Effective treatment of pancreatic neuroendocrine tumours transfected with the sodium iodide symporter gene by 186Re-perrhenate in mice.

PURPOSE: ReO(4)(-) has similar kinetics regarding the sodium iodide symporter (NIS) to I(-) and TcO(4)(-) in NIS-expressing tissue. We investigated the therapeutic potential of (186)ReO(4)(-) in NIS-transfected neuroendocrine tumour tissue. METHODS: For experiments, the stably NIS-transfected pancreatic neuroendocrine cancer cell line Bon1C was used. NIS-mediated internalization and externalization experiments in vitro and a biodistribution study in nude mice bearing Bon1C xenografts were performed. A therapy study was also conducted consecutively in nude mice xenografted with Bon1C in which the mice were injected intravenously with Na(186)ReO(4). RESULTS: In vitro studies showed exponential internalization and efflux kinetics of (186)ReO(4)(-) in the cell line. The biodistribution study showed high uptake of (186)ReO(4)(-) in NIS-expressing tumours. Tumour growth inhibition was significant after injection of (186)ReO(4) in two groups of animals treated with activity levels below the determined maximum tolerable activity as compared to controls. CONCLUSION: These results indicate that the use of (186)ReO(4)(-) in the treatment of NIS-expressing neuroendocrine tumours is feasible and support the concept of using NIS as a therapeutic target for (186)ReO(4)(-).

Peripheral and central biodistribution of (111)In-labeled anti-beta-amyloid autoantibodies in a transgenic mouse model of Alzheimer's disease.

Active as well as passive immunization against beta-amlyoid (Abeta) has been proposed as a treatment to lower cerebral amyloid burden and stabilize cognitive decline in Alzheimer's disease (AD). To clarify the mechanism of action underlying passive immunization, the in vivo distribution (and sites of degradation) of peripherally administered radiolabeled human and mouse anti-Abeta antibodies were analyzed in a transgenic mouse model of AD. In APP23 mice, a model in which mutated human amyloid precursor protein is overexpressed, the biodistribution of intravenously applicated (111)indium-conjugated affinity-purified human polyclonal autoantibodies (NAbs-Abeta) was compared to that of monoclonal anti-Abeta(1-17) (6E10), anti-Abeta(17-24) antibodies (4G8) and anti-CD-20 (Rituximab), a non-Abeta targeting control. Blood clearance half-lives were 50+/-6h for Rituximab, 20-30h for NAbs-Abeta, 29+/-5h for 4G8 and 27+/-3h for 6E10. Blood activity was higher for 6E10 at 4h as compared to 4G8, Rituximab and NAbs-Abeta. At the 96h time point, Rituximab had the highest blood activity among the antibodies tested. As expected, all antibodies displayed hepatobiliary clearance. Additionally, NAbs-Abeta was excreted in the urinary tract. Liver and kidney uptake of NAbs-Abeta increased over time and was higher than in the monoclonal antibodies at 48h/96h. The brain-to-blood radioactivity ratio for NAbs-Abeta at later time points (>48h) was higher than that of 6E10, 4G8 and Rituximab. In addition, the distribution varied, with highest values found in the hippocampus. Our data indicate a cerebral accumulation of human NAbs-Abeta in the APP23 model. Further studies with human immunoglobulins and particularly with those that recognize different Abeta-epitopes are required in order to delineate in more detail the mode of action of NAbs-Abeta.

Unexpected 99mTc-tetrofosmin findings during myocardial perfusion scintigraphy: intraindividual comparison with PET/computed tomography.

OBJECTIVE: 99mTc-tetrofosmin single photon emission computed tomography (SPECT) is routinely used in the evaluation of coronary artery disease. A variety of different tumors, however, also demonstrate 99mTc-tetrofosmin uptake. We report six patients found with unexpected mediastinal and thoracic tumor uptake during Tc-tetrofosmin myocardial perfusion scintigraphy (MPS). MATERIALS AND METHODS: We investigated 2,155 patients with Tc-tetrofosmin MPS during 2006-2007. One thousand four hundred and eighty-six of these patients had no coronary history and were sent to our department due to newly developed thoracic complaint such as chest pain, dyspnea and others. Six hundred and sixty-nine patients had coronary history. All patients underwent 99mTc-tetrofosmin exercise study. Patients with unexpected extracardiac Tc-tetrofosmin findings during MPS were referred to PET/CT for further diagnostic investigation. Region of interest (ROI; 99mTc-tetrofosmin) and SUVmax (2-[F]fluoro-2-deoxy-D-glucose, F-FDG) were estimated and the results were compared with histological findings. RESULTS: Abnormal mediastinal and/or thoracic activities were visualized in six of the 2,155 patients with 99mTc-tetrofosmin images. Subsequently, the patients underwent resection of a thymoma (n=2), nonsmall cell lung cancer (n=1) and breast cancer (n=3). In the patients with breast cancer one was a male patient with ductal, invasive breast cancer. Benign thymomas showed high 99mTc-tetrofosmin ROI >4.0 and low F-FDG SUVmax <2.0, whereas low 99mTc-tetrofosmin ROI <2.0 were found in nonsmall cell lung cancer and breast cancer and high F-FDG SUVmax >2.5 in these malignant tumors. CONCLUSION: During Tc-tetrofosmin SPECT exercise stress tests performed in patients with suspected coronary artery disease, much more attention must be given to unexpected extracardiac uptakes. With 99mTc-tetrofosmin a large variety of different unknown tumors can be detected during MPS.

Imaging of gastrinomas by nuclear medicine methods.

Somatostatin receptor scintigraphy (SRS) is a valuable method for the detection of somatostatin receptor-positive lesions. Most gastrinomas (over-)express the somatostatin receptor subtype 2 which can be targeted by In-111 labeled Octreotide. Different studies show a high sensitivity of SRS for the localization and staging of gastrinomas. SRS seems to be superior to other non-invasive imaging modalities and has been proven to significantly contribute to patient management. However, the sensitivity depends on the size and exact localization of the tumors. Smaller lesions and lesions located in the duodenum show a significantly lower sensitivity. In any case, SRS belongs to the routine imaging procedure for gastrinomas for localization and staging and can also be used for evaluation of the tumor progression.

Added value of gastrin receptor scintigraphy in comparison to somatostatin receptor scintigraphy in patients with carcinoids and other neuroendocrine tumours.

Gastrin receptor scintigraphy (GRS) is a new imaging method primarily developed for the detection of metastases of medullary thyroid carcinoma (MTC). As gastrin-binding CCK(2) receptors are also expressed on a variety of other neuroendocrine tumours (NET), we compared GRS to somatostatin receptor scintigraphy (SRS) in patients with NET. SRS and GRS were performed within 21 days in a series of 60 consecutive patients with NET. GRS was directly compared with SRS. If lesions were visible on GRS but not detectable by SRS, other imaging modalities (MRI, CT) and follow-up were used for verification. Of the 60 evaluable patients, 51 had carcinoid tumours, 3 gastrinomas, 2 glucagonomas, 1 insulinoma and 3 paragangliomas. The overall tumour-detection rate was 73.7% for GRS and 82.1% for SRS. In the 11 patients with negative SRS, GRS was positive in 6 (54.5%). Based on the number of tumour sites detected and the degree of uptake, GRS performed better than SRS in 13 patients (21.7%), equivalent images were obtained in 18 cases (30.0%) and SRS performed better in 24 (40.0%) cases. In six of the SRS positive patients, 18 additional sites of tumour involvement could be detected. Overall, GRS detected additional tumour sites in 20% of the patients. Localisation of the primary tumours or their functional status had no influence on the outcome of imaging. GRS should be performed in selected patients as it may provide additional information in patients with NET with equivocal or absent somatostatin uptake.

Phase II trial of carcinoembryonic antigen radioimmunotherapy with 131I-labetuzumab after salvage resection of colorectal metastases in the liver: five-year safety and efficacy results.

PURPOSE: Although complete resection (R0) of liver metastases (LM) remains the treatment of choice for colorectal cancer (CRC) patients amenable to curative therapy, only approximately one third survive for 5 years. The objective of this phase II study was to evaluate the safety and efficacy of radioimmunotherapy (RAIT) after salvage resection of LM. PATIENTS AND METHODS: Twenty-three patients who underwent surgery for LM of CRC received a dose of 40 to 60 mCi/m2 of 131I-labetuzumab, which is a humanized monoclonal antibody against carcinoembryonic antigen. Safety (n = 23), disease-free survival (DFS; n = 19), and overall survival (OS; n = 19) were determined. RESULTS: With a median follow-up of 64 months, the median OS time from the first liver resection for RAIT patients was 68.0 months (95% CI, 46.0 months to infinity), and the median DFS time was 18.0 months (95% CI, 11.0 to 31.0 months). The 5-year survival rate was 51.3%. RAIT benefited patients independently of bilobar involvement, size and number of LM, and resection margins. The major adverse effect was transient myelosuppression, resulting mostly in grade < or = 3 neutropenia and/or thrombocytopenia. CONCLUSION: Because both the median OS and 5-year survival rates seem to be improved with adjuvant RAIT after complete LM resection in CRC, compared with historical and contemporaneous controls not receiving RAIT, these results justify further evaluation of this modality in a multicenter, randomized trial.

A new technique for in vivo imaging of specific GLP-1 binding sites: first results in small rodents.

EXPERIMENTAL OBJECTIVES: In vivo imaging of GLP-1 receptor-positive tissues may allow examination of physiologic and pathophysiologic processes. Based on the GLP-1 analog Exendin 4, we have developed a radiolabeled compound specifically targeting the GLP-1 receptor (DTPA-Lys40-Exendin 4). This work aims to detect GLP-1 receptor-positive tissues by biodistribution studies and in vivo small animal imaging studies. For in vivo imaging, a high-resolution multi-pinhole SPECT (single photon emission computed tomography) system was used in conjunction with an MRI (magnetic resonance imaging) system for image fusion. RESULTS: DTPA-Lys40-Exendin 4 can be labeled with 111In to high specific activity (40 GBq/micromol). The radiochemical purity reliably exceeded 95%. Using this compound for in vivo small animal imaging of rats and mice as well as for biodistribution studies, specific GLP-1 binding sites could be detected in stomach, pancreas, lung, adrenals, and pituitary. Receptor-positive tissues were visualized with a high-resolution SPECT system with a resolution of less than 1 mm. CONCLUSIONS: The new technique using DTPA-Lys40-Exendin 4 allows highly sensitive imaging of GLP-1 receptor-positive tissues in vivo. Therefore, intra-individual follow-up studies of GLP-1 receptor-positive tissue could be conducted in vivo.

Two-photon absorption-controlled multidose drug release: a novel approach for secondary cataract treatment.

Tens of millions of cataract surgeries are done every year and the number is increasing heavily. Posterior capsule opacification is the major postoperative complication with an incidence of 10 to 50% within 5 years, depending on the age of the patient. We present a novel approach for secondary cataract treatment in a noninvasive manner. Photochemically triggered drug release from a polymer enables repeated drug applications for cataract treatment years after implantation of the intraocular lens, just when needed. However, light in the visible spectral range must pass through the lens but must not induce drug release. We demonstrate that two-photon absorption photochemistry is a powerful tool to overcome this problem. With wavelengths in the visible regime, a photochemical reaction that requires energies in the UV is triggered. The high intensities needed for this process never occur in any lighting condition in daily lives, but may be easily obtained with focused laser beams routinely used in ophthalmology. The properties of the therapeutic system are specified and the function is demonstrated by in-vitro cell tests. Noninvasive multidose photochemically triggered drug release from implanted intraocular lenses carrying a drug depot may be a therapeutic as well as an economic choice to established treatments of secondary cataracts.

How to successfully implement E-learning for both students and teachers.

RATIONALE AND OBJECTIVES: Electronic learning (e-learning) may provide a means to enhance learning efficacy. However, introduction of e-learning often fails. We describe a strategy of how an e-learning curriculum was successfully implemented. MATERIALS AND METHODS: The curriculum was designed based on published evidence. It consists of self-directed learning, an online discussion forum, and discussion rounds. The e-content in nuclear medicine and radiotherapy was produced by the k-MED team of medical authors, web designers, and psychologists. The online courses were delivered via a dedicated learning management system. The e-content for diagnostic radiology and physics was provided as PDF/HTML script by the respective teachers who objected to participate in the k-MED project. The exam was taken online. Online evaluation of the curriculum by the students was taken at the end of the course. RESULTS: The new curriculum proved very effective. The time for the preparation for the clinical part of the radiology course could be reduced from 4 to 2 weeks. The students particularly enjoyed the self-directed learning. Although the material provided by k-MED received 90%-99% positive scores, the HTML and PDF scripts scored worse (13%-67% positive ratings). The positive results of the evaluation convinced the teachers responsible for physics and diagnostic radiology to participate in k-MED. CONCLUSIONS: As our example shows, new e-learning curricula can successfully be introduced. The strategy of implementation should be based on the existing evidence from the literature. The new curriculum helped to increase the efficacy of teaching and save time as the duration of the respective part of the course could be reduced by half.

Radioiodide treatment after sodium iodide symporter gene transfer is a highly effective therapy in neuroendocrine tumor cells.

This study evaluates the possibility of treating Bon1 and QGP pancreatic neuroendocrine tumor cells with radioactive iodide ((131)I) after stable transfection with the thyroid sodium iodide symporter (NIS). NIS expression was driven either by the strong viral cytomegalovirus promoter or by the tissue-specific chromogranin A promoter. Using either approach, NIS expression was confirmed by reverse transcription-PCR and Western blotting. Uptake of radioactive iodide was increased approximately 20-fold by chromogranin A promoter-driven NIS expression and approximately 50-fold by cytomegalovirus promoter-driven NIS expression. Maximal uptake was reached within 15 min in QGP cells and 30 min in Bon1 cells. Effective half-life was 5 min in QGP and 30 min in Bon1 cells. No evidence of organification was detected by high-performance liquid chromatography and gel filtration chromatography. (131)I was a highly effective treatment in NIS-expressing QGP and Bon1 cells, reducing clone formation by 99.83 and 98.75%, respectively, in the in vitro clonogenic assay. In contrast, clone formation was not reduced in QGP and Bon1 cells without NIS expression after incubation with the same activity concentration of (131)I as compared with mock treated cells. Absorbed doses to QGP and Bon1 cells are up to 150 and 30 Gy, respectively. In addition, a direct cytotoxic effect of radioiodide was demonstrated in NIS-expressing Bon1 cells after (131)I incubation. In conclusion, radioiodide treatment after NIS gene transfer appears to be a promising novel approach in the therapy of neuroendocrine tumors if its highly encouraging in vitro effectiveness can be transferred to the in vivo situation.

Use of polyglutamic acids to reduce uptake of radiometal-labeled minigastrin in the kidneys.

UNLABELLED: Uptake of radiolabeled peptides in the kidneys may obscure abdominal tumors in radiopeptide scintigraphy. This problem is much more pronounced in peptide receptor radionuclide therapy (i.e., radiopeptide therapy), possibly leading to renal damage or even failure. Cationic peptide uptake in the kidneys can be reduced by the application of cationic amino acids, such as lysine or arginine. The aim of this study was to develop a suitable method to reduce anionic peptide uptake in the kidneys. (111)In-Diethylenetriaminepentaacetic acid dGlu(1)-minigastrin ((111)In-DTPA-dGlu-Glu-Glu-Glu-Glu-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH(2)) was chosen as a model compound with a sequence of 6 negatively charged glutamic acids in a chain and an additional aspartic acid. METHODS: TT (human medullary carcinoma cells)-bearing nu/nu mice of the Institute of Cancer Research genotype received intraperitoneal injections of different chain lengths and weights of glutamic acids, aspartic acids, and derivatives of glutamic acids. Uptake in tumors and organs was determined and compared with the values for untreated control mice. RESULTS: Accretion of (111)In-DTPA-dGlu(1)-minigastrin in the kidneys could be reduced by up to 90%. The uptake values for all other organs and the tumors were not affected. These results were obtained with a chain of 5 or more glutamic acids, whereas uptake in kidneys was affected not at all or only slightly with poly-d-glutamic or polyaspartic acids and with Glu(x) (x = 1-4). CONCLUSION: These studies indicated a specific blocking of uptake by Glu(5) sequences in the kidneys. Application of polyglutamic acids is a new, successful method of reducing uptake of negatively charged peptides in the kidneys during radiopeptide therapy.

CCK-2/gastrin receptor-targeted tumor imaging with (99m)Tc-labeled minigastrin analogs.

UNLABELLED: The aim of this study was to evaluate 3 new (99m)Tc-labeled minigastrin analogs modified with open chain tetraamines at the N-terminus for their suitability in the CCK-2/gastrin-R-targeted imaging of tumors (CCK-2/gastrin-R = cholecystokinin subtype 2/gastrin receptor). METHODS: The [(D)Glu(1)]minigastrin sequence was assembled on the solid support and the respective tetraamine precursors coupled at the N-terminus. Purified peptide conjugates were labeled with (99m)Tc under alkaline conditions. Saturation binding experiments were performed for (radio)metallated peptides [(99m)Tc/(99g)Tc]Demogastrin 1-3 in rat acinar pancreatic AR4-2J cell membranes. Internalization was studied in AR4-2J cells at 37 degrees C. Radiopeptide stability was tested in murine plasma, urine, and kidney homogenates. Tissue distribution of the peptides was compared in healthy mice and athymic mice bearing AR4-2J tumors. RESULTS: Peptide conjugates were obtained in 10%-30% overall yields by solid-phase techniques. Radiolabeling afforded >98% pure [(99m)Tc]Demogastrin 1-3 species in specific activities of approximately 37 GBq/mumol. Radiopeptides retained a high affinity for the CCK-2/gastrin-R in vitro (50% inhibitory concentration values of approximately 1 nmol/L) and internalized rapidly in CCK-2/gastrin-R-positive cells. After injection in mice they displayed rapid, high, and specific localization in the CCK-2/gastrin-R-expressing tissues (stomach and AR4-2J tumor) and were excreted from the body via the kidneys in the form of hydrophilic metabolites. CONCLUSION: The promising characteristics of [(99m)Tc]Demogastrin 1-3 both in vitro and in animal models illustrate their suitability for CCK-2/gastrin-R-targeted tumor imaging. These qualities could be confirmed for [(99m)Tc]Demogastrin 2, which provided excellent delineation of tumor deposits in a first patient with metastatic medullary thyroid cancer.

Oligonucleotide microarray for identification of Enterococcus species.

For detection of most members of the Enterococcaceae, the specificity of a novel oligonucleotide microarray (ECC-PhyloChip) consisting of 41 hierarchically nested 16S or 23S rRNA gene-targeted probes was evaluated with 23 pure cultures (including 19 Enterococcus species). Target nucleic acids were prepared by PCR amplification of a 4.5-kb DNA fragment containing large parts of the 16S and 23S rRNA genes and were subsequently labeled fluorescently by random priming. Each tested member of the Enterococcaceae was correctly identified on the basis of its unique microarray hybridization pattern. The evaluated ECC-PhyloChip was successfully applied for identification of Enterococcus faecium and Enterococcus faecalis in artificially contaminated milk samples demonstrating the utility of the ECC-PhyloChip for parallel identification and differentiation of Enterococcus species in food samples.

Sustained activation of nuclear factor kappa B and activator protein 1 in chronic heart failure.

OBJECTIVE: Innate immune response proteins such as inflammatory cytokines, inducible nitric oxide synthase, and toll like receptors are implicated in myocardial depression and left ventricular (LV) remodeling after myocardial infarction (MI). Although all these innate immunity proteins share the downstream activation of the transcription factor NF-kappaB (nuclear factor kappa B) and activator protein 1 (AP-1), the involvement of NF-kappaB and AP-1 in LV remodeling has not been demonstrated so far. METHODS AND RESULTS: Nuclear translocation of NF-kappaB and AP-1 was studied by electrophoretic mobility shift assays and ELISA 10 weeks after large experimental MI in rats, the chronic phase of LV remodeling. In the non-infarcted myocardium of MI rats, NF-kappaB and AP-1 were significantly activated (2.5-fold) as compared to sham-operated animals. Immunohistochemistry demonstrated NF-kappaB activation mainly in cardiac myocytes. Treatment with the ACE (angiotensin converting enzyme) inhibitor trandolapril led to a further 2-fold increase in the activation of NF-kappaB and AP-1 when compared to placebo-treated animals with the same MI size (P<0.001). Human failing hearts explanted at the time of heart transplantation exhibited marked nuclear translocation of NF-kappaB in cardiac myocytes when compared to control hearts. NF-kappaB as well as AP-1 were both significantly activated in congestive heart failure due to ischemic or dilated cardiomyopathy. CONCLUSION: In experimental and human heart failure, both NF-kappaB and AP-1 are chronically activated in cardiac myocytes. These findings suggest an important involvement of NF-kappaB and AP-1 in the cardiac remodeling process.

Vascular endothelial dysfunction and superoxide anion production in heart failure are p38 MAP kinase-dependent.

OBJECTIVE: The mitogen-activated protein (MAP) kinase system, especially the p38 MAP kinase, is activated in chronic heart failure (CHF). However, the role of vascular p38 MAP kinase in CHF has not been analyzed yet. METHODS AND RESULTS: In aortic rings from rats with CHF 10 weeks after myocardial infarction, acetylcholine-induced relaxation was attenuated (maximum relaxation, Rmax: 54+/-5%) compared to sham-operated animals (Rmax: 77+/-5%, p<0.01), while endothelium-independent relaxation elicited by sodium nitroprusside was not significantly changed. Aortic levels of phosphorylated p38 MAP kinase protein were significantly elevated in rats with CHF. In addition, phosphorylation of MAP kinase-activated protein kinase-2 (MAPKAPK-2), an index of p38 MAP kinase activity, was increased. Aortic superoxide anion generation was significantly enhanced in rats with CHF accompanied by elevation of the NAD(P)H oxidase subunit p47phox protein expression. Inhibition of p38 MAP kinase by treatment with the p38 MAP kinase inhibitor SB239063 (800 ppm in standard rat chow) reduced MAPKAPK-2 phosphorylation, preserved acetylcholine-induced relaxation (Rmax: 80+/-4%, p<0.01), and reduced vascular superoxide formation. SB239063 treatment did not affect blood pressure and left ventricular enddiastolic pressure. In aortic tissue from CHF animals treated with the angiotensin-converting enzyme (ACE) inhibitor trandolapril, p38 MAP kinase phosphorylation was significantly reduced. CONCLUSIONS: Vascular p38 MAP kinase is markedly activated in rats with CHF. Chronic p38 MAP kinase inhibition with SB239063 prevented endothelial vasomotor dysfunction through reduction of superoxide anion production.

Eprosartan improves cardiac performance, reduces cardiac hypertrophy and mortality and downregulates myocardial monocyte chemoattractant protein-1 and inflammation in hypertensive heart disease.

OBJECTIVE: The purpose of this investigation was to determine whether angiotensin II receptor (AII1R) antagonism interferes with cardiac monocyte chemoattractant protein-1 (MCP-1) expression in hypertrophic cardiomyopathy and failure. DESIGN: We studied the effects of the AII1R antagonist eprosartan on MCP-1 expression, and on the recruitment of macrophages into the myocardium in a model of cardiac hypertrophy and morbidity/mortality. METHODS: Stroke-prone spontaneously hypertensive rats fed a high-salt, high-fat diet (SFD) developed heart failure characterized by left ventricular (LV) hypertrophy/pathology and hypocontractility. These rats received either normal diet, SFD, or SFD with the daily administration of 30 mg/kg eprosartan for 28 weeks. LV function and wall thickness was assessed by echocardiography, MCP-1 expression was measured by TaqMan real-time polymerase chain reaction, enzyme-linked immunosorbent assay and immunohistochemistry, and macrophage infiltration into the LV was determined by microscopy. RESULTS: Eprosartan reduced the rate of morbidity/mortality (P = 0.001), LV MCP-1 mRNA (P < 0.05) and protein expression (P < 0.01), and LV macrophage infiltration (P < 0.01), while preserving ventricular function (P < 0.05). Eprosartan also produced a moderate (16%; P < 0.05) decrease in blood pressure. CONCLUSIONS: These data demonstrate that AII1R antagonism in an animal model of hypertensive heart disease reduces MCP-1 expression in the myocardium that results in reduced macrophage recruitment. These effects parallel the preservation of LV systolic function and the reduction in cardiac remodeling/disease progression and reduced morbidity/mortality. Suppression of MCP-1 expression might explain in part the beneficial effects of AII1R antagonism in this model.

99mTc-HMPAO-labeled autologous versus heterologous leukocytes for imaging infection.

UNLABELLED: Radiolabeled autologous leukocytes are the gold standard for imaging infectious foci in patients. Good results have also been reported for radiolabeled heterologous leukocytes from noninfected donors. Until now, the 2 methods have not been directly compared. In this study, we compared the infection-imaging potential of 99mTc-hexamethylpropyleneamine oxime (HMPAO)-labeled autologous granulocytes with that of 99mTc-HMPAO-labeled granulocytes from either infected or noninfected donors in rabbits with Escherichia coli infection. METHODS: The radiolabeled granulocyte preparations were studied in rabbits with an E. coli infection in the left calf muscle. The soft-tissue infections were scintigraphically visualized after injection of 18 MBq of either 99mTc-HMPAO purified autologous granulocytes or radiolabeled purified heterologous granulocytes from infected or noninfected donor rabbits. Gamma camera images were acquired at 2 min and at 1, 2, and 4 h after injection. After the last image, the rabbits were killed and uptake of the radiolabel in the dissected tissues was determined. RESULTS: The 99mTc-HMPAO autologous granulocytes and heterologous granulocytes from infected donors accurately revealed the infectious focus in the calf muscle at 2 h after injection. At 4 h after injection, a significantly better (P < 0.05) delineation of the infection was established with the 99mTc-HMPAO autologous granulocytes and 99mTc-HMPAO heterologous granulocytes from the infected rabbits than with the heterologous granulocytes from noninfected donors. With both cell preparations, the intensity of uptake in the infected calf muscle continuously increased until 4 h after injection. The 99mTc-HMPAO heterologous granulocytes from noninfected donors showed no significant increase in contrast after 2 h after injection. Absolute uptake in the infected calf muscle was much higher for 99mTc-HMPAO autologous granulocytes (7.81 +/- 1.21 percentage injected dose [%ID]) and 99mTc-HMPAO heterologous infected granulocytes (8.91 +/- 1.92 %ID) than for the radiolabeled heterologous noninfected granulocytes (2.32 +/- 0.75 %ID) (P < 0.04) at 4 h after injection. The ratio of infected muscle to noninfected contralateral muscle was significantly higher for 99mTc-HMPAO autologous granulocytes and 99mTc-HMPAO heterologous granulocytes from infected donors than for 99mTc-HMPAO heterologous granulocytes from noninfected donors (5.53 +/- 1.09, 3.86 +/- 0.75, and 1.86 +/- 0.31, respectively; P < 0.05). CONCLUSION: For nuclear medicine imaging of infection, purified granulocytes derived from infected rabbits are superior to purified granulocytes derived from noninfected donor rabbits. In addition, autologous granulocytes gave similar results to heterologous granulocytes from infected donor rabbits, suggesting the need for intrinsic cell activation for specific granulocyte migration.

Cholecystokinin-B/Gastrin receptor-targeting peptides for staging and therapy of medullary thyroid cancer and other cholecystokinin-B receptor-expressing malignancies.

The high sensitivity of the pentagastrin stimulation test in detecting primary or metastatic medullary thyroid cancer (MTC) suggests a widespread expression of the corresponding receptor type on human MTC. Indeed, autoradiographic studies demonstrated cholecystokinin (CCK)-B/gastrin receptors not only in more than 90% of MTCs, but also in a high percentage of small-cell lung cancers, stromal ovarian tumors, and potentially a variety of other tumors, including gastrointestinal adenocarcinomas, neuroendocrine tumors, and malignant glioma. The aim of our work was to develop and systematically optimize suitable radioligands for targeting CCK-B receptors in vivo and to investigate their role in the staging and therapy of MTC and other CCK-B receptor expressing malignancies. For this purpose, a variety of CCK/gastrin-related peptides, all having in common the C-terminal CCK-receptor binding tetrapeptide sequence-Trp-Met-Asp-PheNH(2) or derivatives thereof, were investigated. They were members of the gastrin or cholecystokinin families or possessed characteristics of both, which differ by the intramolecular position of a tyrosyl moiety. Their stability and affinity were studied and optimized in vitro and in vivo; their biodistribution and therapeutic efficacy were tested in preclinical models. Best tumor uptake and tumor to nontumor ratios were obtained with members of the gastrin family, because of their superior selectivity and affinity for the CCK-B receptor subtype. Radiometal-labeled derivates of minigastrin showed excellent targeting of CCK-B receptor expressing tissues in animals and healthy human volunteers. Preclinical therapy experiments in MTC-bearing animals showed significant antitumor efficacy. In a subsequent clinical study, 45 MTC patients with metastatic MTC were investigated; 23 had known and 22 had occult disease. CCK-B receptor scintigraphy was performed with (111)In-diethylenetriamine pentaacetic acid-d-Glu(1)-minigastrin. The normal organ uptake was essentially confined to the stomach (and, to a lesser extent, to the gallbladder and, in premenopausal women, to normal breast tissue) as a result of CCK-B receptor specific binding and to the kidneys, as excretory organs. All tumor manifestations known from conventional imaging were visualized as early as 1 hour postinjection, with increasing tumor to background ratios over time; at least 1 lesion was detected in 20 of 22 patients with occult disease (patient-based sensitivity, 91%). Among them were local recurrences and lymph node, pulmonary, hepatic, splenic, and bone (marrow) metastases. Eight patients with advanced metastatic disease were injected in a dose-escalation study with potentially therapeutic activities of a (90)Y-labeled minigastrin derivative at 4 to 6-week intervals (30-50 mCi/m(2) per injection for a maximum of 4 injections). Hematologic and renal toxicities were identified as the dose-limiting toxicities at the 40 and 50 mCi/m(2) levels. Two patients experienced partial remissions, and 4 experienced stabilization of their previously rapidly progressing disease. These data suggest that CCK-B receptor ligands may be a useful new class of receptor-binding peptides for diagnosis and therapy of a variety of (CCK-B receptor expressing) tumor types. They allow for sensitive and reliable staging of patients with metastatic MTC. Initial therapeutic results are promising, but nephrotoxicity is a major concern to be solved.

p38 mitogen-activated protein kinase inhibitors for the treatment of chronic cardiovascular disease.

p38 Mitogen-activated protein kinase (MAPK) has been implicated in cardiovascular disease and is activated by various factors, including neurohormones (e.g., catecholamines, angiotensin II and endothelin), hypoxia and wall stress. Activation of p38 MAPK can cause cardiac hypertrophy, negative inotropy and endothelial dysfunction. All of these conditions lead to chronic cardiovascular disease, which is becoming an ever growing burden on society. p38 MAPK inhibition may therefore be an interesting therapeutic approach to the treatment of various cardiovascular diseases. However, in vitro and in vivo results are conflicting and caution must be applied in the translation of bench results to the clinic.

Imaging lung tumors with peptide-based radioligands.

The somatostatin analogue octreotide was the first radiopeptide to be used for the scintigraphic diagnosis of tumors. Somatostatin receptor scintigraphy (SRS) has proven its value, especially in the detection of gut neuroendocrine tumors. In some tumor types, it is considered the diagnostic gold standard. In carcinoid tumors of the lung, SRS is of major importance in diagnostic workup. Furthermore, the combination of computed tomography scanning and SRS is a reliable and cost-effective approach for the evaluation of single pulmonary nodules. Despite these favorable properties, SRS fails in the detection of metastases of lung cancer. The problem of false-positive results in SRS resulting from inflammatory disease might be overcome by the use of new radiopeptides such as cholecystokinin-B receptor-binding gastrin analogues. This article focuses on the current status of peptide-receptor scintigraphy in the diagnosis of lung tumors and on future developments in this field.