Browsing by Author "Behe, M."

Objective: We performed this pilot study to gain first clinical data of immunoscintigraphy with Tc-99m-labelled anti-NCA-90 antigranulocyte antibody Fab' fragments (Tc-99m-Fab' (LeukoScan(R))) in endocarditis. Patients and methods: Tc-99m-Fab' and echocardiography were used in 24 consecutive patients with suspected endocarditis. Nuclear medicine imaging was performed after i.v. injection of 925 MBq Tc-99m-Fab' fragments and evaluation was done by region of interest (ROI) technique and visually. Results: Seven patients were found to have endocarditis on the basis of the revised Duke criteria, which served as gold standard. Initial scintigraphy was true positive in five patients and false positive in one. In the five true positives, T/B ratios in projection to the heart valve plane (with T/B greater than or equal to1.3+/-0.072) were highly suspicious for florid endocarditis. TTE and TEE were true positive in two and in six patients, whereas false positives were seen in two and in four patients. Scintigraphy was positive in four of the five patients with the false negative TTE and negative in the three false positive TEE. Vice verse, TEE was positive in the two patients with false negative scintigraphy. Conclusions: Immunoscintigraphy with Tc-99m-Fab' fragments in combination with TEE improves diagnostic accuracy compared with TTE/TEE in patients with subacute infective endocarditis. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

Derivatives of somatostatin (sms) are attracting increasing interest as part of the treatment of several cancer diseases expressing sins receptors (srs). Radiolabeled sms analogs can additionally be used for systemic radiotherapy and for diagnostic investigations. Glycosylated sms-14 (sms-dextran(70)) was characterized regarding in vitro srs binding, biodistribution, and blood half-life in mice. Rat brain cortex membranes (expressing srs 2) were used for the srs binding study. Tyr(3)-Octreotide was used as positive control. The binding data were analyzed by competition curve analysis. In the biodistribution study, the Bolton-Hunter reagent was used for the radioiodination of sms-dextran(70). Organs and blood were collected at different time-points and the percentage of the injected dose per gram of tissue (%ID/g) was calculated. The conjugate was administered subcutaneously (sc). The sms-dextran(70) showed high srs binding affinity (i.e., in the same nanomolar range as the reference ligand Tyr(3)-octreotide (IC(50)similar to2.5 nM). The blood half-life was approx 27 h after reaching maximum blood concentration 24 h postinjection. Because of the molecular weight of the conjugate (i.e., approx 75,000) being above the kidney threshold for dextran (i.e., 50,000), the digestion and excretion is assumed to be mainly through the hepatobiliary system. Increased uptake was seen in the adrenals, which are receptor-positive organs. Some accumulation was seen in the stomach, indicating certain deiodination of the conjugate label. The sms-dextran(70) showed promising properties and its clinical relevance is currently being evaluated in clinical phase I-II studies.

Erythropoietin (EPO) is a candidate compound for neuroprotection in human brain disease capable of combating a spectrum of pathophysiological processes operational during the progression of schizophrenic psychosis. The purpose of the present study was to prepare the ground for its application in a first neuroprotective add-on strategy in schizophrenia, aiming at improvement of cognitive brain function as well as prevention/slowing of degenerative processes. Using rodent studies, primary hippocampal neurons in culture, immunohistochemical analysis of human post-mortem brain tissue and nuclear imaging technology in man, we demonstrate that: (1) peripherally applied recombinant human (rh) EPO penetrates into the brain efficiently both in rat and humans, (2) rhEPO is enriched intracranially in healthy men and more distinctly in schizophrenic patients, (3) EPO receptors are densely expressed in hippocampus and cortex of schizophrenic subjects but distinctly less in controls, (4) rhEPO attenuates the haloperidol-induced neuronal death in vitro, and (4) peripherally administered rhEPO enhances cognitive functioning in mice in the context of an aversion task involving cortical and subcortical pathways presumably affected in schizophrenia. These observations, together with the known safety of rhEPO, render it an interesting compound for neuroprotective add-on strategies in schizophrenia and other human diseases characterized by a progressive decline in cognitive performance.

This study investigated the value of fluorine-18 2'-deoxy-2-fluoro-D-glucose (FDG) imaging with a double-headed gamma camera operated in coincidence (hybrid PET) detection mode in patients with suspected spondylitis. Comparison was made with conventional nuclear medicine imaging modalities and magnetic resonance imaging (MRI). Sixteen patients with suspected spondylitis (nine male, seven female, mean age 59 years) prospectively underwent FDG hybrid PET (296 MBq) and MRI. For intra-individual comparison, the patients were also imaged with technetium-99m methylene diphosphonate (MDP) (555 MBq) (n=13) and/or gallium-67 citrate (185 MBq) (n=11). For FDG hybrid PET, two or three transverse scans were performed. Ratios of infected (target) to non-infected (background) (TB) vertebral bodies were calculated. MR images were obtained of the region of interest. Patients found positive for spondylitis with MRI and/or FDG hybrid PET underwent surgical intervention and histological grading of the individual infected foci. Twelve out of 16 patients were found to be positive for spondylitis. Independent of the grade of infection and the location in the spine, all known infected vertebrae (n=23. 9 thoracic. 12 lumbar. 2 sacral) were detected by FDG hybrid PET. T/B ratios higher than 1.45 +/- 0.05 (at 1 h p.i.) were indicative of infectious disease. whereas ratios below this value were found in cases of degenerative change. FDG hybrid PET was superior to MRI in patients who had a history of surgery and suffered from a high-grade infection in combination with paravertebral abscess formation (n=2: further computed tomography was needed) and in those with low-grade spondylitis (n=2, no oedema) or discitis (n=2, mild oedema). False-positive Ga-67 citrate images (n=5: 2 spondylodiscitis, 1 aortitis, 1 pleuritis, 1 pulmonary tuberculosis) and Tc-99m-MDP SPET (n=4: 1 osteoporosis, 2 spondylodiscitis, 1 fracture) were equally well detected by FDG hybrid PET and MRI. No diagnostic problems were seen in the other patients (n=5). In this study, FDG hybrid PET was superior to MRI, Ga-67 citrate and Tc-99m-MDP, especially in patients with low-grade spondylitis (as compared with MRI), adjacent soft tissue infections (as compared with Ga-67 citrate) and advanced bone degeneration (as compared with Tc-99m-MDP).

Gallium-67 citrate is currently considered as the tracer of first choice in the diagnostic workup of fever of unknown origin (FUO). Fluorine-18 2'-deoxy-2-fluoro-D-glucose (FDG) has been shown to accumulate in malignant tumours but also in inflammatory processes. The aim of this study was to prospectively evaluate FDG imaging with a double-head coincidence camera (DHCC) in patients with FUO in comparison with planar and single-photon emission tomography (SPET) Ga-67 citrate scanning. Twenty FUO patients underwent FDG imaging with a DHCC which included transaxial and longitudinal whole-body tomography. In 18 of these subjects, Ga-67 citrate whole-body and SPET imaging was performed. The Ga-67 citrate and FDG images were interpreted by two investigators, both blinded to the results of other diagnostic modalities. Forty percent (8/20) of the patients had infection, 25% (5/20) had auto-immune diseases, 10% (2/20) had neoplasms and 15% (3/20) had other diseases. Fever remained unexplained in 10% (2/20) of the patients. Of the 20 patients studied, FDG imaging was positive and essentially contributed to the final diagnosis in 11 (55%). The sensitivity of transaxial FDG tomography in detecting the focus of fever was 84% and the specificity, 86%. Positive and negative predictive values were 92% and 75%, respectively. Tf the analysis was restricted to the 18 patients who were investigated both with Ga-67 citrate and FDG, sensitivity was 81% and specificity, 86%. Positive and negative predictive values were 90% and 75%, respectively. The diagnostic accuracy of whole-body FDG tomography (again restricted to the aforementioned 18 patients) was lower (sensitivity, 36%; specificity, 86%; positive and negative predictive values, 80% and 46%, respectively). Ga-67 citrate SPET yielded a sensitivity of 67% in detecting the focus of fever and a specificity of 78%. Positive and negative predictive values were 75% and 70%, respectively. A low sensitivity (45%), bur combined with a high specificity (100%), was found in planar Ga-67 imaging. Positive and negative predictive values were 100% and 54%, respectively. It is concluded that in the context of FUO, transaxial FDG tomography performed with a DHCC is superior to Ga-67 citrate SPET. This seems to be the consequence of superior tracer kinetics of FDG compared with those of Ga-67 citrate and of a better spatial resolution of a DHCC system compared with SPET imaging. In patients with FUO, FDG imaging with either dedicated PET or DHCC should be considered the procedure of choice.

We have recently demonstrated that the antiproliferative activity of GnRH-II on human endometrial and ovarian cancer cell lines is not mediated through the GnRH-I receptor. A functional receptor for human GnRH-II has not yet been identified. In this study, we have generated a polyclonal antiserum to the putative human GnRH-II receptor using a peptide (YSPTMLTEVPPC) corresponding to the third extracellular domain coupled to keyhole limpet haemocyanin via the Cys residue. A database search showed no identical peptide sequences in any other human gene. To avoid cross-reactions against two similar amino acid sequences the antiserum was pre-absorbed using these peptides. Immune histological sections of human placenta and human endometrial, ovarian and prostate cancers using rabbit anti-human GnRH-II receptor antiserum showed GnRH-II receptor-like staining. Western blot analysis of cell membrane preparations of human endometrial and ovarian cancer cell lines yielded a band at approximately 43 kDa whereas Western blot analysis of cell membrane preparations of ovaries obtained from the marmoset monkey (Callithrix jacchus) yielded a band at approximately 54 kDa. To identify the GnRH-II receptor-like antigen we used the photo-affinity labelling technique. Photochemical reaction of I-125-labelled (4-azidobenzoyl)-N-hydroxysuccinimide-[D-LyS(6)]-GnRH-II (10(-9) M) with cell membrane preparations of human endometrial and ovarian cancer cells yielded a band at approximately 43kDa. In competition experiments, the GnRH-I agonist Triptorelin (10(-7) M) showed a weak decrease of I-125-labelled (4-azidobenzoyl)-N-hydroxysuccinimide-[D-LyS6]-GnRH-II binding to its binding site. The GnRH-I antagonist Cetrorelix (10(-7) M) showed a clearly stronger decrease, whereas GnRH-II agonist [D-Lys(6)]-GnRH-II (10(-7) M) was the most potent competitor. Western blot analysis of the same gel using rabbit anti-human GnRH-II receptor antiserum identified this band as GnRH-II receptor-like antigen.

BACKGROUND. CD20 has been used successfully as a target molecule for conventional low-dose, as well as high-dose, myeloablative radioimmunotherapy (RIT) of B-cell non-Hodgkin lymphoma (NHL). Mantle cell lymphoma (MCL) is an especially aggressive, prognostically unfavorable subtype of B-cell NHL, associated with an overall 5-year survival rate of less than 20%. Recent evidence has failed to show convincing therapeutic efficacy of conventional, nonmyeloablative RIT in patients with MCL. The aim of this pilot study was to investigate whether high-dose, myeloablative RIT with the iodine-131 (I-131)-labeled chimeric anti-CD20 antibody C2B8 (rituximab, obtained as Mabthera from Roche Pharma, Reinach, Switzerland) is therapeutically effective in MCL patients. METHODS. A total of seven patients with chemorefractory or relapsed MCL were studied in this pilot trial. All had relapsed after high-dose chemotherapy with autologous stem cell transplantation (four of them combined with 12 grays (Gy) total-body irradiation). A diagnostic-dosimetric study was performed with approximately 10 mCi of I-131-labeled C2B8 at a protein dose of 2.5 mg per kg body weight, in order to assess its biodistribution and dosimetry. If splenic pooling was observed, as is typically the case in patients with splenomegaly, the protein dose was doubled in additional studies until a "favorable" biodistribution was obtained. Therapy was performed with myeloablative doses of 261-495 mCi of I-131-labeled C2B8 at the previously optimized protein dose, aiming at lung doses less than or equal to 27 Gy. Homologous stem cell support was provided. Clinical follow-up was obtained at 3-month intervals for up to 38 months (median observation time, 25 months). Overall, in six patients the 2.5 mg/kg protein dose was used, whereas in one patient with splenomegaly, 10 mg/kg was necessary to overcome the splenic antigenic sink. RESULTS. Blood cell nadirs were reached at 2-3 weeks after therapy infusion, but all patients reengrafted at 7-10 days after stem cell reinfusion. Nonhematologic toxicity was restricted to mild-to-moderate nausea, fever, transient bilirubin, or liver enzyme elevations. One patient with preexisting alcoholic cirrhosis experienced a deterioration of liver function. Despite thyroid blocking, 5 of 7 patients developed hypothyroidism, requiring thyroxine substitution at 6-18months after RIT. Six patients experienced a complete and one a good partial remission. Five patients were still in CR at the time this article was written, and six are still alive for more than 3 years; one patient relapsed locally at 3 months and one systemically at 26 months after RIT. CONCLUSIONS. High-dose myeloablative radioimmunotherapy with I-131-labeled anti-CD20 antibodies seems to be associated with a high response rate and moderate toxicity in patients with MCL. Further follow-up to monitor the long-term outcome as well as systematic prospective clinical studies are indicated. Cancer 2002;94:1363-72. (C) 2002 American Cancer Society.

The development of monofunctional DTPA derivatives has been a major breakthrough in the labelling of proteins or peptides with a variety of radiometals. Although this methodology is simple and useful for indium-111 labelling, the stability of these conjugates is too low for most therapeutic nuclides. Cyclic chelators, such as DOTA, have shown excellent kinetic stability with a variety of radiometals, but the labelling procedure is more difficult, requiring ultra-pure reagents and a heating step that sometimes endangers the biomolecule's integrity. The aim of this work was twofold: (a) to develop a novel, open chain chelator which can be easily labelled with various radiometals, displaying higher kinetic stability than monofunctional DTPA, and (b) to evaluate this chelator in vitro and in vivo when conjugated to a CCK-B receptor ligand as a detection modality for receptor-(over-)expressing tumours. DTPA derivatives of Leu(1)- and DGlu(1)-minigastrin were synthesised. All conjugates could be labelled with In-111 or Y-88/90 at high specific activities (8.5-44.4 GBq/mumol) and with high radiochemical purity. Serum stability testing was performed, and the labelled conjugates were compared concerning their stability against DTPA challenge. The biodistribution of the radiolabelled Leu(1)- and DGlu(1)-minigastrin derivatives was studied in tumour-bearing nude mice, in one healthy human volunteer and in three patients with metastatic medullary thyroid carcinoma. The transchelation of all tested radiometals to serum proteins was significantly slower with the DTPA-Glu conjugates as compared with their Leu analogues (e.g. transchelation t(1/2) of DTPA-DGlu(1)-minigastrin vs its Leu(1) analogue at 37degreesC in human serum for In-111: 239 h vs 91 h; for Y-90: 130 h vs 53 h). In animals, all labelled CCK-B receptor ligands showed fast and specific uptake in CCK-B-receptor-positive tissues, such as the stomach and tumour, as well as a fast renal clearance pattern. However, DTPA-Leu(1)-minigastrin showed higher background activity in the whole body and those organs known to accumulate the respective free radiometal (e.g. Y-88-DTPA-Leu(1)-minigastrin had bone uptake of 22%ID/g as compared to only 1.2%ID/g with its DGlu(1) analogue). In humans, fast tumour and stomach uptake was observed for both In-111-labelled compounds, but DTPA-DGlu(1)-minigastrin lacked the liver, spleen and bone marrow uptake observed with its Leu(1) analogue. In conclusion, anionic amino acid derivatives of DTPA may display improved metabolic stability as compared with monofunctional DTPA conjugates. DTPA-DGlu(1)-minigastrin is preferred to 'monofunctional' DTPA-Leu(1)-minigastrin for diagnostic application with In-111 for the in vivo detection of CCK-B receptor-expressing tissues.