Progress in gene therapy: seeing is believing.
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Gene Expression Regulation, Enzymologic↗
Biomedical subjects
F H Corstens
Publications and source records attributed to F H Corstens.
(99m)Tc-interleukin-8 for imaging acute osteomyelitis.
UNLABELLED: Early and accurate diagnosis of osteomyelitis remains a clinical problem. Acute osteomyelitis often occurs in infants and most often is located in the long bones. Radiologic images show changes only in advanced stages of disease. Scintigraphic imaging with (99m)Tc-methylene diphosphonate (MDP), or bone scanning, is much more sensitive in detecting acute osteomyelitis but lacks specificity. We evaluated the performance of (99m)Tc-interleukin-8 (IL-8) in an experimental model of acute osteomyelitis. METHODS: Acute pyogenic osteomyelitis was induced in 10 rabbits by inserting sodium morrhuate and Staphylococcus aureus into the medullary cavity of the right femur. The cavity was closed with liquid cement. A sham operation was performed on the left femur. Routine radiographs were obtained just before scintigraphy. Ten days after surgery, the rabbits were divided into 2 groups of 5 animals, received an injection of either 18.5 MBq (111)In-granulocytes or 18.5 MBq (67)Ga-citrate, and were imaged both 24 h after injection and 48 h after injection. On day 12, the rabbits received either 18.5 MBq (99m)Tc-MDP or 18.5 MBq (99m)Tc-IL-8, and serial images were acquired at 0, 1, 2, 4, 8, 12, and 24 h after injection. Uptake in the infected femur was determined by drawing regions of interest. Ratios of infected femur (target) to sham-operated femur (background) (T/Bs) were calculated. After the final images were obtained, the rabbits were killed and the right femur was dissected and analyzed for microbiologic and histopathologic evidence of osteomyelitis. RESULTS: Acute osteomyelitis developed in 8 of 10 rabbits. All imaging agents correctly detected the acute osteomyelitis in these animals. The extent of infection was optimally visualized with (67)Ga-citrate and delayed bone scanning, whereas diaphyseal photopenia was noted with both (99m)Tc-IL-8 and (111)In-granulocytes. In 1 rabbit with osteomyelitis, imaging results were falsely negative with (111)In-granulocytes and falsely positive with (99m)Tc-MDP. Quantitative analysis of the images revealed that the uptake in the infected region was highest with (67)Ga-citrate (4.9 +/- 0.8 percentage injected dose [%ID]) and (99m)Tc-MDP (4.7 +/- 0.7 %ID), whereas the uptake in the infected area was significantly lower with (99m)Tc-IL-8 (2.2 +/- 0.2 %ID) and (111)In-granulocytes (0.8 +/- 0.2 %ID) (P < 0.0042). In contrast, the T/Bs were significantly higher for (99m)Tc-IL-8 (T/B, 6.2 +/- 0.3 at 4 h after injection) than for (67)Ga-citrate, (99m)Tc-MDP, and (111)In-granulocytes, which had ratios of 1.5 +/- 0.4, 1.9 +/- 0.2, and 1.4 +/- 0.1, respectively (P < 0.0001). Radiography correctly revealed acute osteomyelitis in only 2 of 8 rabbits. CONCLUSION: In this rabbit model of osteomyelitis, (99m)Tc-IL-8 clearly revealed the osteomyelitic lesion. Although the absolute uptake in the osteomyelitic area was significantly lower than that obtained with (99m)Tc-MDP and (67)Ga-citrate, the T/Bs were significantly higher for (99m)Tc-IL-8 because of fast background clearance. The ease of preparation, good image quality, and lower radiation burden suggest that (99m)Tc-IL-8 may be a suitable imaging agent for the scintigraphic evaluation of acute osteomyelitis.
Animals↗
A 3-step pretargeting strategy to image infection.
UNLABELLED: A new 3-step approach to imaging infectious and inflammatory foci was developed and optimized in a rat model. The approach relies on the nonspecific localization of an anti-diethylenetriaminepentaacetic acid (DTPA) antibody in inflamed tissue. In this study, the 3-step strategy was optimized by selecting the most suitable radiolabeled hapten and tuning the dosing schedule. METHODS: Wistar rats with Staphylococcus aureus infection in the left calf muscle were primed with the anti-DTPA antibody DTIn-1 (0.67, 2, or 6 nmol per rat). In the second step (1-24 h later), the anti-DTPA activity in the circulation was blocked with unlabeled bovine serum albumin DTPA-In (0.3, 1, or 3 nmol per rat). In the third step (5-30 min later), the radiolabeled hapten (monovalent or bivalent 111In-DTPA) was administered. The in vivo distribution of the radiolabel was monitored by scintigraphic imaging and by ex vivo counting of dissected tissues. RESULTS: Scatchard analysis revealed that the affinity of DTIn-1 for bivalent DTPA-111In (111In-diDTPA) was 6 times higher than the affinity for monovalent 111In-DTPA (K(a) = 0.87 x 10(-9) mol/L vs. 5.3 x 10(-9) mol/L). The uptake of the bivalent chelate in the abscess was 2.5-fold higher than that of monovalent 111In-DTPA. Most important, the bivalent chelate was completely retained in the abscess over time. Using the bivalent chelate, the optimal dosing scheme was determined with respect to the DTIn-1 dose (2 nmol per rat), the blocking agent dose (1 nmol per rat), and radiolabeled chelate dose (40 pmol per rat). The procedure was rapid; the infectious focus was clearly visualized 1 h after injection of the 111In-labeled diDTPA, which was 5 h after administration of the anti-DTPA antibody. The nontargeted radiolabel rapidly cleared to the urine, only being retained in the abscess and the kidneys (4-6 percentage injected dose). Finally, an N2S2 core was attached to the diDTPA compound, allowing the use of 99mTc. CONCLUSION: This 3-step approach enables rapid imaging of infectious foci with minimal uptake in noninflamed tissues.
Animals↗
Scintigraphic detection of acute experimental endocarditis with the technetium-99m labelled glycoprotein IIb/IIIa receptor antagonist DMP444.
Bacterial endocarditis is an important clinical problem that may result in persistent bacteraemia and irreversible cardiac damage. Since endocarditis is characterized by aggregation of activated platelets, fibrin and bacteria, we studied DMP444, a technetium-99m labelled high-affinity antagonist of the GP IIb/IIIa receptor that is expressed on activated platelets. In seven Beagle dogs (11-15 kg), the left ventricle was catheterized via the right carotid artery. One hour later, 5x10(7) colony forming units of Staphylococcus aureus were injected intracardially. Half an hour later, the catheter was removed. Two extra dogs underwent a complete sham procedure. One day after the intervention, five infected and the two non-infected dogs were injected with 37 MBq/kg 99mTc-DMP444 and two infected dogs with 37 MBq/kg 99mTc-IgG (used as a non-specific control agent) and imaged up to 4 h after injection. Samples were obtained for tissue counting, microbiology and histology. From 1 to 2 h post injection onward, there was clear focal accumulation of DMP444 in the aortic valve region when endocarditis was present, and this accumulation increased with time. The non-infected and the 99mTc-IgG injected dogs showed only persisting blood pool activity without any focal abnormality. At 4 h post injection, the in vivo valve-to-blood pool ratios were 1.87+/-0.18 in endocarditis, 1.01+/-0.05 in non-infected controls and 1.09+/-0.02 in 99mTc-IgG injected dogs (P<0.05). It is concluded that targeting activated platelets with the 99mTc-labelled GP IIb/IIIa antagonist DMP444 allows a final diagnosis of experimental bacterial endocarditis within 4 h owing to high, specific and fast in vivo uptake.
Acute Disease↗
Radiolabeled liposomes for scintigraphic imaging.
Liposomes have been investigated extensively as carriers for drugs in attempts to achieve selective deposition and/or reduced toxicity. Liposomes radiolabeled with gamma emitters such as (67)Ga, (111)In and (99m)Tc, can be used for imaging purposes. Liposomes as formulated in the past, are rapidly taken up by cells of the mononuclear phagocyte system (MPS), primarily those located in liver and spleen. The recent development of long-circulating liposomes (LCLs), yielded liposomes that oppose recognition by the MPS. The development of these LCLs with enhanced circulatory half-lives has broadened the potential of liposomes to scintigraphically visualize pathologic processes in vivo. Liposomes have been proposed for tumor imaging, infection imaging and blood pool imaging. Strategies have been developed that allow rapid, easy and efficient labeling of preformed liposomes with (111)In and (99m)Tc. There is now a vast body of preclinical evidence showing that LCLs can be used to image a wide variety of tumors as well as inflammatory lesions. The first studies in patients show that radiolabeled liposomes can image tumor and inflammatory lesions with good sensitivity and good specificity. Here, the present status of liposome-based radiopharmaceuticals for scintigraphic application is reviewed.
Animals↗
Clinical significance of low cobalamin levels in older hospital patients.
BACKGROUND: It is still a commonly held belief that many of the frequently found low cobalamin (Cbl, vitamin B12) levels in older people do not represent deficiency and are therefore without clinical significance and should not be treated. In this study this notion will be challenged. METHODS: In this prospective observational cohort design we studied 28 patients aged 65 years and older with low plasma Cbl (< or =150 pmol/l). A number of haematological (Hb, MCV, five- and six-lobed granulocytes), metabolic (plasma levels of methylmalonic acid and homocysteine), and gastrointestinal (plasma pepsinogen A and C and protein-bound and free Cbl absorption) parameters, and the response to Cbl treatment, were measured. Cbl deficiency was considered to be present when at least one of the following three criteria was fulfilled: (1) haematological or metabolic abnormalities compatible with Cbl deficiency; (2) Cbl malabsorption or atrophic gastritis; (3) a response to Cbl supplementation. RESULTS: Haematological or metabolic abnormalities were identified in 27 patients. Atrophic gastritis and Cbl malabsorption were identified in, respectively, 15 and 23 patients. Each treated patient showed a haematological or metabolic response to Cbl supplementation. All patients were considered Cbl deficient: 18 patients (64%) fulfilled three criteria of Cbl deficiency, eight (29%) fulfilled two criteria and two (7%) fulfilled one criterion. CONCLUSIONS: According to the generally accepted and a wide variety of criteria, we found that older patients with low Cbl levels were cobalamin deficient. Therefore, these patients should receive Cbl supplementation.
Aged↗
Early assessment of skeletal muscle damage after ischaemia-reperfusion injury using Tc-99m-glucarate.
PURPOSE: After acute arterial obstruction of the lower extremity, muscle damage is the critical determinant for clinical outcome. The extent of muscle damage and limb viability are currently assessed by clinical examination, which is inaccurate. Tc-99m-pyrophosphate (PYP) has been applied for imaging ischaemia-reperfusion damage. More recently, a new imaging agent, Tc-99m-glucarate (GLUC), was introduced for delineating early myocardial infarction after ischaemia-reperfusion. The aim of this study was to determine if GLUC could delineate early skeletal muscle damage after ischaemia-reperfusion. Both tracers were used in a novel murine model of hindlimb ischaemia-reperfusion. METHODS: In anaesthetised mice, ischaemia of one hindlimb was maintained for 2, 3 and 4h using a tourniquet, followed by a reperfusion period of 1h. Additionally, reperfusion periods of 3, 24 and 96h were studied after 3h of ischaemia. PYP or GLUC was injected 45min before end of reperfusion. Concentrations of both agents were determined in blood, reperfused and contralateral muscle. Reperfused-to-contralateral muscle ratios were calculated. In separate experiments, muscle biopsies were obtained for histologic examination. RESULTS: Ischaemia and reperfusion damage was demonstrated histologically. Using scintigraphy GLUC depicted reperfusion significantly better than PYP. After 2, 3 and 4h of ischaemia, the reperfused-to-contralateral ratios for GLUC were 10.7+/-0.9, 8.9+/-0.9 and 8.6+/-1.1, as compared to 4.5+/-0.7, 4.9+/-0.4 and 4.5+/-0.4 for PYP (P<0.05 at all points). For longer periods of reperfusion, the ratios for GLUC decreased to similar levels as observed for PYP. CONCLUSION: The present study indicates that GLUC is a specific early marker of myocyte necrosis after ischaemia-reperfusion. GLUC may become an useful agent for clinical, early, non-invasive monitoring of skeletal muscle damage after ischaemia-reperfusion.
Animals↗
Labeling proteins with Tc-99m via hydrazinonicotinamide (HYNIC): optimization of the conjugation reaction.
At present there is considerable interest in labeling peptides with Tc-99m for the development of target specific radiopharmaceuticals for imaging purposes. In the present study the conjugation of the bifunctional coupling agent succinimidyl-hydrazinonicotinamide (S-HYNIC) was studied and optimized in a series of peptides [molecular weight (MW) 6.5-14.3 kDa]. Aprotinin (MW 6.5 kDa), cytochrome C (MW 12.4 kDa), alpha-lactalbumin (MW 14.2 kDa), and lysozyme (MW 14.3 kDa) were conjugated with S-HYNIC via the epsilon amino groups of their lysine residues. The effects of molar conjugation ratio, reaction temperature, pH, and protein concentration were studied. Reaction products were analyzed both with respect to the HYNIC-substitution ratio (spectrophotometrically) as well as to the labeling efficiency silica gel-instant thin layer chromatography (SG-ITLC) and molecular size fast performance liquid chromatography (FPLC). The effects of conjugation on biological activity were studied in three proteins binding to receptors on leukocytes: interleukin-8 (MW 8.5 kDa), interleukin-1alpha (MW 17 kDa), and interleukin-1 receptor antagonist (MW 17 kDa). The labeling efficiency of aprotinin, cytochrome c, alpha-lactalbumin, and lysozyme conjugated under optimal conjugation conditions exceeded 90%. Specific activities obtained were up to 7.5 MBq/microg. Conjugation was most efficient at 0 degrees C (as compared to 20 and 40 degrees C), at pH 8.2 (as compared to 6.0, 7.2, and 9.5), and at protein concentrations > or = 2. 5 mg/mL. In general, efficiency increased with increasing molar conjugation ratio (protein-HYNIC-ratio 1:3 < 1:6 < 1:15<1:30). For the receptor binding proteins, biological activity was preserved only under the mildest conjugation conditions. For each of these proteins an inverse relation between labeling efficiency and receptor binding capacity was found. Labeling proteins with (99m)Tc using S-HYNIC is easy, rapid, and efficient, and preparations with high specific activity can be obtained. However, biological activity of proteins may be lost at high HYNIC-substitution ratios. With the proteins tested here a careful balancing of reaction conditions resulted in acceptable, although suboptimal, labeling efficiencies and preservation of biological activity.
Aprotinin↗
Speed of sound reflects Young's modulus as assessed by microstructural finite element analysis.
We analyzed the ability of the quantitative ultrasound (QUS) parameter, speed of sound (SOS), and bone mineral density (BMD), as measured by dual-energy X-ray absorptiometry (DXA), to predict Young's modulus, as assessed by microstructural finite element analysis (muFEA) from microcomputed tomography (muCT) reconstructions. With muFEA simulation, all bone elements in the model can be assigned the same isotropic Young's modulus; therefore, in contrast to mechanical tests, only the trabecular structure plays a role in the determination of the elastic properties of the specimen. SOS, BMD, and microCT measurements were performed in 15 cubes of pure trabecular bovine bone in three orthogonal directions: anteroposterior (AP); mediolateral (ML); and craniocaudal (CC). The anisotropy of the architecture was determined using mean intercept length (MIL) measurements. SOS, MIL, and Young's modulus (E) values were significantly different in all three directions (p < 0.001), with the highest values in the CC direction. There was a strong linear relationship between E and SOS in each of the three orthogonal directions, with r(2) being 0.88, 0.92, and 0.84 (all p < 0.0001) for the CC, ML, and AP directions, respectively. The relationship between E and BMD was less strong, with r(2) being between 0.66 and 0.85 (all p < 0.0001) in the different directions. There was also a significant, positive correlation between SOS and BMD in each of the three axes (r(2) being 0.81, 0.42, and 0.92 in the CC, ML, and AP directions, respectively; p < 0.0001). After correction for BMD, the correlations between SOS and E in each of the three directions remained highly significant (r(2) = 0.77, p < 0. 0001 for the AP direction; r(2) = 0.48, p < 0.001 for the CC direction; r(2) = 0.52, p < 0.005 for the ML direction). After correction for SOS, BMD remained significantly correlated with Young's modulus in the AP and CC directions (r(2) = 0.52, p < 0.005; r(2) = 0.30, p < 0.05, respectively), but the correlation in the ML direction was no longer statistically significant. In a stepwise regression model, E was best predicted by SOS in each of the orthogonal directions. These observations illustrate the ability of the SOS technique to assess the architectural mechanical quality of trabecular bone.
Absorptiometry, Photon↗
Radio-labeled receptor-binding peptides: a new class of radiopharmaceuticals.
Radio-labeled receptor-binding peptides have emerged as an important class of radiopharmaceuticals. In vertebrates, these peptides transmit their biological function by binding to their specific receptor on the target cell surface. This specific receptor-binding property is exploited when the radio-labeled peptide is used as a radiopharmaceutical. The high-binding affinity for its receptor facilitates retention of the peptide in receptor-expressing tissues, whereas its relatively small size facilitates rapid clearance from the blood and other nontarget tissues. Receptor-binding peptides labeled with gamma-emitters can be used to visualize receptor-positive cells in vivo. In addition, when labeled with beta- or alpha-emitters, these peptides can be used for peptide-receptor radionuclide therapy. Various receptors are overexpressed on particular tumor types, and peptides binding to these receptors can be used to visualize tumor lesions scintigraphically. Furthermore, peptides binding receptors on granulocytes can be used to image infectious and inflammatory foci, whereas peptides binding receptors on activated thrombocytes can be used for thrombus imaging. Here, the peptide analogs that are under development for these applications are reviewed.
Animals↗
Pretargeted radioimmunotherapy of non-Hodgkin's lymphoma: best of both worlds?
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Humans↗
Radiolabelled interleukin-1 receptor antagonist for detection of synovitis in patients with rheumatoid arthritis.
OBJECTIVES: To investigate the distribution of radiolabelled interleukin-1 receptor antagonist (IL-1ra) in patients with rheumatoid arthritis (RA) and to assess whether this cytokine is suitable for scintigraphic visualization of synovitis. METHODS: In patients with active RA, scintigraphy was performed after a single i. v. dose of [(123)I]IL-1ra. Clearance and organ distribution of radiolabelled IL-1ra were studied. To assess whether radiolabelled IL-1ra targets the synovial IL-1 receptors, the scintigraphic images obtained with IL-1ra were compared with those obtained by the use of a non-specific control agent. In addition, autoradiography was performed in mice with antigen-induced arthritis that were injected with either radiolabelled IL-1ra or a size-matched, non-receptor-binding protein. RESULTS: Radiolabelled IL-1ra allowed clear visualization of inflamed joints. Specificity in the detection of synovitis was high, whereas a number of painful and swollen joints were not visualized by scintigraphy. The procedure was well tolerated and [(123)I]IL-1ra was rapidly cleared from the circulation (t(1/2)alpha 11 min, t(1/2)beta 612 min) and excreted mainly in the urine. The definition of synovial contours by IL-1ra scintigraphy was not better than that observed with a non-specific agent. Although radiolabelled IL-1ra retained its affinity for IL-1 receptors, no binding to synovium was observed by autoradiography. CONCLUSIONS: Radiolabelled IL-1ra allows the visualization of synovitis in patients with RA. However, neither the imaging nor the autoradiographic studies indicate that joint accumulation of radiolabelled IL-1ra is due to specific IL-1 receptor targeting. IL-1ra has proved its therapeutic value in RA, but with the dose schedule in this study it does not behave as a specific radiopharmaceutical that is suitable for scintigraphic detection of inflammation.
Adult↗
A 99Tcm-labelled leukotriene B4 receptor antagonist for scintigraphic detection of infection in rabbits.
In a search for a rapid and accurate imaging agent for scintigraphic detection of infection and inflammation, an LTB4 receptor antagonist, 99Tcm-RP517, which contains the hydrazino nicotinamide moiety, has been developed recently. To study the in vivo behaviour of 99Tcm-RP517, rabbits with Escherichia coli infection were injected intravenously with 99Tcm-RP517. Gamma camera images were obtained and ex vivo bio-distribution was determined at several hours post-injection (p.i.). In a separate set of rabbits the choledochal duct was cannulated to quantitatively monitor the hepatobiliary clearance of the radiopharmaceutical. The receptor binding fraction of the radiolabelled RP517 exceeded 70%. Accumulation of 99Tcm-RP517 in the abscess was visualized as early as 1 h p.i. Due to rapid blood clearance (t1/2 alpha=18+/-0.6 min, t1/2 beta=6.5+/-0.4 h) and high abscess uptake, the abscess-to-muscle ratios increased with time from 7.0+/-2.3 at 1 h p.i. to 44.3+/-4.6 at 20 h p.i. The agent mainly cleared via the hepatobiliary route: 50% of the radiolabel was recovered in the small bowel at 1 h p.i., whereas 85% was found in cecum and sigmoid at 20 h p.i. In conclusion, 99Tcm-RP517 rapidly visualized E. coli abscesses in rabbits. The agent rapidly cleared from the blood, mainly via the hepatobiliary route. High abscess-to-background ratios were achieved. The accumulation in the intestines could limit the applicability of this agent for detecting infectious processes in the abdominal area. The development of a more hydrophilic analogue of 99Tcm-RP517 could improve the clinical applicability of this agent.
Acute Disease↗
Tc-99m-PEG-Liposomes for the evaluation of colitis in Crohn's disease.
In the present study, the potential role of 99mTc-PEG-liposome to determine the extent and severity of active disease of Crohn's colitis was investigated. Patients suspected of having an exacerbation of Crohn's disease underwent a 99mTc-PEG-liposome scan (740 MBq, imaging at 4 and 24 h p.i.). A barium enema or endoscopy was performed as the standard verification procedure. Disease activity indices (Clinical Disease Activity Index and Van Hees Activity Index) were calculated. In seven patients positive images of colon segments affected by Crohn's colitis were obtained using 99mTc-PEG-liposomes. Only a moderate relation between 99mTc-liposome scan grading and verification procedures was found (Spearman rank r = 0.22). In accordance with previous studies, no significant correlation was found between the clinical disease activity indices and the verification procedures. This study was prematurely terminated because of unacceptable side-effects in 3 out of 9 patients, which occured almost immediately after starting the infusion. The complaints consisted of dyspnea and facial erythema. The symptoms were self-limiting when the infusion was stopped. In conclusion, the extent of Crohn's colitis can be established non-invasively with 99mTc-PEG-liposome scintigraphy. However, in view of the encountered side-effects, the PEG-liposomal preparation may have to be modified.
Adult↗
Accelerated blood clearance and altered biodistribution of repeated injections of sterically stabilized liposomes.
Sterically stabilized liposomes are considered promising carriers of therapeutic agents because they can facilitate controlled release of the drugs, thereby reducing drug-related toxicity and/or targeted delivery of drugs. Herein, we studied the pharmacokinetics and biodistribution of repeated injections of radiolabeled polyethyleneglycol (PEG) liposomes. Weekly injections of (99m)Tc-PEG liposomes dramatically influenced the circulatory half-life in rats. Biodistribution 4 h after the second dose showed a significantly reduced blood content (from 52.6 +/- 3.7 to 0.6 +/- 0.1% injected dose (ID), P <.01) accompanied by a highly increased uptake in the liver (from 8.1 +/- 0.8 to 46.2 +/- 9.8%ID, P <.01) and in the spleen (from 2.2 +/- 0.2 to 5.3 +/- 0.7%ID, P <.01). At subsequent injections the effect was less pronounced: after the fourth dose, the pharmacokinetics of the radiolabel had almost returned to normal. The same phenomenon was observed in a rhesus monkey, but not in mice. The enhanced blood clearance of the PEG liposomes also was observed in rats after transfusion of serum from rats that had received PEG liposomes 1 week earlier, indicating that the enhanced blood clearance was caused by a soluble serum factor. This serum factor was a heat-labile molecule that coeluted on a size exclusion column with a 150-kDa protein. In summary, i.v. administration of sterically stabilized PEG liposomes significantly altered the pharmacokinetic behavior of subsequently injected PEG liposomes in a time- and frequency-dependent manner. The observed phenomenon may have important implications for the repeated administration of sterically stabilized liposomes for targeted drug delivery.
Animals↗
Imaging acute appendicitis: an opportunity for nuclear medicine in the surgical emergency room.
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Acute Disease↗
Radiolabeled interleukin-8: specific scintigraphic detection of infection within a few hours.
UNLABELLED: Several small receptor-binding agents have been tested for imaging of infection and inflammation. The potential of chemotactic peptides and of interleukins is promising and superior to that of conventional agents. In this study, we investigated the potential of interleukin-8 (IL-8) to image infection in rabbits. METHODS: IL-8 was labeled with 123I using the Bolton-Hunter method. Twenty-fours hours after induction of Escherichia coli abscesses in the left thigh muscle, rabbits were injected intravenously with 18.5 MBq 123I-IL-8. Gamma camera images were obtained at 5 min and at 1, 4, and 8 h after injection. Biodistribution was determined 8 h after injection. RESULTS: 123I-IL-8 rapidly cleared from the blood. Accumulation of 123I-IL-8 in the abscess was visible as early as 1 h after injection. The highest abscess uptake was obtained 4 h after injection (2.6+/-0.2 percentage injected dose [%ID]), whereas 123I-IL-8 rapidly cleared from all other tissues. This resulted in increases in abscess-to-background ratios to 13.0+/-0.7 (8 h after injection), as determined by quantification of the images. In tissue biodistribution (8 h after injection), the abscess uptake was 0.057+/-0.011 %ID/g with abscess-to-contralateral muscle ratios of 114.7+/-23.0. The radioiodination method clearly affected the in vivo biodistribution of IL-8 because IL-8 iodinated using the lodo-Gen method cleared significantly slower from the blood and most other organs, resulting in poor visualization of the abscess. CONCLUSION: The superior characteristics of IL-8 radioiodinated using the Bolton-Hunter method--i.e., high abscess uptake and rapid background clearance within a few hours--make IL-8 a promising agent to image infection and inflammation.
Abscess↗
99mTc-PEG liposomes for the scintigraphic detection of infection and inflammation: clinical evaluation.
UNLABELLED: Polyethyleneglycol (PEG) liposomes have been shown to be excellent vehicles for scintigraphic imaging of infection and inflammation in various experimental models. In this article we report on a series of patients with possible infectious and inflammatory disease in whom the performance of 99mTc-PEG liposomes was evaluated. The results of 99mTc-PEG liposome scintigraphy were directly compared with those of 111In-immunoglobulin G (IgG) scintigraphy. METHODS: Thirty-five patients (22 men, 13 women; mean age, 51 y; range, 20-76 y), suspected of having infectious or inflammatory disease, received 740 MBq 99mTc-PEG liposomes intravenously. Imaging was performed at 4 and 24 h after injection. Patients received 75 MBq 111In-IgG 24 h after administration of the liposomes. The scintigraphic results were compared and verified by culture, biopsy, surgery, and follow-up of at least 6 mo. RESULTS: Of the 16 proven infections and inflammations, 15 were detected by 99mTc-PEG liposome scintigraphy: soft-tissue infection (n = 3), septic arthritis (n = 3), autoimmune polyarthritis (n = 2), infected hip prosthesis (n = 1), infected osteosynthesis (n = 1), spondylodiscitis (n = 1), infected aortic prosthesis (n = 1), colitis (n = 1), abdominal abscess (n = 1), and pneumonia (n = 1). 99mTc-PEG liposome and 111In-IgG scintigraphy both missed 1 case of endocarditis. In addition, an 111In-IgG scan of a patient with mild soft-tissue infection was false-negative. Concordantly false-positive scans were recorded from 2 patients, both with uninfected pseudarthrosis and focal signs of sterile inflammation. During liposomal administration, 1 patient experienced flushing and chest tightness, which rapidly disappeared after lowering the infusion rate. No other adverse events were observed. CONCLUSION: This clinical evaluation of 99mTc-PEG liposomes shows that focal infection and inflammation can be adequately imaged with this new agent. The performance of 99mTc-PEG liposomes is at least as effective as that of 111In-IgG. With the simple and safe preparation and the physical and logistic advantages of a 99mTc label, 99mTc-PEG liposomes could be an attractive agent for infection or inflammation imaging.
Female↗