Peter A. M. de Witte

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We have labelled hypericin, a polyphenolic polycyclic quinone found in St. John’s wort (Hypericum perforatum), with 123I and evaluated mono-[123I]iodohypericin (MIH) as a potential necrosis-avid diagnostic tracer agent. MIH was prepared by an electrophilic radioiodination method. The new tracer agent was evaluated in animal models of liver infarction in the(More)
To study whether formulation influences biodistribution, necrosis avidity and tumoricidal effects of the radioiodinated hypericin, a necrosis avid agent for a dual-targeting anticancer radiotherapy. Iodine-123- and 131-labeled hypericin (123I-Hyp and 131I-Hyp) were prepared with Iodogen as oxidant, and formulated in dimethyl sulfoxide (DMSO)/PEG400(More)
OBJECTIVES To study the effect of co-injecting unlabelled hypericin (Hyp) on biodistribution, necrosis uptake and tumour retention of iodine-123 or iodine-131 labelled hypericin ((123/131)I-Hyp), a necrosis avid agent for an anticancer radiotherapy. METHODS (123/131)I-Hyp was prepared with Iodogen as oxidant and formulated in 0.6 μg/kg no-carrier-added(More)
We sought to establish and characterize a mouse liver tumor model as a platform for preclinical assessment of new diagnostics and therapeutics. Radiation-induced fibrosarcoma (RIF-1) was intrahepatically implanted in 27 C3H/Km mice. Serial in vivo magnetic resonance imaging (MRI) with a clinical 1.5-T-magnet was performed using T1- (T1WI), T2- (T2WI), and(More)
Cancer is one of the major causes of death for non-transmissible chronic diseases worldwide. Conventional treatments including surgery, chemotherapy and external beam radiotherapy are generally far from curative. Complementary therapies are attempted for achieving more successful treatment response. Systemic targeted radiotherapy (STR) is a radiotherapeutic(More)
We investigated the influence of two types of vascular damaging agents (VDAs) (DMXAA vs. ZD6126) and sequence of administration (VDA 24 h before HYP vs. HYP 1 h before VDA) to evaluate the effect on hypericin (HYP) accumulation and distribution in necrotic tumors. Frozen sections of dorsally inoculated RIF-1 tumors were analyzed by fluorescence microscopy(More)
RATIONALE Latent infection with Mycobacterium tuberculosis is defined by a positive IFN-γ release assay (IGRA) result in the absence of active tuberculosis. Only few, mostly monocentric studies have evaluated the role of IGRAs to predict the development of tuberculosis in recent contacts in low-incidence countries of tuberculosis. OBJECTIVES To analyze(More)
As an alternative to directly targeting of necrotic tissue using hypericin, we synthesized a conjugate of hypericin to biotin for use in a pretargeting approach. With this conjugate, we explored the possibility of a two-step pretargeting strategy using 123I-labeled avidin as effector molecule directed against necrotic RIF-1 tumors. Hypericin was conjugated(More)
In this preclinical study, we examined the biodistribution of hypericin formulated as its water-soluble PVP-hypericin complex in the different layers (urothelium, submucosa, muscle) of a normal rat bladder and a rat bladder bearing a malignant urothelium composed of syngeneic AY-27 tumor cells. The results were compared with the biodistribution of(More)
Farblose, praehtvol l glitzeriide Einkris tal le yon Na~AgO 9 ~nach ZI~TL [1]: hellgrfines Pulver] erhiel ten wir durch Temperi i yon Gemengen 3 NagO + Ag20 [700 ~ Argon, Ag-B6mbchen~. An der Luf t t r i t t sofort Zersetzung ein; es bi ldet sich ein schwarzbranner Brei. Nach Drehkristall, Weissenbergnnd Pr~zess ionsaufnahmen [Mo--K~] liegt eine or(More)