific IgG. The antibody distribution in other organs and its blood level were almost the same as in the control. In a case of endotoxemia accompanied by increased microvascular permeability, the lung accumulation of Mab 9B9 was reduced to 9.17% of ID/g of tissue, while the accumulation of nonspecific IgG increased to 1.44% versus 0.89% in the control.

  13. Clearance and binding of radiolabeled glycoproteins by cells of the murine mononuclear phagocyte system

    SciTech Connect

    Imber, M.J.

    1982-01-01

    The clearance and binding of radiolabeled lactoferrin and fast ..cap alpha../sub 2/-macroglobulin were studied. Both glycoproteins cleared rapidly following intravenous injection in mice, and both bound specifically to discrete receptors on murine peritoneal macrophages. The simultaneous presence of excess, unlabeled ligands specific for receptors recognizing terminal fucose, mannose, N-acetylglucosamine or galactose residues did not inhibit the clearance or binding of either lactoferrin or fast-..cap alpha../sub 2/M. The clearance and binding of enzymatically defucosylated lactoferrin was indistinguishable from native lactoferrin, indicating that terminal ..cap alpha..(1-3)-linked fucose on lactoferrin is not necessary for receptor recognition. The clearance and binding of two fast -..cap alpha../sub 2/M forms, ..cap alpha../sub 2/M-trypsin and ..cap alpha../sub 2/M-MeNH/sub 2/ cross compete with each other. Saturation binding studies indicated that the total binding of mannosyl -BSA, fusocyl-BSA, and N-acetylglucosaminyl-BSA to macrophages activated by BCG was approximately 15% of the levels observed with inflammatory macrophages elicited by thioglycollate broth. Cross-competition binding studies demonstrated a common surface receptor mediated binding of all three neoglycoprotein ligands and was identical to the receptor on mononuclear phagocytes that binds mannosyl- and N-acetylglucosaminyl-terminated glycoproteins. These results suggest that difference between discrete states of macrophage function may be correlated with selective changes in levels of the surface receptor for mannose-containing glycoproteins.

  14. Bifunctional Coupling Agents for Radiolabeling of Biomolecules and Target-Specific Delivery of Metallic Radionuclides

    PubMed Central

    Liu, Shuang

    2008-01-01

    Receptor-based radiopharmaceuticals are of great current interest in early molecular imaging and radiotherapy of cancers, and provide a unique tool for target-specific delivery of radionuclides to the diseased tissues. In general, a target-specific radiopharmaceutical can be divided into four parts: targeting biomolecule (BM), pharmacokinetic modifying (PKM) linker, bifunctional coupling or chelating agent (BFC), and radionuclide. The targeting biomolecule serves as a “carrier” for specific delivery of the radionuclide. PKM linkers are used to modify radiotracer excretion kinetics. BFC is needed for radiolabeling of biomolecules with a metallic radionuclide. Different radiometals have significant difference in their coordination chemistry, and require BFCs with different donor atoms and chelator frameworks. Since the radiometal chelate can have a significant impact on physical and biological properties of the target-specific radiopharmaceutical, its excretion kinetics can be altered by modifying the coordination environment with various chelators or coligand, if needed. This review will focus on the design of BFCs and their coordination chemistry with technetium, copper, gallium, indium, yttrium and lanthanide radiometals. PMID:18538888

  15. Amyloid Plaque-Associated Oxidative Degradation of Uniformly Radiolabeled Arachidonic Acid.

    PubMed

    Furman, Ran; Murray, Ian V J; Schall, Hayley E; Liu, Qiwei; Ghiwot, Yonatan; Axelsen, Paul H

    2016-03-16

    Oxidative stress is a frequently observed feature of Alzheimer's disease, but its pathological significance is not understood. To explore the relationship between oxidative stress and amyloid plaques, uniformly radiolabeled arachidonate was introduced into transgenic mouse models of Alzheimer's disease via intracerebroventricular injection. Uniform labeling with carbon-14 is used here for the first time, and made possible meaningful quantification of arachidonate oxidative degradation products. The injected arachidonate entered a fatty acid pool that was subject to oxidative degradation in both transgenic and wild-type animals. However, the extent of its degradation was markedly greater in the hippocampus of transgenic animals where amyloid plaques were abundant. In human Alzheimer's brain, plaque-associated proteins were post-translationally modified by hydroxynonenal, a well-known oxidative degradation product of arachidonate. These results suggest that several recurring themes in Alzheimer's pathogenesis, amyloid β proteins, transition metal ions, oxidative stress, and apolipoprotein isoforms, may be involved in a common mechanism that has the potential to explain both neuronal loss and fibril formation in this disease.

  16. Optimization of hepatocarcinoma uptake with radiolabeled lipiodol: development of new lipiodol formulations with increased viscosity.

    PubMed

    Becker, Stéphanie; Lepareur, Nicolas; Cadeillan, Virginie; Ardisson, Valérie; Bayat, Sahar; Noiret, Nicolas; Garin, Etienne

    2012-03-01

    The aim of this study was to develop new Lipiodol formulations with increased viscosities to augment Lipiodol embolic effect and optimize efficiency of radiolabeled Lipiodol in hepatocarcinoma treatments. New Lipiodol formulations consist of Lipiodol mixtures with different stearic acid concentrations (0.8%, 1.3%, and 1.8%). These formulations were fully characterized in vitro (viscosity, rheologic profiles) and labeled with 99mTc. Their viscosities at 20°C are 54, 60, and 67cP respectively, versus 45cP for Lipiodol ultra-fluide. Second, their biodistribution profiles were studied in vivo, at 24 and 72 hours, in hepatoma-bearing rats, and compared to control group (99mTc-Lipiodol). Biodistribution at 24 hours show a Gaussian tumor uptake profile with a maximum obtained with 1.3% stearic acid, and a tumor uptake superior to control group (+67%) (p<0.05). At 72 hours, optimal tumor uptake is reached with the 0.8% formulation, with 89% increase compared with control group (p<0.05). Moreover, we show a tendency to the decrease of pulmonary uptake for the new formulations at 24 hours and 72 hours. These results suggest a correlation between viscosity and Lipiodol tumor uptake. The new 0.8% stearic acid/Lipiodol formulation appears to be the optimized formulation for Lipiodol treatments of hepatocarcinoma, since it leads to a significant increase of tumor uptake at 72 hours and possibly to a decrease of undesirable pulmonary effects.

  17. Free thyroxin by radioimmunoassay: evaluation of a new direct method involving a radiolabeled thyroxin analog

    SciTech Connect

    Kubasik, N.P.; Lundberg, P.A.; Brodows, R.G.; Hallauer, G.D.; Same, D.G.; Lindstedt, G.; Bengtsson, C.; Nystroem, E.

    1983-10-01

    The first performance evaluation of a new direct method for free thyroxin (T4) in serum by radioimmunoassay, with use of coated tubes and a radioiodinated T4 analog (Diagnostic Products Corp.) is presented. The assay is precise and robust: within-run imprecision (CV), 3.1-6.6%; between-run imprecision, 4.0-7.9%; no demonstrable variation between technologists irrespective of experience with the method. No outliers were observed when we compared the free T4 results with serum total T4. Reference values are reported for a total of 1243 euthyroid subjects; there was no significant age effect on serum free T4 in women 26 to 72 years old. The biological variation was about +/- 35% of the mean (2 SD). Free T4 results are the same for serum and plasma. The assay performs well in hypothyroidism and hyperthyroidism, and distinguishes individuals with thyroid disease from normal individuals. Free T4 values in women taking oral contraceptives are normal. Depressed results were often observed in acute nonthyroidal illness and continuing pregnancy. These results were directly comparable with those of another commercial direct radiolabeled-T4 analog kit for free T4.

  18. Incorporation of radiolabeled whey proteins into casein micelles by heat processing

    SciTech Connect

    Noh, B.; Richardson, T. )

    1989-07-01

    Skim milk was heated at .70, 95, and 140{degree}C to simulate the processes of pasteurization, forewarming, and UHT sterilization, and the specific interactions between {alpha}-lactalbumin or {beta}-lactoglobulin and the caseins studied using tracer amounts of added {sup 14}C-labeled whey protein. Radioactivities of the whey and of the washed casein pellets from renneted skim milk were measured and the extent of the interaction estimated. Upon heating skim milk at 70{degree}C for 45 s, less than 2% {beta}-lactoglobulin and less than .3% {alpha}-lactalbumin were incorporated into the curd. Heating at 95{degree}C for .5 to 20 min resulted in 58 to 85% of the {beta}-lactoglobulin and 8 to 55% of the {alpha}-lactalbumin becoming associated with the curd. Heating at 140{degree}C for 2 and 4 s caused 43 and 54% of the {beta}-lactoglobulin and 9 and 12% of the {alpha}-lactalbumin, respectively, to be bound to the curd fraction. The radiolabeling technique is very sensitive and useful for tracing low levels of interaction between whey proteins and casein in heated milk systems.

  19. Formation and Dissociation of Phosphorylated Peptide Radical Cations

    NASA Astrophysics Data System (ADS)

    Kong, Ricky P. W.; Quan, Quan; Hao, Qiang; Lai, Cheuk-Kuen; Siu, Chi-Kit; Chu, Ivan K.

    2012-12-01

    In this study, we generated phosphoserine- and phosphothreonine-containing peptide radical cations through low-energy collision-induced dissociation (CID) of the ternary metal-ligand phosphorylated peptide complexes [CuII(terpy) p M]·2+ and [CoIII(salen) p M]·+ [ p M: phosphorylated angiotensin III derivative; terpy: 2,2':6',2''-terpyridine; salen: N, N '-ethylenebis(salicylideneiminato)]. Subsequent CID of the phosphorylated peptide radical cations ( p M·+) revealed fascinating gas-phase radical chemistry, yielding (1) charge-directed b- and y-type product ions, (2) radical-driven product ions through cleavages of peptide backbones and side chains, and (3) different degrees of formation of [M - H3PO4]·+ species through phosphate ester bond cleavage. The CID spectra of the p M·+ species and their non-phosphorylated analogues featured fragment ions of similar sequence, suggesting that the phosphoryl group did not play a significant role in the fragmentation of the peptide backbone or side chain. The extent of neutral H3PO4 loss was influenced by the peptide sequence and the initial sites of the charge and radical. A preliminary density functional theory study, at the B3LYP 6-311++G(d,p) level of theory, of the neutral loss of H3PO4 from a prototypical model— N-acetylphosphorylserine methylamide—revealed several factors governing the elimination of neutral phosphoryl groups through charge- and radical-induced mechanisms.

  20. A preparative suspension culture system permitting quantitation of anchorage-independent growth by direct radiolabeling of cellular DNA.

    PubMed

    Assoian, R K; Boardman, L A; Drosinos, S

    1989-02-15

    We have developed a hybrid methylcellulose/agar suspension culture system which permits long-term colony formation of transformed mesenchymal cells. In contrast to traditional agar suspensions, our system allows for recovery of cells and direct biochemical analysis of anchorage-independent growth. The ability to readily radiolabel cellular macromolecules in these preparative cultures permits a quantitative and objective analysis of colony formation by incorporation of [3H]thymidine into newly synthesized DNA.

  1. Scintigraphic detection of TNF-driven inflammation by radiolabelled certolizumab pegol in patients with rheumatoid arthritis and spondyloarthritis

    PubMed Central

    Carron, Philippe; Lambert, Bieke; Van Praet, Liesbet; De Vos, Filip; Varkas, Gaëlle; Jans, Lennart; Elewaut, Dirk; Van den Bosch, Filip

    2016-01-01

    Background Biologicals are the cornerstone for many treatment algorithms in inflammatory arthritis. While tumour necrosis factor (TNF) inhibitors may achieve important responses in ∼50% of patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA), a significant fraction of patients are partial or non-responders. We hypothesised that in vivo assessment of TNF by scintigraphy with 99mTc-radiolabelled certolizumab pegol (CZP) might lead to a more ‘evidence-based biological therapy’. Objectives Our goal was to perform a proof-of-concept study of in vivo detection of TNF by immunoscintigraphy of a radiolabelled TNF inhibitor in RA and SpA, and correlate this with clinical, imaging findings and therapeutic outcome. Methods CZP was conjugated with succinimidyl-6-hydrazino-nicotinamide and subsequently radiolabelled with Tc99m. Whole body and static images of hands, feet and sacroiliac joints of 20 patients (5 RA; 15 SpA) were acquired at 3 time points. Immunoscintigraphic findings were scored semiquantitatively. Subsequently, all patients were treated with CZP. Results In peripheral joints, clinically affected joints or abnormal ultrasound findings were observed more frequently (p<0.001) in the scintigraphic-positive group. In patients with axial SpA, bone marrow edema on MRI was detected more frequently (p<0.001) in quadrants with tracer uptake. At the patient level, the odds of a joint remaining tender despite 24 weeks of CZP treatment was significantly smaller in joints with clear tracer uptake as compared with those with no uptake (OR=0.42, p=0.04). Conclusions Immunoscintigraphy with radiolabelled CZP demonstrated both axial and peripheral inflammation, and displayed good correlation with clinical features, conventional imaging and therapy response. Trial registration number NCT01590966; Results. PMID:27403334

  2. Tryptophan analogues. 1. Synthesis and antihypertensive activity of positional isomers.

    PubMed

    Safdy, M E; Kurchacova, E; Schut, R N; Vidrio, H; Hong, E

    1982-06-01

    A series of tryptophan analogues having the carboxyl function at the beta-position was synthesized and tested for antihypertensive activity. The 5-methoxy analogue 46 exhibited antihypertensive activity in the rat via the oral route and was much more potent than the normal tryptophan analogue. The methyl ester was found to be a critical structural feature for activity.

  3. Radiolabeled amino acids for tumor imaging with PET: radiosynthesis and biological evaluation of 2-amino-3-[18F]fluoro-2-methylpropanoic acid and 3-[18F]fluoro-2-methyl-2-(methylamino)propanoic acid.

    PubMed

    McConathy, Jonathan; Martarello, Laurent; Malveaux, Eugene J; Camp, Vernon M; Simpson, Nicholas E; Simpson, Chiab P; Bowers, Geoffrey D; Olson, Jeffrey J; Goodman, Mark M

    2002-05-23

    Novel radiopharmaceuticals, including amino acids, that target neoplasms through their altered metabolic states have shown promising results in preclinical and clinical studies. Two fluorinated analogues of alpha-aminoisobutyric acid, 2-amino-3-fluoro-2-methylpropanoic acid (FAMP) and 3-fluoro-2-methyl-2-(methylamino)propanoic acid (N-MeFAMP), have been radiolabeled with fluorine-18, characterized in amino acid uptake assays, and evaluated in vivo in normal rats and a rodent tumor model. The key steps in the syntheses of both radiotracers involved the preparation of cyclic sulfamidate precursors. Radiosyntheses of both [18F]FAMP and [18F]N-MeFAMP via no-carrier-added nucleophilic substitution provided high yields (>78% decay-corrected) in high radiochemical purity (>99%). Amino acid transport assays using 9L gliosarcoma cells demonstrated that both compounds are substrates for the A type amino acid transport system, with [18F]N-MeFAMP showing higher specificity than [18F]FAMP for A type transport. Tissue distribution studies in normal Fischer rats and Fischer rats implanted intracranially with 9L gliosarcoma tumor cells were also performed. At 60 min postinjection, the tumor vs normal brain ratio of radioactivity was 36:1 in animals receiving [18F]FAMP and 104:1 in animals receiving [18F]N-MeFAMP. On the basis of these studies, both [18F]FAMP and [18F]N-MeFAMP are promising imaging agents for the detection of intracranial neoplasms via positron emission tomography.

  4. Enthalpy-driven interactions with sulfated glycosaminoglycans promote cell membrane penetration of arginine peptides.

    PubMed

    Takechi-Haraya, Yuki; Nadai, Ryo; Kimura, Hitoshi; Nishitsuji, Kazuchika; Uchimura, Kenji; Sakai-Kato, Kumiko; Kawakami, Kohsaku; Shigenaga, Akira; Kawakami, Toru; Otaka, Akira; Hojo, Hironobu; Sakashita, Naomi; Saito, Hiroyuki

    2016-06-01

    The first step of cell membrane penetration of arginine peptides is thought to occur via electrostatic interactions between positive charges of arginine residues and negative charges of sulfated glycosaminoglycans (GAGs) on the cell surface. However, the molecular interaction of arginine peptides with GAG still remains unclear. Here, we compared the interactions of several arginine peptides of Tat, R8, and Rev and their analogues with heparin in relation to the cell membrane penetration efficiency. The high-affinity binding of arginine peptides to heparin was shown to be driven by large favorable enthalpy contributions, possibly reflecting multidentate hydrogen bondings of arginine residues with sulfate groups of heparin. Interestingly, the lysine peptides in which all arginine residues are substituted with lysine residues exhibited negligible binding enthalpy despite of their considerable binding to heparin. In CHO-K1 cells, arginine peptides exhibited a great cell-penetrating ability whereas their corresponding lysine peptides did not penetrate into cells. The degree of cell penetration of arginine peptides markedly decreased by the chlorate treatment of cells which prevents the sulfation of GAG chains. Significantly, the cell penetration efficiency of arginine peptides was found to be correlated with the favorable enthalpy of binding to heparin. These results suggest that the enthalpy-driven strong interaction with sulfated GAGs such as heparan sulfate plays a critical role in the efficient cell membrane penetration of arginine peptides.

  5. Direct intralymphatic injection of radiolabeled sup 111 In-T101 in patients with cutaneous T-cell lymphoma

    SciTech Connect

    Mulshine, J.L.; Carrasquillo, J.A.; Weinstein, J.N.; Keenan, A.M.; Reynolds, J.C.; Herdt, J.; Bunn, P.A.; Sausville, E.; Eddy, J.; Cotelingam, J.D. )

    1991-01-15

    Direct intralymphatic administration of radiolabeled monoclonal antibody in targeting antigen-bearing lymphoma cells in regional lymph nodes of patients with cutaneous T-cell lymphoma was evaluated. Seven consecutive patients undergoing staging lymphangiography received intralymphatic infusions of {sup 111}In-T101 to evaluate lymph node involvement. This procedure was accomplished without significant complication. The {sup 111}In-T101 rapidly distributed throughout the regional lymphatic compartment and passed into the systemic circulation. Tumor-bearing sites in the inguinal-femoral lymph nodes retained from 0.42 to 4.8% of the injected dose of radiolabeled antibody. Three patients were upstaged to Stage IVA based on tumor involvement found after radiolymphoscintigraphy-directed biopsy of groin lymph nodes, selected because of intense radioactivity by gamma camera imaging. Compared with previously reported s.c. antibody administration, there was a marked reduction in the radioactive exposure of normal tissues at the injection sites in the lower extremities. Direct intralymphatic delivery of {sup 111}In-T101 appears to be a feasible, efficient method for delivering therapeutic doses of radiolabeled antibody.

  6. MBP-annexin V radiolabeled directly with iodine-124 can be used to image apoptosis in vivo using PET.

    PubMed

    Dekker, Bronwen; Keen, Heather; Lyons, Stephen; Disley, Lynn; Hastings, David; Reader, Andrew; Ottewell, Penny; Watson, Alastair; Zweit, Jamal

    2005-04-01

    A noninvasive method of measuring programmed cell death in the tumors of cancer patients using positron-emission tomography (PET) would provide valuable information regarding their response to therapeutic intervention. Our strategy is to radiolabel annexin V, a protein that binds to phosphatidylserine moieties that are translocated to the external leaflet of plasma membranes during apoptosis. We developed a phosphatidylserine-ELISA capable of distinguishing wild type from point mutant annexin V that is known to have a lower phosphatidylserine binding affinity. A maltose-binding protein/annexin V chimera was synthesized and purified with high yield using amylose resin. We showed that it bound to phosphatidylserine in the ELISA as well as to that exposed on apoptotic Jurkat cells; therefore, it was used in the development of a method for radiolabeling annexin V using iodine radionuclides. MBP-annexin V retained its phosphatidylserine binding properties on direct iodination, but at high levels of oxidizing agents (iodogen and chloramine T), its specificity for phosphatidylserine was compromised. (124)I-MBP-annexin V was successfully used to image Fas-mediated hepatic cell death in BDF-1 mice using PET. In conclusion, we have shown that MBP-annexin V and the phosphatidylserine ELISA are useful tools for the development of methods for radiolabeling annexin V for PET imaging.

  7. A Randomized Phase 2 Trial of 177Lu Radiolabeled Anti-PSMA Monoclonal Antibody J591 in Patients With High-Risk Castrate Biochemically Relapsed Prostate Cancer

    DTIC Science & Technology

    2015-09-01

    Award Number: W81XWH-09-1-0596 TITLE: A Randomized Phase 2 Trial of 177Lu Radiolabeled Anti- PSMA Monoclonal Antibody J591 in Patients With High...1-0596 A Randomized Phase 2 Trial of 177Lu Radiolabeled Anti- PSMA Monoclonal Antibody J591 in Patients With High-Risk Castrat Biochemically Relapsed...in December 2014 with approval to proceed without modifications. 15. SUBJECT TERMS Prostate cancer, PSA, PSMA , monoclonal antibody

  8. Enduracidin analogues with altered halogenation patterns produced by genetically engineered strains of Streptomyces fungicidicus.

    PubMed

    Yin, Xihou; Chen, Ying; Zhang, Ling; Wang, Yang; Zabriskie, T Mark

    2010-04-23

    Enduracidins (1, 2) and ramoplanin (3) are structurally and functionally closely related lipodepsipeptide antibiotics. They are active against multi-drug-resistant Gram-positive pathogens, including MRSA. Each peptide contains one chlorinated non-proteinogenic amino acid residue, Cl(2)-Hpg or Cl-Hpg. To investigate the timing of halogenation and the importance of chlorination on bioactivity and bioavailability of enduracidin, and to probe the substrate specificity and portability of the ramoplanin halogenase, we constructed the mutant strain SfDelta30 in which the enduracidin halogenase gene orf30 had been deleted and complemented it with the ramoplanin counterpart orf20. We also expressed orf20 in the enduracidin wild-type producer. Metabolite analysis revealed SfDelta30 produced the novel analogues dideschloroenduracidins A (4) and B (5), while the recombinant strains SfDelta30R20 and SfR20 produced monodeschloroenduracidins A (6) and B (7) and a trichlorinated enduracidin (8), respectively. In addition, orf30 self-complementation yielded the strain SfDelta30E30, which is capable of producing six peptides including 6 and 7. MS/MS analysis positioned the single chlorine atom in 6 at Hpg(13) and localized the third chlorine atom in 8 to Hpg(11). Biological evaluation of these enduracidin analogues indicated that all retained activity against Staphylococcus aureus. Our findings lay the foundation for further utilization of enduracidin and ramoplanin halogenases in combinatorial biosynthesis.

  9. Biological and structural characterization of new linear gomesin analogues with improved therapeutic indices.

    PubMed

    Fázio, Marcos A; Jouvensal, Laurence; Vovelle, Françoise; Bulet, Philippe; Miranda, M Terêsa M; Daffre, Sirlei; Miranda, Antonio

    2007-01-01

    Gomesin (Gm) is a potent antimicrobial peptide isolated from the spider Acanthoscurria gomesiana. The two disulfide bridges Cys(2,15) and Cys(6,11) facilitate the folding of the molecule in a beta-hairpin structure, conferring on the peptide a high stability in human plasma. We report herein biological and structural features of new linear Gm analogues, obtained by combining the removal of both disulfide bridges and the incorporation of a D- or L-proline. Regarding their biological properties, two analogues, namely, [D-Thr(2,6,11,15), Pro(9)]-D-Gm and [Thr(2,6,11,15), D-Pro(9)]-Gm, are as potent as Gm against Candida albicans and only fourfold less against Staphylococcus aureus and Escherichia coli. In addition, at 100 microM they are approximately threefold less hemolytic than Gm. The best therapeutic indices were found for [D-Thr(2,6,11,15), Pro(9)]-D-Gm and for [(Des-pGlu(1), -Thr(2), -Arg(3)), Thr(6,11,15), D-Pro(9)]-Gm with a 32-fold increase of their activity against bacteria, and from 128- to 512-fold against yeast when compared with Gm. Regarding the stability, [D-Thr(2,6,11,15), Pro(9)]-D-Gm appeared to be the most resistant in human serum, along with [D-Thr(2,6,11,15), Pro(8)]-D-Gm and [Thr(2,6,11,15), D-Arg(4,16), D-Pro(9)]-Gm. When evaluating their conformation by CD spectroscopy in sodium dodecyl sulfate (SDS), most linear analogues display beta-conformation characteristics. Moreover, considering its high therapeutic index and stability in serum, [D-Thr(2,6,11,15), Pro(9)]-D-Gm was further analyzed by NMR spectroscopy. (1)H NMR experiments in SDS micelles demonstrated that [D-Thr(2,6,11,15), Pro(9)]-D-Gm presents a conformation very similar to that of Gm. In our search for Gm analogues with enhanced potential for drug development, we demonstrated that designing cysteine-free analogues can improve the therapeutic index of Gm derivatives.

  10. Design of cell-permeable stapled peptides as HIV-1 integrase inhibitors.

    PubMed

    Long, Ya-Qiu; Huang, Shao-Xu; Zawahir, Zahrah; Xu, Zhong-Liang; Li, Huiyuan; Sanchez, Tino W; Zhi, Ying; De Houwer, Stephanie; Christ, Frauke; Debyser, Zeger; Neamati, Nouri

    2013-07-11

    HIV-1 integrase (IN) catalyzes the integration of viral DNA into the host genome, involving several interactions with the viral and cellular proteins. We have previously identified peptide IN inhibitors derived from the α-helical regions along the dimeric interface of HIV-1 IN. Herein, we show that appropriate hydrocarbon stapling of these peptides to stabilize their helical structure remarkably improves the cell permeability, thus allowing inhibition of the HIV-1 replication in cell culture. Furthermore, the stabilized peptides inhibit the interaction of IN with the cellular cofactor LEDGF/p75. Cellular uptake of the stapled peptide was confirmed in four different cell lines using a fluorescein-labeled analogue. Given their enhanced potency and cell permeability, these stapled peptides can serve as not only lead IN inhibitors but also prototypical biochemical probes or "nanoneedles" for the elucidation of HIV-1 IN dimerization and host cofactor interactions within their native cellular environment.

  11. Characterization of a new bioactive peptide from Potamotrygon gr. orbignyi freshwater stingray venom.

    PubMed

    Conceição, Katia; Santos, Juliane M; Bruni, Fernanda M; Klitzke, Clécio F; Marques, Elineide E; Borges, Márcia H; Melo, Robson L; Fernandez, Jorge H; Lopes-Ferreira, Mônica

    2009-12-01

    Brazilian freshwater stingrays, Potamotrygon gr. orbigyni, are relatively common in the middle-western regions of Brazil, where they are considered an important public health threat. In order to identify some of their naturally occurring toxin peptides available in very low amounts, we combine analytical protocols such as reversed-phase high-performance liquid chromatography (RP-HPLC), followed by a biological microcirculatory screening and mass spectrometry analysis. Using this approach, one bioactive peptide was identified and characterized, and two analogues were synthesized. The natural peptide named Porflan has the primary structure ESIVRPPPVEAKVEETPE (MW 2006.09 Da) and has no similarity with any bioactive peptide or protein found in public data banks. Bioassay protocols characterized peptides as presenting potent activity in a microcirculatory environment. The primary sequences and bioassay results, including interactions with the membrane phospholipids, suggest that these toxins are a new class of fish toxins, directly involved in the inflammatory processes of a stingray sting.

  12. Polycyclic peptide therapeutics.

    PubMed

    Baeriswyl, Vanessa; Heinis, Christian

    2013-03-01

    Owing to their excellent binding properties, high stability, and low off-target toxicity, polycyclic peptides are an attractive molecule format for the development of therapeutics. Currently, only a handful of polycyclic peptides are used in the clinic; examples include the antibiotic vancomycin, the anticancer drugs actinomycin D and romidepsin, and the analgesic agent ziconotide. All clinically used polycyclic peptide drugs are derived from natural sources, such as soil bacteria in the case of vancomycin, actinomycin D and romidepsin, or the venom of a fish-hunting coil snail in the case of ziconotide. Unfortunately, nature provides peptide macrocyclic ligands for only a small fraction of therapeutic targets. For the generation of ligands of targets of choice, researchers have inserted artificial binding sites into natural polycyclic peptide scaffolds, such as cystine knot proteins, using rational design or directed evolution approaches. More recently, large combinatorial libraries of genetically encoded bicyclic peptides have been generated de novo and screened by phage display. In this Minireview, the properties of existing polycyclic peptide drugs are discussed and related to their interesting molecular architectures. Furthermore, technologies that allow the development of unnatural polycyclic peptide ligands are discussed. Recent application of these technologies has generated promising results, suggesting that polycyclic peptide therapeutics could potentially be developed for a broad range of diseases.

  13. Antimicrobial Peptides in Reptiles

    PubMed Central

    van Hoek, Monique L.

    2014-01-01

    Reptiles are among the oldest known amniotes and are highly diverse in their morphology and ecological niches. These animals have an evolutionarily ancient innate-immune system that is of great interest to scientists trying to identify new and useful antimicrobial peptides. Significant work in the last decade in the fields of biochemistry, proteomics and genomics has begun to reveal the complexity of reptilian antimicrobial peptides. Here, the current knowledge about antimicrobial peptides in reptiles is reviewed, with specific examples in each of the four orders: Testudines (turtles and tortosises), Sphenodontia (tuataras), Squamata (snakes and lizards), and Crocodilia (crocodilans). Examples are presented of the major classes of antimicrobial peptides expressed by reptiles including defensins, cathelicidins, liver-expressed peptides (hepcidin and LEAP-2), lysozyme, crotamine, and others. Some of these peptides have been identified and tested for their antibacterial or antiviral activity; others are only predicted as possible genes from genomic sequencing. Bioinformatic analysis of the reptile genomes is presented, revealing many predicted candidate antimicrobial peptides genes across this diverse class. The study of how these ancient creatures use antimicrobial peptides within their innate immune systems may reveal new understandings of our mammalian innate immune system and may also provide new and powerful antimicrobial peptides as scaffolds for potential therapeutic development. PMID:24918867

  14. The natriuretic peptides.

    PubMed

    Baxter, Gary F

    2004-03-01

    The natriuretic peptides are a family of widely distributed, but evolutionarily conserved, polypeptide mediators that exert a range of actions throughout the body. In cardiovascular homeostasis, the endocrine roles of the cardiac-derived atrial and B-type natriuretic peptide (ANP and BNP) in regulating central fluid volume and blood pressure have been recognised for two decades. However, there is a growing realisation that natriuretic peptide actions go far beyond their volume regulating effects. These pleiotropic actions include local (autocrine/paracrine) regulatory actions of ANP and BNP within the heart, and of another natriuretic peptide, CNP, within the vessel wall. Effects on function and growth of the local tissue environment are likely to be of great importance, especially in disease states where tissue and circulating levels of ANP and BNP rise markedly. At present, the relevance of other natriuretic peptides (notably uroguanylin and DNP) to human physiology and pathology remain uncertain. Other articles in this issue of Basic Research in Cardiology review the molecular physiology of natriuretic peptide signalling, with a particular emphasis on the lessons from genetically targetted mice; the vascular activity of natriuretic peptides; the regulation and roles of natriuretic peptides in ischaemic myocardium; and the diagnostic, prognostic and therapeutic roles of natriuretic peptides in heart failure.

  15. Adrenal medulla imaging agents: a structure-distribution relationship study of radiolabeled aralkylguanidines

    SciTech Connect

    Wieland, D.M.; Mangner, T.J.; Inbasekaran, M.N.; Brown, L.E.; Wu, J.L.

    1984-02-01

    Fourteen /sup 125/I-labeled aralkylguanidines were synthesized and evaluated as potential imaging agents for the adrenal medullae and tumors of adrenomedullary origin. These guanidines are radiotracer analogues of guanethidine, an antihypertensive agent thought to mediate neuron blockade by uptake into adrenergic nerves. Dog adrenal medullae were used as a model to test radiotracer affinity for catecholamine storage tissue. Tissue distribution studies revealed that a number of radioiodinated guanidines showed pronounced localization in the adrenal medullae following intravenous injection, in certain cases exceeding that of either (-)-(/sup 3/H)norepinephrine or (/sup 14/C)guanethidine. (m-(/sup 125/I)Iodobenzyl)guanidine (m-IBG, 2b) gave the best combination of high concentration and selectivity. The low adrenomedullary affinity observed with (/sup 14/C)guanidine and m-(/sup 125/I)iodobenzylamine demonstrates the uniqueness of the aralkylguanidine structure. Preliminary evidence suggests that 2b is a storage analogue of norepinephrine. (/sup 125/I)2a is now being used clinically in imaging and radiotherapy of catecholamine tumors, such as pheochromocytoma.

  16. Design and development of receptor-avid peptide conjugates for in-vivo targeting of cancer

    NASA Astrophysics Data System (ADS)

    Volkert, Wynn A.; Hoffman, Timothy J.

    1999-07-01

    Radiometallated peptides that exhibit high specificity for cognate receptors over expressed on cancer cells offer important potential as site-directed diagnostic and therapeutic radiopharmaceutical. The formation of effective radioactive drugs for specific in vivo targeting of cancerous tumors is being facilitated by the integration of novel chelation strategies and receptor-avid derivatives. Significant efforts are being made to design Technetium-99m labeled for diagnostic imaging of cancerous tumors for use in conjunction with Single Photon Emission Tomography instrumentation in nuclear medicine. Receptor avid radiopharmaceutical are also being developed that utilize other radionuclides for imaging and therapeutic applications. Despite the technological challenges that must be overcome, radiolabeled receptor avid peptide conjugates are providing promising site-directed targeting agents for the assessment and treatment of cancerous tumors in humans.

  17. Optimization of propafenone analogues as antimalarial leads.

    PubMed

    Lowes, David J; Guiguemde, W Armand; Connelly, Michele C; Zhu, Fangyi; Sigal, Martina S; Clark, Julie A; Lemoff, Andrew S; Derisi, Joseph L; Wilson, Emily B; Guy, R Kiplin

    2011-11-10

    Propafenone, a class Ic antiarrythmic drug, inhibits growth of cultured Plasmodium falciparum. While the drug's potency is significant, further development of propafenone as an antimalarial would require divorcing the antimalarial and cardiac activities as well as improving the pharmacokinetic profile of the drug. A small array of propafenone analogues was designed and synthesized to address the cardiac ion channel and PK liabilities. Testing of this array revealed potent inhibitors of the 3D7 (drug sensitive) and K1 (drug resistant) strains of P. falciparum that possessed significantly reduced ion channel effects and improved metabolic stability. Propafenone analogues are unusual among antimalarial leads in that they are more potent against the multidrug resistant K1 strain of P. falciparum compared to the 3D7 strain.

  18. Enzymatic synthesis of lipid II and analogues.

    PubMed

    Huang, Lin-Ya; Huang, Shih-Hsien; Chang, Ya-Chih; Cheng, Wei-Chieh; Cheng, Ting-Jen R; Wong, Chi-Huey

    2014-07-28

    The emergence of antibiotic resistance has prompted active research in the development of antibiotics with new modes of action. Among all essential bacterial proteins, transglycosylase polymerizes lipid II into peptidoglycan and is one of the most favorable targets because of its vital role in peptidoglycan synthesis. Described in this study is a practical enzymatic method for the synthesis of lipid II, coupled with cofactor regeneration, to give the product in a 50-70% yield. This development depends on two key steps: the overexpression of MraY for the synthesis of lipid I and the use of undecaprenol kinase for the preparation of polyprenol phosphates. This method was further applied to the synthesis of lipid II analogues. It was found that MraY and undecaprenol kinase can accept a wide range of lipids containing various lengths and configurations. The activity of lipid II analogues for bacterial transglycolase was also evaluated.

  19. Development & automation of a novel [(18)F]F prosthetic group, 2-[(18)F]-fluoro-3-pyridinecarboxaldehyde, and its application to an amino(oxy)-functionalised Aβ peptide.

    PubMed

    Morris, Olivia; Gregory, J; Kadirvel, M; Henderson, Fiona; Blykers, A; McMahon, Adam; Taylor, Mark; Allsop, David; Allan, Stuart; Grigg, J; Boutin, Herve; Prenant, Christian

    2016-10-01

    2-[(18)F]-Fluoro-3-pyridinecarboxaldehyde ([(18)F]FPCA) is a novel, water-soluble prosthetic group. It's radiochemistry has been developed and fully-automated for application in chemoselective radiolabelling of amino(oxy)-derivatised RI-OR2-TAT peptide, (Aoa-k)-RI-OR2-TAT, using a GE TRACERlab FX-FN. RI-OR2-TAT is a brain-penetrant, retro-inverso peptide that binds to amyloid species associated with Alzheimer's Disease. Radiolabelled (Aoa-k)-RI-OR2-TAT was reproducibly synthesised and the product of the reaction with FPCA has been fully characterised. In-vivo biodistribution of [(18)F]RI-OR2-TAT has been measured in Wistar rats.

  20. Polyamine analogues targeting epigenetic gene regulation.

    PubMed

    Huang, Yi; Marton, Laurence J; Woster, Patrick M; Casero, Robert A

    2009-11-04

    Over the past three decades the metabolism and functions of the polyamines have been actively pursued as targets for antineoplastic therapy. Interactions between cationic polyamines and negatively charged nucleic acids play a pivotal role in DNA stabilization and RNA processing that may affect gene expression, translation and protein activity. Our growing understanding of the unique roles that the polyamines play in chromatin regulation, and the discovery of novel proteins homologous with specific regulatory enzymes in polyamine metabolism, have led to our interest in exploring chromatin remodelling enzymes as potential therapeutic targets for specific polyamine analogues. One of our initial efforts focused on utilizing the strong affinity that the polyamines have for chromatin to create a backbone structure, which could be combined with active-site-directed inhibitor moieties of HDACs (histone deacetylases). Specific PAHAs (polyaminohydroxamic acids) and PABAs (polyaminobenzamides) polyamine analogues have demonstrated potent inhibition of the HDACs, re-expression of p21 and significant inhibition of tumour growth. A second means of targeting the chromatin-remodelling enzymes with polyamine analogues was facilitated by the recent identification of flavin-dependent LSD1 (lysine-specific demethylase 1). The existence of this enzyme demonstrated that histone lysine methylation is a dynamic process similar to other histone post-translational modifications. LSD1 specifically catalyses demethylation of mono- and di-methyl Lys4 of histone 3, key positive chromatin marks associated with transcriptional activation. Structural and catalytic similarities between LSD1 and polyamine oxidases facilitated the identification of biguanide, bisguanidine and oligoamine polyamine analogues that are potent inhibitors of LSD1. Cellular inhibition of LSD1 by these unique compounds led to the re-activation of multiple epigenetically silenced genes important in tumorigenesis. The use of

  1. Benchmarking analogue models of brittle thrust wedges

    NASA Astrophysics Data System (ADS)

    Schreurs, Guido; Buiter, Susanne J. H.; Boutelier, Jennifer; Burberry, Caroline; Callot, Jean-Paul; Cavozzi, Cristian; Cerca, Mariano; Chen, Jian-Hong; Cristallini, Ernesto