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)
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)
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)
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 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)
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)
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)
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)
Hypericin is a potent agent in the photodynamic therapy of cancers and accumulates to a large extent in tumor tissue. To better understand the impact of hypericin aggregates present in the delivery vehicle on the biodistribution of the compound, we compared the in vivo tissue accumulation after administering hypericin suspended as coarse aggregates in(More)