Markus Beitzel - Academia.edu (original) (raw)

Papers by Markus Beitzel

Nuclear Medicine and Biology, 1998

These studies describe the production and purification of 211 At as well as the procedure for lab... more These studies describe the production and purification of 211 At as well as the procedure for labeling humanized anti-Tac, the antibody to the ␣-chain of the IL-2 receptor (IL-2R␣), which has been shown to be a useful target for immunotherapy. The optimized protocol combines the advantages of the two-stage dry distillation procedure with the astatination of trialkylstannyl substances as labeling compounds for proteins. The 211 At was produced by bombarding either an external or a recently developed disposable internal bismuth target with ␣-particles from a Cyclotron Corporation CS-30 cyclotron. The 211 At was found to contain less than 0.01% 210 At. The production rate for the external target was 0.15 mCi ؎ 0.056 A ؊1 h ؊1 (n ‫؍‬ 9) (5.55 MBq A ؊1 h ؊1). The production rate for the internal target was 0.44 ؎ 0.14 mCi A ؊1 h ؊1 (n ‫؍‬ 16) (16.28 MBq A ؊1 h ؊1).

Nuclear Medicine and Biology, Aug 1, 2003

Detailed synthesis of the bifunctional chelating agents 2-methyl-6-(p-isothiocyanatobenzyl)-1,4,7... more Detailed synthesis of the bifunctional chelating agents 2-methyl-6-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10tetraacetic acid (1B4M-DOTA) and 2-(p-isothiocyanatobenzyl)-5, 6-cyclohexano-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetate (CHX-DOTA) are reported. These chelating agents were compared to 2-(p-isothiocyanatobenzyl)-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (C-DOTA) and 1, 4, 7, 10-Tetraaza-N-(1-carboxy-3-(4-nitrophenyl)propyl)-NЈ, NЉ, Nٞ-tris(acetic acid) cyclododecane (PA-DOTA) as their 177 Lu radiolabeled conjugates with Herceptin™. In vitro stability of the immunoconjugates radiolabeled with 177 Lu was assessed by serum stability studies. The in vivo stability of the radiolabeled immunoconjugates and their targeting characteristics were determined by biodistribution studies in LS-174T xenograft tumor-bearing mice. Relative radiolabeling rates and efficiencies were determined for all four immunoconjugates. Insertion of the 1B4M moiety into the DOTA backbone increases radiometal chelation rate and provides complex stability comparable to C-DOTA and PA-DOTA while the CHX-DOTA appears to not form as stable a 177 Lu complex while exhibiting a substantial increase in formation rate. The 1B4M-DOTAmay have potential for radioimmunotherapy applications.

Nuclear Medicine and Biology, 2001

The syntheses, radiolabeling, antibody conjugation, and in vivo evaluation of new linkers for 211... more The syntheses, radiolabeling, antibody conjugation, and in vivo evaluation of new linkers for 211At labeling of humanized anti-Tac (Hu-anti-Tac), an antibody to the alpha-chain of the IL-2 receptor (IL-2Ralpha) shown to be a useful target for radioimmunotherapy are described. Synthesis of the organometallic linker precursors is accomplished by reaction of the corresponding bromo- or iodoaryl esters with bis(tributyltin) in the presence of a palladium catalyst. Subsequent conversion to the corresponding N-succinimidyl ester and labeling with 211At of two new linkers, N-succinimidyl 4-[211At]astato-3-methylbenzoate and N-succinimidyl N-(4-[211At]astatophenethyl)succinamate (SAPS), together with the previously reported N-succinimidyl 4-[211At]astatobenzoate and N-succinimidyl 3-[211At]astato-4-methylbenzoate, are each conjugated to Hu-anti-Tac. The plasma survival times of these conjugates are compared to those of directly iodinated (125I) Hu-anti-Tac. The N-succinimidyl N-(4-[211At]astatophenethyl)succinamate compound (SAPS) emerged from this assay as the most viable candidate for 211At-labeling of Hu-anti-Tac. SAPS, along with the directly analogous radio-iodinated reagent, N-succinimidyl N-(4-[125I]astatophenethyl)succinamate (SIPS), are evaluated in a biodistribution study along with directly iodinated (125I) Hu-anti-Tac. Blood clearance and biological accretion results indicate that SAPS is a viable candidate for further evaluation for radioimmunotherapy of cancer.

Nuclear Medicine and Biology, Feb 1, 1998

ChemInform, Sep 1, 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Caoutchoucs Plastiques, 2001

○ La toute derniere generation de Thermoplast K, une nouvelle famille d'elastomeres thermopla... more ○ La toute derniere generation de Thermoplast K, une nouvelle famille d'elastomeres thermoplastiques, presente une meilleure resistance a l'exposition aux conditions exterieures.

Kunststoffe, 1998

Quality-assured extruded sealing profiles in further-developed thermoplastic elastomers based on ... more Quality-assured extruded sealing profiles in further-developed thermoplastic elastomers based on SEB-S comply with the current guideline for plastic window systems issued by the RAL quality grouping.

Tetrahedron, 1992

... Stereoselective synthesis of taxol derivatives. Siegfried Blechert, * , Reinhard Müller and M... more ... Stereoselective synthesis of taxol derivatives. Siegfried Blechert, * , Reinhard Müller and Markus Beitzel. Technische Universität Berlin, Straße des 17. ... References and Notes: 1. a) GueritteVoegelein, F.; Guenard, D.; Lavelle, F.; Le Goff, M.; Mangatal, L.; Potier, PJ Med. Chem. ...

Journal of Neurosurgery, 2003

Object. Convection-enhanced delivery (CED), the delivery and distribution of drugs by the slow bu... more Object. Convection-enhanced delivery (CED), the delivery and distribution of drugs by the slow bulk movement of fluid in the extracellular space, allows delivery of therapeutic agents to large volumes of the brain at relatively uniform concentrations. This mode of drug delivery offers great potential for the treatment of many neurological disorders, including brain tumors, neurodegenerative diseases, and seizure disorders. An analysis of the treatment efficacy and toxicity of this approach requires confirmation that the infusion is distributed to the targeted region and that the drug concentrations are in the therapeutic range. Methods. To confirm accurate delivery of therapeutic agents during CED and to monitor the extent of infusion in real time, albumin-linked surrogate tracers that are visible on images obtained using noninvasive techniques (iopanoic acid [IPA] for computerized tomography [CT] and Gd—diethylenetriamine pentaacetic acid for magnetic resonance [MR] imaging) were d...

Journal of Chromatography A, 1997

A general process for the purification of large quantities (5-10 g) of p-nitrobenzyl C-functional... more A general process for the purification of large quantities (5-10 g) of p-nitrobenzyl C-functionalized diethylenetriamine pentaacetic acids is reported. The method of choice to achieve purification for clinical applications is anion-exchange chromatography.