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Malignant Large Bowel Obstruction
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Alexander Heriot, J. Alastair D. Simpson
At least one retrospective study has suggested that primary chemotherapeutic intervention in intestinal obstruction as a consequence of advanced ovarian malignancy is at least as effective as surgical management. Although the proportion of MLBO in this study was only 19% compared to 81% small bowel obstruction.71 The evidence supporting the use of somatostatin and its analogues, octreotide and vapreotide as a primary treatment for MLBO is weak, but they have been used to alleviate symptoms when the obstruction occurs in the setting of ovarian malignancy.72 Somatostatin inhibits glucagon and insulin, reduces acid secretion, decreases intestinal motility and reduces bile flow. Octreotide acts in a similar way to somatostatin but has a longer half-life. It inhibits growth hormone, glucagon, and insulin more potently. Octreotide also suppresses luteinising hormone response to gonadotropin-releasing hormone and inhibits release of gastrin, secretin, vasoactive intestinal peptide, motilin and pancreatic polypeptide.
Radionuclide imaging of carcinoid tumors, neurendocrine tumors of the pancreas and adrenals
Published in Demetrius Pertsemlidis, William B. Inabnet III, Michel Gagner, Endocrine Surgery, 2017
Technetium-labeled investigational somatostatin analogs have also been investigated with favorable results in GEPNETs, and these included 99mTc-depreotide, which binds with high affinity to SSTR2, SSTR3, and SSTR5; 99mTc-vapreotide, which binds with high affinity to SSTR2 and SSTR5 and, to a lesser extent, SSTR3 and SSTR4; 99mTc-HYNIC-TOC; and 99mTc-HYNIC-[Tyr3,Thr8]-octreotide (TATE) [29, 65, 72]. There are advantages of 99mTc-labeled somatostatin analogs over 111In-DTPA-octreotide imparted by superior imaging capabilities of the extrahepatic metastases and better individual separation of lesions. However, these results should be analyzed with caution since most of these reported comparisons did not use the optimal imaging protocols for 111In-DTPA-octreotide SRS defined by the European and U.S. guidelines [20–23].
Radiometallo-Labeled Peptides in Tumor Diagnosis and Therapy
Published in Astrid Sigel, Helmut Sigel, Metal Ions in Biological Systems, 2004
Mihaela Ginj, Helmut R. Maecke
Because of the kinetic lability of hard radiometals like Y3+, Lu3+, lanthanides in general, but also Cu2+, Co2+, etc., and the competition in human blood and other body fluids by proteins like transferrin, albumin and anions like , , etc., peptides can not offer any functional groups which provide enough kinetic stability to ensure intact arrival of the radiometal-peptide conjugate at the target. This is different for the pair Tc and Re which form kinetically inert metal complexes in several oxidation states. In addition, both metals show a high degree of thiophilicity making sulfur containing peptidic sequences attractive for the binding of these radiometals. Several groups took advantage of this thiophilicity and labeled disulfide-bridged analogs of somatostatin like octreotide, lanreo-tide and vapreotide directly with 99mTc and 188Re [12]. Unfortunately, none of these peptides is very well characterized; in addition, they are too lipophilic, mainly excreted by the hepatobiliary system and never made the step from preclinical studies to the clinic. Still, Re-vapreotide (Figure 2d) was synthesized on a macroscopic level and studied using two dimensional iH-NMR spectroscopy and molecular dynamic simulations [13]. It was found that the metal coordinated peptide maintains the spatial topography and solution conformation as the unmodified peptide consisting of an antiparallel β sheet and type II β turn around D-Trp4-Lys5. The study did not confirm the hypothesis that during synthesis the disulfide bridge is opened creating two thiolate groups for 99mTc and 188Re coordination and no receptor affinities have been reported for these peptides.
A plausible way for excretion of metal nanoparticles via active targeting
Published in Drug Development and Industrial Pharmacy, 2020
All chemicals were of analytical grades. Vapreotide (VAP) was purchased from ChemPep (Wellington, USA). N,N-diisopropylethylamine (DIPEA), albumen bovine serum (BSA), nitric acid, hydrochloric acid, triethanolamine buffer, and ethylene di-amin tetraacetic acid (EDTA) were purchased from Sigma Aldrich (Steinheim, Germany). Quantum dots (QDs) carrying PEG-amine, Dulbecco’s phosphate-buffered saline (pH 7.2), Dulbecco’s Modified Eagle Medium, and Leibovitz′s L-15, and Sulfo-SMCC (sulfosuccinimidyl 4-(N-maleimidomethyl)-cyclohexane-1-carboxylate) were purchased from Life Technologies Ltd, (Paisley PA4 9RF, UK). The ultrafiltration units with 100-kDa cutoff membrane were obtained from Amicon Ultra-4 Millipore (Billerica, MA).