Integrated transcriptomic and metabolomic analysis reveals the potential mechanisms underlying indium-induced inhibition of root elongation in wheat plants

Soil contamination by indium, an emerging contaminant from electronics, has a negative impact on crop growth. Inhibition of root growth serves as a valuable biomarker for predicting indium phytotoxicity. Therefore, elucidating the molecular mechanisms underlying indium-induced root damage is essential for developing strategies to mitigate its harmful effects. Our transcriptomic findings revealed that indium affects the expression of numerous genes related to cell wall composition and metabolism in wheat roots. Morphological and compositional analysis revealed that indium induced a 2.9-fold thickening and a 17.5 % increase in the content of cell walls in wheat roots. Untargeted metabolomics indicated a substantial upregulation of the phenylpropanoid biosynthesis pathway. As the major end product of phenylpropanoid metabolism, lignin significantly accumulated in root cell walls after indium exposure. Together with increased lignin precursors, enhanced activity of lignin biosynthesis-related enzymes was observed. Moreover, analysis of the monomeric content and composition of lignin revealed a significant enrichment of p-hydroxyphenyl (H) and syringyl (S) units in root cell walls under indium stress. The present study contributes to the existing knowledge of indium toxicity. It provides valuable insights for developing sustainable solutions to address the challenges posed by electronic waste and indium contamination on agroecosystems.

Activating Silent Synapses in Sulfurized Indium Selenide for Neuromorphic Computing

The transformation from silent to functional synapses is accompanied by the evolutionary process of human brain development and is essential to hardware implementation of the evolutionary artificial neural network but remains a challenge for mimicking silent to functional synapse activation. Here, we developed a simple approach to successfully realize activation of silent to functional synapses by controlled sulfurization of chemical vapor deposition-grown indium selenide crystals. The underlying mechanism is attributed to the migration of sulfur anions introduced by sulfurization. One of our most important findings is that the functional synaptic behaviors can be modulated by the degree of sulfurization and temperature. In addition, the essential synaptic behaviors including potentiation/depression, paired-pulse facilitation, and spike-rate-dependent plasticity are successfully implemented in the partially sulfurized functional synaptic device. The developed simple approach of introducing sulfur anions in layered selenide opens an effective new avenue to realize activation of silent synapses for application in evolutionary artificial neural networks.

Role of pH on indium bioaccumulation by Chlamydomonas reinhardtii

For divalent metals, the Biotic Ligand Model (BLM) has been proven to be an effective tool to predict biological effects by taking into account speciation calculations and competitive interactions. Nonetheless, the BLM has only rarely been validated for trivalent metals (e.g. rare earth elements), and the potential competitive effects of protons has been understudied. In this paper, the short-term biouptake of indium (In), a trivalent metal that is a byproduct of zinc extraction and used in numerous applications including the semiconductor industry, was evaluated under controlled conditions. Short-term (i.e. 60 min) indium biouptake by Chlamydomonas reinhardtii was measured as a function of pH in order to verify the validity of the BLM. At a given pH, In biouptake could be well described by the Michaelis-Menten equation with conditional stability constants of K_In,pH=4.0 = 10^6.7 M^-1, K_In,pH=5.0 = 10^8.6 M^-1, K_In,pH=6.0 = 10^9.3 M^-1 and maximum internalization fluxes of J_{max, pH=4.0} = 0.74 × 10^-14 mol cm^-2 s^-1, J_{max, pH=5.0} = 1.60 × 10^-14 mol cm^-2 s^-1, J_{max, pH=6.0} = 2.22 × 10^-14 mol cm^-2 s^-1. Although several potential mechanisms for the role of pH were examined, the results were best explained by a competitive interaction of H⁺ with the In uptake sites using overall stability constants of logK_In = 9.76 M^-1 and logK_H = 15.66 M^-1. Based on these results, pH will play a critical role in bioavailability measurements of the trivalent cations in natural waters.

Leaching of indium from end-of-life LCD panels via catalysis by synergistic microbial communities

Currently, a large amount of discarded liquid crystal displays (LCDs) are being produced, and the improper treatment of discarded LCDs causes serious environmental pollution problems. Indium is the most valuable metal in LCDs and is present in such devices at a concentration of over 0.025%. In this study, the bioleaching of indium from end-of-life LCD panels was comprehensively investigated through three methods: S-mediated pathway, Fe-mediated pathway and Mixed pathway of S- and Fe-mediated, which yielded maximum bioleaching efficiencies of approximately 100%, 0% and 78%, respectively. Microbial community analysis showed that the dominant functional bacteria under the S-mediated pathway were Acidithiobacillus. The Acidithiobacillus genus catalysed the leaching of indium, which was mainly achieved by indirect bioleaching. In addition, the microorganisms can secrete enzymes and extracellular polymeric substances, which also contributed to the leaching of indium. Therefore, this work provides an economical and efficient biological method for future research and practical applications in indium recovery from solid waste.

The role of lysosomes in the phenomenon of concentration of aluminum and indium in the female reproductive system. An ultrastructural study

The female reproductive system is one of the most complex systems in the body taking into account the hormonal fluctuations associated with ovarian and uterine menstrual cycles. The purpose of this work was to study the impact of aluminum nitrate and indium sulfate on the uterus and the ovary of a pregnant rat. The experiment was performed on adult female rats of Wistar strain weighing approximately 250g. The Transmission Electron Microscopy (TEM) showed the presence of electron-dense material in lysosomes of both uterine cells (myometrium and endometrium cells) and in the cells of the ovary (internal theca and granulosa cells). In addition to the presence of aluminum and indium deposits in the uterine and ovarian tissue, impaired endoplasmic reticulum, mitochondria and vacuolation were also identified. We concluded that lysosomes of uterus and ovary cells had the function to extract aluminum and indium introduced into the body in a soluble form. Then, the two elements were sequestrated within these organelles in an insoluble form most probably as phosphate salts such as reported for other kind of cells; kidney, liver, bone morrow Berry, 1996 [1]. This mechanism seems to be a defense one in which the lysosome would play a central role. Our results concerning the impact of the aluminum or indium presence in the lysosome of female reproductive system will be further used in order to assess their effects on the fertility and viability of oocytes in the pregnant treated rats.

Complexes of gastrin with In3+, Ru3+ or Ga3+ ions are not recognised by the cholecystokinin 2 receptor

The peptide hormone gastrin (Gamide) binds trivalent metal ions, including indium (In), ruthenium (Ru) and gallium (Ga), with high affinity. Complexes of gastrin with chelated isotopes of In and Ga have previously been used for the location of tumours expressing the cholecystokinin 2 receptor (CCK2R). The aim of the present study was to purify the complexes of Gamide with radioactive isotopes of In, Ru or Ga and to investigate their ability to bind to the CCK2R. The radioactive Gamide complexes were purified on Sep-Pak C18 cartridges or by anion exchange HPLC. Binding to the CCK2R was assessed with a stably transfected clone of the gastric carcinoma cell line AGS. The ¹⁰⁶Ru-Gamide complex could be eluted from the C18 cartridge; the ¹¹¹In-Gamide and ⁶⁸Ga-Gamide complexes bound irreversibly. All three complexes were successfully purified by anion exchange HPLC. The failure to detect binding of the ¹¹¹In-Gamide, ¹⁰⁶Ru-Gamide and ⁶⁸Ga-Gamide complexes to the CCK2R suggests that formation of these complexes will not be useful for the detection of tumours expressing this receptor, but may instead provide alternative ways to block the actions of Gamide as a growth factor or a stimulant of gastric acid secretion. The complexes between the hormone gastrin and radioactive ¹¹¹In, ¹⁰⁶Ru or ⁶⁸Ga ions were purified by anion exchange HPLC using a NaCl gradient. The failure to detect binding of the complexes to the cholecystokinin 2 receptor suggests that metal ion treatment may provide novel approaches to block the biological actions of gastrin.

Facile Synthesis of Cadmium-Free Zn-In-S:Ag/ZnS Nanocrystals for Bio-Imaging

High quality cadmium-free Zn-In-S:Ag doped-nanocrystals (d-NCs) were synthesized via a simple one-step noninjection route using silver nitrate, indium acetate, zinc acetate, oleylamine, S powder and 1-dodecanethiol as starting materials in an organic phase. The size and optical properties can be effectively tailored by controlling the reaction time, reaction temperature, Ag(+) dopant concentration, and the molar ratio of In to Zn. The photoluminescence wavelength of as-prepared Zn-In-S:Ag NCs covered a broad visible range from 458 nm to 603 nm. After being passivated by protective ZnS shell, the photoluminescence quantum yield (PLQY) of Zn-In-S:Ag(+) /ZnS was greatly improved to 43.5%. More importantly, the initial high PLQY of the obtained core/shell d-NCs in organic media can be preserved when being transferred into the aqueous media via ligand exchange. Finally, high quality Zn-In-S:Ag(+) /ZnS d-NCs in aqueous phase were applied as bio-imaging agents for identifying living KB cells.

Evaluation of Nonferrous Metals as Potential In Vivo Tracers of Transferrin-Based Therapeutics

Transferrin (Tf) is a promising candidate for targeted drug delivery. While development of such products is impossible without the ability to monitor biodistribution of Tf-drug conjugates in tissues and reliable measurements of their levels in blood and other biological fluids, the presence of very abundant endogenous Tf presents a significant impediment to such efforts. Several noncognate metals have been evaluated in this work as possible tracers of exogenous transferrin in complex biological matrices using inductively coupled plasma mass spectrometry (ICP MS) as a detection tool. Placing Ni(II) on a His-tag of recombinant Tf resulted in formation of a marginally stable protein-metal complex, which readily transfers the metal to ubiquitous physiological scavengers, such as serum albumin. An alternative strategy targeted iron-binding pockets of Tf, where cognate Fe(III) was replaced by metal ions known to bind this protein. Both Ga(III) and In(III) were evaluated, with the latter being vastly superior as a tracer (stronger binding to Tf unaffected by the presence of metal scavengers and the retained ability to associate with Tf receptor). Spiking serum with indium-loaded Tf followed by ICP MS detection demonstrated that protein quantities as low as 0.04 nM can be readily detected in animal blood. Combining laser ablation with ICP MS detection allows distribution of exogenous Tf to be mapped within animal tissue cross-sections with spatial resolution exceeding 100 μm. The method can be readily extended to a range of other therapeutics where metalloproteins are used as either carriers or payloads. Graphical Abstract ᅟ.

High Affinity Binding of Indium and Ruthenium Ions by Gastrins

The peptide hormone gastrin binds two ferric ions with high affinity, and iron binding is essential for the biological activity of non-amidated forms of the hormone. Since gastrins act as growth factors in gastrointestinal cancers, and as peptides labelled with Ga and In isotopes are increasingly used for cancer diagnosis, the ability of gastrins to bind other metal ions was investigated systematically by absorption spectroscopy. The coordination structures of the complexes were characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. Changes in the absorption of gastrin in the presence of increasing concentrations of Ga³⁺ were fitted by a 2 site model with dissociation constants (K_d) of 3.3 x 10⁻⁷ and 1.1 x 10⁻⁶ M. Although the absorption of gastrin did not change upon the addition of In³⁺ ions, the changes in absorbance on Fe³⁺ ion binding in the presence of indium ions were fitted by a 2 site model with K_d values for In³⁺ of 6.5 x 10⁻¹⁵ and 1.7 x 10⁻⁷ M. Similar results were obtained with Ru³⁺ ions, although the K_d values for Ru³⁺ of 2.6 x 10⁻¹³ and 1.2 x 10⁻⁵ M were slightly larger than observed for In³⁺. The structures determined by EXAFS all had metal:gastrin stoichiometries of 2:1 but, while the metal ions in the Fe, Ga and In complexes were bridged by a carboxylate and an oxygen with a metal-metal separation of 3.0–3.3 Å, the Ru complex clearly demonstrated a short range Ru—Ru separation, which was significantly shorter, at 2.4 Å, indicative of a metal-metal bond. We conclude that gastrin selectively binds two In³⁺ or Ru³⁺ ions, and that the affinity of the first site for In³⁺ or Ru³⁺ ions is higher than for ferric ions. Some of the metal ion-gastrin complexes may be useful for cancer diagnosis and therapy.

High prevalence of upper urinary tract involvement detected by 111indium-oxine leukocyte scintigraphy in patients with candiduria

The purpose of this investigation was to assess the prevalence of upper urinary tract involvement in patients with candiduria by means of (111)indium-oxine-labeled leukocyte scintigraphy. An observational cohort study of patients with confirmed candiduria was conducted in an acute-care teaching hospital in Spain from March 2006 through February 2009. An (111)In-labeled leukocyte scan was performed in order to assess the upper urinary tract involvement. A series of non-matched patients without candiduria nor bacteriuria undergoing scintigraphy to exclude infections in other sites than the urinary tract was also studied. Demographics, baseline illness, and clinical data were recorded. Candiduria was detected in 428 patients, and scintigraphy was performed in 35 of these patients. Twenty-nine patients without candiduria nor bacteriuria were also studied. Positive renal scintigraphy was documented in 24 (68%) patients with confirmed candiduria and in 3 (10%) patients without candiduria (p < 0.005). Renal uptake was not associated with a higher mortality nor with re-admissions. Subclinical pyelonephritis could be more frequent in patients with candiduria than it has been previously considered.

Cell-permeable Ln(III) chelate-functionalized InP quantum dots as multimodal imaging agents

Quantum dots (QDs) are ideal scaffolds for the development of multimodal imaging agents, but their application in clinical diagnostics is limited by the toxicity of classical CdSe QDs. A new bimodal MRI/optical nanosized contrast agent with high gadolinium payload has been prepared through direct covalent attachment of up to 80 Gd(III) chelates on fluorescent nontoxic InP/ZnS QDs. It shows a high relaxivity of 900 mM(-1) s(-1) (13 mM(-1 )s(-1) per Gd ion) at 35 MHz (0.81 T) and 298 K, while the bright luminescence of the QDs is preserved. Eu(III) and Tb(III) chelates were also successfully grafted to the InP/ZnS QDs. The absence of energy transfer between the QD and lanthanide emitting centers results in a multicolor system. Using this convenient direct grafting strategy additional targeting ligands can be included on the QD. Here a cell-penetrating peptide has been co-grafted in a one-pot reaction to afford a cell-permeable multimodal multimeric MRI contrast agent that reports cellular localization by fluorescence and provides high relaxivity and increased tissue retention with respect to commercial contrast agents.

Synthesis and characterization of dual function vanadyl, gallium and indium curcumin complexes for medicinal applications

Novel bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione (curcumin) complexes with the formula, ML(3), where M is Ga(III) or In(III), or of the formula, ML(2) where M is [VO](2+), have been synthesized and characterized by mass spectrometry, infrared and absorption spectroscopies, and elemental analysis. A new ligand, bis[4-acetyl-3-hydroxyphenyl]-1,6-heptadiene-3,5-dione (diacetylbisdemethoxycurcumin, DABC) was similarly characterized; an X-ray structure analysis was performed. Vanadyl complexes tested in an acute i.p. testing protocol in STZ-diabetic rats showed a lack of insulin enhancing potential. Vanadyl complexes were, however, more cytotoxic than were the ligands alone in standard MTT (3-[4,5-dimethylthiazole-2-yl]ate, -2,5-diphenyl-tetrazolium bromide) cytotoxicity testing, using mouse lymphoma cells. With the exception of DABC, that was not different from VO(DABC)(2), the complexes were not significantly different from one another, with IC(50) values in the 5-10 microM range. Gallium and indium curcumin complexes had IC(50) values in the same 5-10 microM range; whereas Ga(DAC)(3) and In(DAC)(3) (where DAC=diacetylcurcumin) were much less cytotoxic (IC(50)=20-30 microM). Antioxidant capacity was decreased in VO(DAC)(2), Ga(DAC)(3), and In(DAC)(3), compared to vanadyl, gallium and indium curcumin, corroborating the importance of curcumin's free phenolic OH groups for scavenging oxidants, and correlated with reduced cytotoxic potential.

An indium:calcium phosphate colloid that specifically targets fibrin

The ability of indium to target fibrin in vitro was evaluated. The radionuclide (114m)Indium (114mIn) was prepared as a soluble and colloidal (In:In) form, as well as, a mixed indium:calcium phosphate (In:CaP) colloid. Soluble 114mIn was prepared by maintaining acid pH (50 mM HCl). Colloidal 114mIn (In:In) was prepared under slightly basic conditions (50 mM Tris-Cl, pH 7.6). The mixed In:CaP colloid was prepared by incubation of 114mIn with calcium (10 mM) and phosphate (250 microM) under slightly basic conditions (50 mM Tris-Cl, pH 7.6). To assess fibrin binding, the three 114mIn preparations were mixed with diluted human plasma (source of fibrinogen). Fibrin polymerization was initiated by addition of calcium (5 mM) and thrombin (0.5 U/ml). Following incubation (15 min, 37 degrees C), the fibrin matrix was condensed, removed from the reaction mixture, and washed briefly. Fibrin uptake of 114mIn (soluble, colloidal, or In:CaP) was determined by gamma counting. Results demonstrated that soluble 114mIn exclusively bound a plasma protein electrophoretically and immunologically identified as transferrin. Although both colloidal 114mIn and 114mIn:CaP bound fibrin, the mixed 114mIn:CaP colloid demonstrated substantially higher fibrin binding activity (about 2-fold). The target of indium binding was confirmed as fibrin due to the presence of characteristic cross-linked gamma-gamma dimers (100 kDa) and beta-monomers (58 kDa) by SDS-PAGE. 114mIn colloid and the mixed 114mIn:CaP colloid demonstrated no ability to bind fibrin's precursor, fibrinogen. 114mIn:CaP fibrin binding was associated with formation of CaP, as evidenced by its dependence on phosphate concentration. The biocompatibility of CaP including its ability to bind 114mIn and specifically target fibrin may be of potential value for diagnostic imaging studies to identify regions of occult vascular stenosis (i.e., atherosclerotic plaques, deep vein thrombosis, pulmonary embolus).

Indirect detection of protein-metal binding: interaction of serum transferrin with In3+ and Bi3+

Transferrins comprise a class of monomeric glycoproteins found in all vertebrates, whose function is iron sequestration and transport. In addition to iron, serum transferrin also binds a variety of other metals and is believed to provide a route for the in vivo delivery of such metals to cells. In the present study, ESI MS is used to investigate interactions between human serum transferrin and two nonferrous metals, indium (a commonly used imaging agent) and bismuth (a component of many antiulcer drugs). While the UV-Vis absorption spectroscopy measurements clearly indicate that both metals bind strongly to transferrin in solution, the metal-protein complex can be detected by ESI MS only for indium, but not for bismuth. Despite the apparently low stability of the transferrin-bismuth complex in the gas phase, presence of such complex in solution can be established by ESI MS indirectly. This is done by monitoring the evolution of charge state distributions of transferrin ions upon acid-induced protein unfolding in the presence and in the absence of the metal in solution. The anomalous instability of the transferrin-bismuth complex in the gas phase is rationalized in terms of conformational differences between this form of transferrin and the holo-forms of this protein produced by binding of metals with smaller ionic radii (e.g., Fe3+ and In3+). The large size of Bi3+ ion is likely to prevent formation of a closed conformation (canonical structure of the holo-protein), resulting in a non-native metal coordination. It is suggested that transferrin retains the open conformation (characteristic of the apo-form) upon binding Bi3+, with only two ligands in the metal coordination sphere provided by the protein itself. This suggestion is corroborated by the results of circular dichroism measurements in the near-UV range. Since the cellular consumption of metals in the transferrin cycle critically depends upon recognition of the holo-protein complex by the transferrin receptor, the noncanonical conformation of the transferrin-bismuth complex may explain very inefficient delivery of bismuth to cells even when a high dosage of bismuth-containing drugs is administered for prolonged periods of time.

NMR spectroscopy of Group 13 metal ions: biologically relevant aspects

In spite of the fact that Group 13 metal ions (Al(3+), Ga(3+), In(3+) and Tl(+/3+)) show no main biological role, they are NMR-active nuclides which can be used in magnetic resonance spectroscopy of biologically relevant systems. The fact that these metal ions are quadrupolar (with the exception of thallium) means that they are particularly sensitive to ligand type and coordination geometry. The line width of the NMR signals of their complexes shows a strong dependence on the symmetry of coordination, which constitutes an effective tool in the elucidation of structures. Here we report published NMR studies of this family of elements, applied to systems of biological importance. Special emphasis is given to binding studies of these cations to biological molecules, such as proteins, and to chelating agents of radiopharmaceutical interest. The possibility of in vivo NMR studies is also stressed, with extension to (27)Al-based MRI (magnetic resonance imaging) experiments.

The Entering of Indium-111 and Iron-59 into the Hepatocytes from Partially Hepatectomized Rats Differ from That of Gallium-67

We recently suggested that the transferrin (Tf)-gallium-67 (67Ga) complex dissociated on the surface of the hepatocytes after partial hepatectomy and free 67Ga bound to heparan sulfate in the extracellular matrix. In the present study, we investigated whether the entering of indium-111 (111In) and iron-59 (59Fe) with high affinity to transferrin differed from the entering of 67Ga by the hepatocytes after partial hepatectomy. 111In was almost taken by the plasma and little taken by the red blood cell. On the other hand, the uptake of 59Fe by the red blood cell was higher than plasma. The uptake of 59Fe by the bone marrow was significantly higher than that of 111In. The uptake of 111In and 59Fe by the liver tissue was reached a maximum 2 d after partial hepatectomy but the uptake ratio of 111In was lower than that of 59Fe. We suspected that the uptake of 59Fe by the liver tissue was the highest because of the high binding affinity of Tf-59Fe to Tf-receptor. The entering of 111In and 59Fe into the hepatocytes was also reached a maximum 2 d after partial hepatectomy but the ratio of 59Fe was slightly lower than that of 111In. These results suggested that the binding affinity to Tf could have played a crucial role in the differences of the entering of 111In, 59Fe and 67Ga into the hepatocytes of partially hepatectomized rats.

Intrathecal cytotoxic T-cell immunotherapy for metastatic leptomeningeal melanoma

A 49-year-old patient with primary, recurrent melanoma on the lower extremity developed metastatic leptomeningeal melanoma that did not respond to treatment with radiation therapy or intrathecal interleukin 2 (IL-2). Disease was characterized by neurological symptoms, including loss of hearing, loss of short-term memory, and gait disturbance. CD8+ CTLs were generated in vitro using autologous dendritic cells pulsed with peptides from the melanoma-associated antigens tyrosinase (145-156), Melan-A/MART-1 (26-35), and gp100/Pmel 17 (209-217). The CTLs exhibited up to 74% specific lysis against peptide-pulsed autologous EBV-transformed B cells, with Melan-A-specific CTLs yielding the greatest lytic activity. CD8+ CTLs possessed a type 1 cytokine profile, expressing tumor necrosis factor alpha and IFNgamma but not IL-4. Infusions of CTLs were supported with systemic low-dose IL-2 administration. 111In labeling and computerized gamma imaging were used to monitor the distribution of CTLs up to 48 h after infusion. Intra-arterial delivery via the right carotid artery was followed by redistribution of the CTLs to the lungs, liver, and spleen within 16 h. In contrast, delivery via an indwelling Ommaya reservoir resulted in prolonged retention of CTLs within the brain for at least 48 h after infusion. Marked but transient elevations in tumor necrosis factor alpha, IFN-gamma, and IL-6 in the cerebrospinal fluid were observed within 4 h of CTL infusion. There was no evidence of tumor progression throughout the treatment period, and clinically the patient showed some resolution of neurological symptoms.

Stereoselective synthesis of C5-C20 and C21-C34 subunits of the core structure of the aplyronines. Applications of enantioselective additions of chiral allenylindium reagents to chiral aldehydes

The stereoselective synthesis of a C5-C20 and a C21-C34 subunit of the aplyronine family of polyketide marine macrolides has been achieved. These subunits contain all 15 stereocenters of the core structure. Six of the 15 stereocenters were introduced through enantioselective and diastereoselective additions of chiral allenylindium reagents to alpha-methyl-beta-oxygenated propionaldehydes. The products of these additions were further transformed by reactions involving the terminal alkynyl substituent produced in the addition reactions. Unlike previous applications of this methodology, the present synthesis employs Pd(0)-catalyzed transmetalations of chiral allenylpalladium intermediates to generate the chiral allenylindium reagents in situ.

The role of fibronectin in platelet adhesion to plasma preadsorbed polystyrene

Platelet adhesion to synthetic surfaces that come in contact with blood is mediated by the adsorption of adhesive plasma proteins, especially fibrinogen. However, the roles of other adhesive proteins, such as fibronectin, vitronectin, and von Willebrand factor in platelet adhesion are not yet clear. In this study, the role of fibronectin in platelet adhesion to surfaces was assessed using three approaches. First, platelet adhesion was measured on Immulon I preadsorbed with fibronectin-depleted plasma or fibronectin-depleted plasma replenished with increasing amount of fibronectin. Under these conditions, fibronectin adsorbed from plasma did not have any effect on platelet adhesion, while fibrinogen played a major role in mediating platelet adhesion. Since fibronectin might play a role in platelet adhesion to surfaces which adsorb little or no fibrinogen, we also used two other strategies to assess the potential role of fibronectin. One was to use platelets treated with a platelet activation inhibitor, prostaglandin E1, which prevents the activation of platelet fibrinogen receptor GP IIb/IIIa. The adhesion of prostaglandin E1-treated platelets to Immulon I preadsorbed with plasma was greatly decreased compared to that of untreated platelets, but was increased by the addition of supernormal concentrations of fibronectin to the plasma. This suggests that GP Ic/IIa, rather than GP IIb/IIIa, might be the platelet receptor which is responsible for platelet adhesion to surface-bound fibronectin. Finally, we studied the effect of fibronectin on platelet adhesion to surfaces preadsorbed with fibronectin-depleted afibrinogenemic plasma. We found that fibronectin re-addition to fibronectin-depleted afibrinogenemic plasma increased platelet adhesion. However, our most important finding was that fibronectin seems to play little or no role in mediating platelet adhesion to polystyrene surfaces preadsorbed with normal plasma.

Comparative pulmonary absorption, distribution, and toxicity of copper gallium diselenide, copper indium diselenide, and cadmium telluride in Sprague-Dawley rats

Copper gallium diselenide (CGS), copper indium diselenide (CIS), and cadmium telluride (CdTe) are novel compounds used in the photovoltaic and semiconductor industries. This study was conducted to characterize the relative toxicities of these compounds and to evaluate the pulmonary absorption and distribution after intratracheal instillation. Female Sprague-Dawley rats were administered a single equimolar dose (70 mM) of CGS (21 mg/kg), CIS (24 mg/kg), CdTe (17 mg/kg), or saline by intratracheal instillation. Bronchoalveolar lavage fluid (BALF) protein, fibronectin, inflammatory cells, lung hydroxyproline, and tissue distribution were measured 1, 3, 7, 14, and 28 days after instillation. Relative lung weights were significantly increased in CIS- and CdTe-treated rats at most time points. Inflammatory lesions in the lungs consisting of an influx of macrophages, lymphocytes, and PMNs were most severe in CdTe-treated rats, intermediate in CIS-treated rats, and minimal in rats receiving CGS. Hyperplasia of alveolar type 2 cells was present in CIS- and CdTe-treated rats and was greatest in CdTe-treated rats. Pulmonary interstitial fibrosis was observed in CdTe-treated rats at all time points. All three compounds caused marked increases in total BALF cell numbers, with the greatest increase observed in CIS-treated rats. BALF protein, fibronectin, and lung hydroxyproline were significantly increased in all treated animals and were highest in CdTe-treated animals. There was no apparent pulmonary absorption or tissue distribution of CGS. Indium levels increased in extrapulmonary tissues of CIS-treated rats, although Cu and Se levels remained unchanged. CdTe was absorbed from the lung to a greater extent than CGS and CIS. Cd and Te levels decreased in the lung and increased in extrapulmonary tissues. Of these compounds CdTe presents the greatest potential health risk because it causes severe pulmonary inflammation and fibrosis and because it is readily absorbed from the lung may potentially cause extrapulmonary toxicity.

New hydroxybenzyl and hydroxypyridylmethyl substituted triazacyclononane ligands for use with gallium(III) and indium(III)

The 67Ga(III) and/or 111In(III) complexes of four new hexadentate ligands have been prepared and evaluated in vitro and in vivo. These substituted triazacyclononane ligands bind the metal ion through three tertiary ring nitrogens and three oxygens from pendant phenolic or hydroxypyridyl arms. The hydroxypyridyl moieties increase the aqueous solubility of the metal complexes while retaining a lipophilic character. As indicated by their large positive partition coefficients, the phenolic ligands proved to be significantly more lipophilic than the hydroxypyridyl ligands. Biodistribution in Sprague-Dawley rats indicated that the more lipophilic phenolic complexes cleared the body primarily through the liver, while the less lipophilic hydroxypyridyl complexes cleared rapidly, primarily through the kidney. To differentiate the clearance characteristics of these radiolabeled compounds, radiochemical purity of selected complexes in vivo was measured. The complexes were evaluated for overall charge in vitro and in vivo, in plasma samples. In addition, plasma and urine were analyzed for possible metabolites. With one exception, each complex was unmetabolized in vivo. All complexes and metabolites formed were neutral in vitro and in vivo. Extended stability in serum of selected radiometal complexes has been measured. Each complex measured was stable to exchange with transferrin, up to 72 h, as expected from the large stability constants of the complexes. The clearance characteristics of the hydroxypyridyl and phenolic ligands, however, were markedly different. The rapid hepatic clearance of the phenolic ligands indicates potential as bifunctional chelates for Ga(III) or In(III).

Tissue distribution and elimination of indium in male Fischer 344 rats following oral and intratracheal administration of indium phosphide

The use of indium phosphide (InP) in the semiconductor industry has raised concerns about potential occupational exposure. The tissue distribution and elimination of indium were investigated in adult male Fischer 344 rats following either a single or 14 consecutive daily oral doses, or following an intratracheal instillation of InP (10 mg/kg). The concentrations of indium ions in blood, urine, feces, and tissues were quantified either using direct acid digestion followed by electrothermal atomic absorption spectrophotometry (ET-AAS) or using an extraction method with methyltricapryl ammonium ions to remove indium from the matrix followed by ET-AAS. Indium was poorly absorbed from the gastrointestinal tract in both single and multiple oral dose studies. Upon its absorption, indium was relatively evenly distributed among the major organs such as liver, kidney, lung, spleen, and testes. By 96 h after oral dose treatment, less than 0.11% of the dose of indium was recovered from tissues in the single- or multiple-dose experiment. At 96 h, retention of indium in the body was about 0.36% of the dose (except for lung) following intratracheal instillation of InP. Following oral dose administration, the majority of indium was recovered from the gastrointestinal tract and its contents. The high recovery of indium (73% of the dose) in the feces after intratracheal instillation presumably reflects mucociliary clearance and/or biliary excretion of indium. Urinary indium accounted only for 0.08-0.23% of the dose during a 240-h collection period in both single- and multiple-dose studies. It seems that fecal excretion serves as the major route for indium elimination, and this results from poor absorption. Because of the poor absorption of indium following multiple oral doses or intratracheal instillation of InP, it seems unlikely that indium will accumulate in the body following InP exposure.

How the anti-(metal chelate) antibody CHA255 is specific for the metal ion of its antigen: X-ray structures for two Fab'/hapten complexes with different metals in the chelate

Antibodies with bound metal-chelate haptens provide new means for exploiting the diverse properties of metallic elements. The murine monoclonal antibody CHA255 (IgG1 lambda) binds the metal-chelate hapten indium (III)-4-[N'-(2-hydroxyethyl)thioureido]-L-benzyl-EDTA (designated In-EOTUBE) with high affinity (K(a) = 1.1 x 10(10) M-1). Antibody binding is highly specific for the indium chelate; the affinity decreases as much as 10(4) with other metals, even those having ionic radii close to indium. To better understand this selectivity, the crystal structure of the antigen-binding fragment (Fab') of CHA255 complexed with its hapten, In(III)-EOTUBE, was determined by molecular replacement and refined at 2.2-A resolution. The structure of CHA255 Fab' complexed with Fe(III)-EOTUBE was also determined and refined at 2.8-A resolution. In both structures, the hapten's EDTA moiety is half-buried near the center of the complementarity-determining regions (CDR's). Five of the six CDR's on the Fab' interact with the hapten through protein side-chain atoms (but not main-chain atoms). A novel feature of the In-EOTUBE/Fab' complex is coordination of the indium by N epsilon of one histidine from the heavy chain's third CDR (distance = 2.4 A). The histidine coordination is not observed in the Fe-EOTUBE/Fab' complex, due mainly to a slightly different hapten conformation that reduces metal accessibility; this may partially explain the 20-fold lower affinity of CHA255 for iron hapten. An unexpected feature of the Fab' overall is an elbow angle of 193 degrees (the angle between the pseudodyad axes of the Fab's constant and variable domains).

Metabolism of subcutaneous administered indium arsenide in the hamster

Indium arsenide (InAs) is partially dissociated in vivo to form inorganic arsenic and indium and excreted into the urine and feces. InAs dissolves slowly over time with deposits at the site of injection. Results of this study demonstrated that the principal metabolite of arsenic in the urine of hamsters was dimethylated arsenic (DMA). Inorganic arsenic and DMA accumulated in the fur, but the concentrations of indium were very low in this matrix. Urine and feces were the principal routes of elimination from the body. Analysis of tissues for arsenic demonstrated as concentrations in the parts per billion range. Results of these studies indicate that InAs is dissociated in vivo with release of both the indium and arsenic moieties to target tissues.

Induction of feline immunodeficiency virus-specific cytolytic T-cell responses from experimentally infected cats

We have examined the in vitro induction and activity of feline immunodeficiency virus (FIV)-specific cytolytic T cells obtained from cats experimentally infected for 7 to 17 weeks or 20 to 22 months with the Petaluma isolate of FIV. Normal or FIV-infected autologous and allogeneic T lymphoblastoid cells were used as target cells in chromium-51 or indium-111 release assays. When effector cells consisted of either fresh peripheral blood mononuclear cells or concanavalin A- and interleukin-2-stimulated cells, only low levels of cytotoxicity were observed. However, the levels of FIV-specific cytotoxicity were consistently higher in both groups of cats following in vitro stimulation of the effector cells with irradiated, FIV-infected autologous T lymphoblastoid cells and interleukin-2. The effector cells lysed autologous but not allogeneic FIV-infected target cells and were composed predominantly of CD8+ T cells, indicating that the FIV-specific cytotoxicity measured in this system is mediated by CD8+, major histocompatibility complex class I-restricted T cells. These studies show that FIV-specific cytolytic T cells can be detected as early as 7 to 9 weeks postinfection, and they define a system to identify virus-encoded epitopes important in the induction of protective immunity against lentiviruses.

Distribution of111 in-bleomycin complex in small cell lung cancer cells by autoradiography

The distribution of 111In-bleomycin Complex (111In-BLMC) in small cell lung cancer (SCLC) cells was studied by autoradiography. SCLC cells were exposed to 111In-BLMC and 111Indium chloride (111InCl3) for 1 hour, 3 hours, and 4 hours; washed with fresh medium; and spread on slides. The slides were smeared with NTB2 (NTB3) emulsion by wet or dry-mount technique and exposed 3 to 15 days. 111In-BLMC was found to localize in the cell nucleus and nuclear membrane (78.3%); 111InCl3 located mainly in the cytoplasm (52.3%). This distribution of labeled BLM may explain the mechanism of killing SCLC cells by 111In-BLMC.

Kinetics of the dissociation of indium-(p-substituted-benzyl)ethylenediaminetetraacetic acid hapten analogues from the monoclonal anti-hapten antibody CHA255

Half-lives were measured for the dissociation of a series of 20 indium-benzyl-EDTA derivatives from a monoclonal antibody that binds to them. Most haptens gave expected monoexponential dissociation curves with half-lives ranging from approximately 8 to approximately 100 min at 22 +/- 1 degree C. Precise (+/- approximately 2.5%) determinations were made using centrifugal ultrafiltration to separate free from bound hapten. A strong pH dependence of the dissociation half-life was found for the two haptens studied. Activation enthalpies were identical (23 +/- 1 kcal/mol) for the dissociation of four haptens, suggesting that, in contrast to individual rate constants, this parameter is insensitive to hapten modification. The dissociation half-lives provided evidence for the location of a positive charge in the binding site, but gave no clear indication of the role of hydrophobic interactions or of steric requirements in hapten binding. While variations in ionic strength had no effect on the dissociation rate, lowering surface tension with dioxane increased the rate somewhat. Three hapten-antibody complexes showed biexponential dissociation rates. It is postulated that this results from distinct conformations of the complex dissociating at different rates. The dissociation rate constant was found to be an extremely sensitive indicator of the hapten-antibody interaction that can be measured very precisely.

Development and characterization of monoclonal antibodies with specificity for metallic radioisotope chelators linked to antibodies and other proteins

Monoclonal antibodies with specificity for the diethylenetriaminepentaacetic acid (DTPA) portion of the GYK-DTPA (glycyl-tyrosyl-lysine-DTPA) linker structure used to chelate metals to immunoglobulins have been prepared. A significant proportion of these antibodies were lambda light chain isotype. Competition assays demonstrated that DTPA, rather than GYK, was the binding site of the antibodies tested. These monoclonal antibodies should be useful reagents for use in assays specific for the presence of the common linker structure used to chelate metallic radioisotopes to monoclonal antibodies. The antibodies tested did not discriminate between chelated and unchelated DTPA.

Effect of ABO incompatibility on the fate in vivo of 111Indium granulocytes

The effect of ABO incompatibility on the in vivo fate of 111Indium granulocytes was determined. The intravascular recovery and survival (t1/2) and extravascular migration into a skin window of normal-donor granulocytes did not differ in 15 subjects from the values obtained in four controls who received ABO-compatible granulocytes. Nor was the correlation between the ABO antibody titers and the in vivo measurements strongly positive. It is concluded that ABO incompatibility did not alter the in vivo fate of granulocytes.

Comparison of gallium-67 versus indium-111 monoclonal antibody (96.5, ZME-018) in detection of human melanoma in athymic mice

We compared the biodistribution of two radiolabeled, whole, tumor selective monoclonal antibodies [( 111In]96.5, [111In]ZME-018) to 67Ga in nude mice bearing a human melanoma known to express p97 antigen. Localization of gallium was determined 48 hr following i.v. injection. Localization of the radiolabeled antibodies was determined at 3 days and 7 days following i.v. injection. All agents showed more or less similar absolute tumor uptake which varied between 22% and 36% of the injected dose per gram of tumor. Only the tumor uptake of [111In]96.5 antibody at 7 days was significantly lower than the 67Ga uptake at 48 hr. However, uptake in normal tissues was generally higher for both antibodies at 3 and 7 days than for 67Ga uptake at 48 hr. Therefore, the tumor-to-blood ratio for 67Ga was tenfold higher than that for either antibody, the tumor-to-muscle ratio was twofold higher. Bone was the only organ in which the tumor-to-organ ratio was consistently higher with radiolabeled antibody than with 67Ga. The tumor-to-liver and tumor-to-intestine ratios were comparable. Localization of the two tumor selective antibodies was greater than a nonspecific "control antibody" [( 111In]CEA) and change in specific activity from 0.17 mCi/mg to 3.3 mCi/mg did not influence localization. From these animal data it may be anticipated that tumor imaging with [111In]96.5 or [111In]ZME-018 will not be superior to imaging with 67Ga for detection of melanoma.

Kinetic model for the biodistribution of an 111In-labeled monoclonal antibody in humans

Using data from 12 patients, we have analyzed the pharmacokinetics of 111In-9.2.27, an antimelanoma monoclonal antibody, following i.v. infusion. Plasma data and scintillation camera images obtained from patients receiving either 1, 50, or 100 mg of monoclonal antibody indicated dose-dependent (i.e., saturable) kinetics. Based on these observations and known immunoglobulin kinetics, we developed a nonlinear compartmental model to describe the biodistribution of 111In-9.2.27 and the other coinjected 111In-associated compounds. The model included (a) three compartments representing intact 111In-9.2.27 ("plasma," "nonsaturable," and "saturable binding" compartments), (b) four compartments representing 111In-diethylenetriaminepentaacetic acid, and (c) one compartment representing 111In in an undetermined chemical form ("extravascular delay" compartment). Analysis of the rate of urinary excretion relative to plasma concentration indicated that the saturable binding compartment was a site for catabolism of monoclonal antibody. Further examination of the urinary data, together with previous studies of the site(s) of immunoglobulin catabolism, suggested that additional elimination took place from either the plasma or the nonsaturable compartment. The model indicated that to fill the saturable sites would require a dose of approximately 0.5 mg and suggested that greater than 3.5 mg would maintain saturation for 200 h. Computer integration of gamma camera counts over the spleen revealed a clear saturable component of uptake, whereas integration over the liver showed no such pattern. The proposed model was fitted to the liver and spleen imaging data by summing fractions of model simulations of each compartment. That analysis confirmed the suspected saturable uptake by the spleen (21% of the saturable binding compartment) and revealed a quantitatively important component of saturation in the liver (35% of the saturable binding compartment) that was not obvious from initial examination of the images. When the results were expressed on a concentration basis, the spleen accounted for 247% of the saturable compartment per kg, whereas the liver accounted for 25%/kg. The bone marrow also showed saturable uptake; hence, the saturable uptake may relate to the sinusoidal blood supply characteristic of liver, spleen, and marrow. The model predicts the dose levels required to overcome saturable background, suggests appropriate doses and schedules for cold loading strategies, and provides a format for explicit inclusion of tumor antigen.

Cation permeability of the blood-brain barrier in streptozotocin-diabetic rats

Decreased sodium permeability across the blood-brain barrier occurs in streptozotocin-treated rats after 2 weeks of diabetes. To establish whether this is a phenomenon specific for cations, the blood-brain barrier permeability for sodium, potassium and calcium was studied with an arterial integral uptake technique. Experiments were performed in control rats and, after two weeks after diabetes induction, in untreated streptozotocin-diabetic rats and in insulin-treated streptozotocin rats. In untreated diabetes, the neocortical blood-brain barrier permeability for sodium decreased by 35% (5.2 +/- 1.7 vs 3.4 +/- 1.1 10(-5).cm3.s-1.g-1) and potassium permeability by 39% (19.8 +/- 5.7 vs 12.1 +/- 3.9 10(-5).cm3.s-1.g-1), whereas no differences in calcium permeability occurred. Insulin treatment was associated with an increase in the blood-brain barrier permeability to sodium (4.8 +/- 1.0 10(-5).cm3.s-1.g-1) as compared to untreated diabetes (3.4 +/- 1.1 10(-5).cm3.s-1.g-1). It is concluded that the observed changes in sodium and potassium permeability cannot be caused by electrostatic membrane changes. More specific abnormalities of the transport of sodium and potassium across the blood-brain barrier are likely to occur; disturbances in the sodium-potassium-pump activity could account for such alterations.

Pharmacological actions of WEB 2086, a new specific antagonist of platelet activating factor

WEB 2086, a thieno-triazolodiazepine, is a potent and specific antagonist of platelet activating factor (PAF) in vitro and in vivo. This compound inhibits PAF-induced human platelet and neutrophil aggregation in vitro (IC50 = 0.17 and 0.36 microM, respectively) but has little or no effect on the action of other platelet aggregating agents. In comparison with kadsurenone, ketotifen or thiazinamium chloride, WEB 2086 was 26 to 200 times more potent in the PAF-induced platelet aggregation. In anesthetized guinea pigs, pretreatment with 0.1 to 2.0 mg/kg p.o. or 0.01 to 0.5 mg/kg i.v. of WEB 2086 inhibits dose-dependently the accumulation and aggregation of 111Indium labeled platelets, bronchoconstriction, systemic hypotension and also the lethal effect due to an i.v. PAF infusion [30 ng/(kg X min)] or intratracheal instillation of PAF (300 micrograms/kg). Under the same experimental conditions in guinea pigs, WEB 2086 given by inhalation achieved a similar anti-PAF activity. In anesthetized rats, the hypotension induced by an i.v. PAF infusion was also reversed (ED50 = 0.052 mg/kg i.v.). The increase in cutaneous vascular permeability due to intradermal PAF (25 ng/site) was inhibited dose-dependently by WEB 2086 (0.025-2 micrograms/site) in rats. Because of its structural relationship to triazolodiazepines, WEB 2086 was examined for anticonvulsant and sedative action. Up to doses of 300 and 800 mg/kg p.o., respectively, no effects were found. In conclusion, WEB 2086 is a potent and specific PAF antagonist with triazolodiazepine structure but without sedative activity.

Binding properties of 111In-diethylenetriaminepentaacetic acid (DTPA)-fragment E1,2, a fibrin-specific probe, are dependent on use of protecting complex during attachment of DTPA groups

Fragments E1 and E2, plasmic degradation products of crosslinked fibrin, bind specifically to polymers of fibrin. A mixture of these fragments, denoted as fragment E1,2, was radiolabeled with 111In after covalently attaching metal chelating groups (diethylenetriaminepentaacetic acid, DTPA) to the fragment, using two approaches. In the first approach, DTPA groups were attached directly to purified fragment E1,2. In the second approach, attachment sites of DTPA groups were directed away from the active region of the molecule by having fragment E1,2 bound in complex, with its active sites protected during the derivatization. Direct attachment of DTPA groups to fragment E1,2 resulted in complete loss of binding to fibrin in vitro. When derivatized in complex, 111In-DTPA-fragment E1,2 retained a higher degree of binding to human fragment DD and human plasma clots in vitro than did radioiodinated fragment E1, even when up to eight DTPA groups were attached per molecule of fragment E1,2.

Indium-111-labeled autologous leukocyte imaging and fecal excretion. Comparison with conventional methods of assessment of inflammatory bowel disease

This study was designed to evaluate the role of 111In-labeled leukocyte imaging and fecal excretion in the assessment of inflammatory bowel disease. We compared these tests to various indices of disease activity in Crohn's disease, to Truelove's grading in ulcerative colitis, and to endoscopy, x-ray, and pathology in both diseases. Eleven controls, 16 patients with Crohn's disease, 13 with ulcerative colitis, and 3 with other types of acute bowel inflammation were studied (positive controls). Indium scanning was performed at 1, 4, and 24 hr. Fourteen of 16 patients with active Crohn's disease had positive scans but in only five was localization accurate. One patient had inactive ulcerative colitis, and the scan was negative. Of 12 patients with active ulcerative colitis, 10 had positive scans but disease localization was accurate in only four. Disease extent was correctly defined in 1 of the 3 Positive Controls. There was no significant difference in the accuracy of scanning at 1, 4, or 24 hr. 111In fecal excretion was significantly higher in patients with inflammatory bowel disease than in controls, and there was correlation between 111In fecal excretion and most of the indices of disease activity in Crohn's disease. In ulcerative colitis, 111In fecal excretion did not correlate with Truelove's grading but reflected colonoscopic assessment of severity. In conclusion, 111In-labeled leukocyte scanning lacks sensitivity with respect to disease extent, but fecal excretion of 111In correlates well with disease severity as determined by other methods.

Localization of human osteogenic sarcoma xenografts in nude mice by a monoclonal antibody labeled with radioiodine and indium-111

Monoclonal antibody OST7 reacts specifically with human osteogenic sarcoma. Whole immunoglobulin G (IgG) and the F(ab')2 fragment of OST7 were labeled with radioiodine and indium-111 (111I), and injected into athymic nude mice bearing xenografts of human osteogenic sarcoma (KT005). All radiolabels retained their antigen-binding activities allowing clear visualization of transplanted tumors. Tissue distribution, however, varied. The net tumor concentration of 111In-lableled whole IgG was higher and was retained longer than that of radioiodinated one, but 111In-labeled antibody showed a lower tumor-to-liver and tumor-to-kidney ratio. In radioiodinated OST7, F(ab')2 fragments provided much better images with much higher tumor-to-tissue ratios than whole IgG. Using F(ab')2 fragments as a carrier for 111In, little image improvement was obtained due to the high radioactivity in the liver and kidney. The different distributions among these radiolabels suggest that the choice between intact igG and F(ab')2 fragments and between radioiodine and 111In depends on the intended use.

Indium-111 T101 monoclonal antibody is superior to iodine-131 T101 in imaging of cutaneous T-cell lymphoma

We have reported that [111In]T101 is highly effective in the detection of cutaneous T-cell lymphoma (CTCL) in nodal and cutaneous (erythroderma and tumor) sites. This study compares the biodistribution of [131I]T101 (1 to 7.1 mg, 2 mCi) in four patients with CTCL; two of these patients also received [111In]T101 (1 mg, 5 mCi). There was rapid clearance of [131I]T101 from whole-body, spleen, liver, and bone marrow, with evidence of loss of 131I tracer from the T101. Lymph node uptake was minimal in three of four patients, and there was no localization in skin lesions. This contrasted with [111In]T101 where there was prolonged retention of activity in these organs and excellent uptake in skin tumors, erythroderma, and lymph nodes. The study showed that [131I]T101 was suboptimal for imaging CTCL patients and demonstrates that the isotope or labeling method can dramatically alter the apparent biodistribution and tumor targeting of a given monoclonal antibody.

Pharmacokinetics of the monoclonal antibody B72.3 and its fragments labeled with either 125I or 111In

A comparison of the pharmacokinetics of intact B72.3 (a murine monoclonal antibody specific for human breast and colon carcinoma) with F(ab')2 and Fab fragments labeled with 111In and 125I was done in athymic mice bearing target (LS174T) and non-target (HCT-15) tumors. IgG B72.3 labeled with either isotype imaged LS174T. Biodistributions of both labels were similar in all organs except liver. F(ab')2 also imaged the LS174T tumor, while Fab bearing either isotype did not. The blood clearance was Fab greater than F(ab')2 greater than immunoglobulin G B72.3 for both isotopes. 111In-labeled fragments yielded large accumulations in the kidneys which persisted for 2 days. The different patterns of biodistribution for the various forms of B72.3 labeled with the two isotopes suggest that the most desirable combination of fragment and isotope will depend on the intended use.

On the theory of the measurement of the first-pass pulmonary extraction using the indicator dilution technique

Theory and concept of extraction involving invasive as well as non-invasive procedures to assess the first-pass extraction of tracers based on the indicator dilution technique are discussed. The experimental result of a non-invasive method using a gamma scintillation camera-computer system of first-pass pulmonary extraction of N-Isopropyl-123I-p-Iodoamphetamine (123I-IMP) are also discussed.

[Methodological aspects of bone marrow research using 111In-citrin]

A study of 111In-citrin distribution and kinetics in the body of patients without hemopoietic disorder showed the accumulation (up to 20%) of the injected drug in the bone marrow. Organ fixation, elimination and other pharmacokinetic indices confirming 111In-citrin functional applicability for investigation of the red bone marrow were determined shortly after intravenous injection and in 24 h using a total body meter. These data formed the basis for the calculation of radiation exposures and the solution of methodological problems related to a radionuclide study of the bone marrow in cancer and leukemic patients. 111In concentration in the pelvic bones determined with the help of the total body meter, reflected the total red bone marrow functional activity and was in reverse correlation with a RP elimination value. Total body scintigraphy 24 h after the drug administration made it possible to visualize the bone marrow distribution in the body and to reveal signs of general or local disorders of bone marrow functional activity in leukemias or malignant tumors after combination therapy.

Some applications of the indium-113m-transferrin technique for gamma-radiation detection of microvascular effects of serotonin and ischemia

The distribution of systematically injected In-113m (t1/2 = 100 min) in organs of the rat was analyzed, and the use of the isotope for in vivo and in vitro gamma-radiation detection studies of blood plasma protein extravasation was demonstrated in skin, muscle, and tumor. In-113m was slowly excreted from rats. One to 6 h after injection the blood held 3% and 2%, respectively, of injected radioactivity/g tissue wet weight; skin and muscle held 0.1%-0.2%/g; liver, colon, and spleen held approximately 1%/g; lungs 1.5%-1.3%/g and kidneys 2.8%-3.3%/g. Scintillation camera technique revealed 40%-80% extraaccumulation of In-113m in a control extremity upon local administration of serotonin and 20%-40% in an extremity with a transplanted tumor, thus indicating a lower effect of serotonin in tumor microvascular circulation than in muscle and skin. In vitro detection of In-113m radiation by a well-counter in dissected tissues showed no effects of serotonin in the tumor and a four- to five-fold increase of radioactivity in muscle and skin, thus confirming blood protein extravasation upon serotonin treatment in these tissues. External analyses of In-113m in the vascular system using one miniaturized probe directed toward an area of interest showed that the method was too sensitive to movements of the animal, and second probe directed toward a control area is needed.

Mechanism of ionophoric transport of indium-111 cations through a lipid bilayer membrane

The use of mobile ionophores to facilitate the transport of 111In through a lipid bilayer membrane has broad applications in liposome technology and cell labeling. However, the mechanism of such ionophore-mediated transport of 111In through a lipid bilayer membrane is not completely clear. The present report describes the correlations of the behaviors of ionophoric loading of 111In into liposomes with the lipophilicity and the indium-binding affinity of three ionophores, namely, 8-hydroxyquinoline, acetylacetone, and tropolone. Our results suggest that the mechanism of the ionophoric transport of 111In through a lipid bilayer membrane involves the rapid exchange of 111In cations among the ionophores in both the aqueous solution and the lipid bilayer. Furthermore, the effectiveness of an ionophore in facilitating the transport of 111In from the external aqueous compartment to the entrapped nitrilotriacetic acid depends not only on the lipophilicity of the [111In]ionophore complex, but also on the lipophilicity of the free ionophore itself and the competition of 111In between nitrilotriacetic acid inside the inner aqueous compartment of the liposome and the ionophore imbedded in the lipid bilayer membrane of the liposome.

Metabolizable 111In chelate conjugated anti-idiotype monoclonal antibody for radioimmunodetection of lymphoma in mice

The relative biological properties of 111In-labeled monoclonal antibodies (MoAb) coupled with a conventional bifunctional chelate (BC) and a new, enzyme metabolizable, bifunctional chelate (BCM) were investigated. A rat IgG2a MoAb against idiotype from a mouse B-cell lymphoma was utilized. Mice bearing B-cell lymphomas in the subcutaneous tissues of the flank were given IV-injections of labeled MoAb and imaged or killed for organ counting at 24 h or 48 h. Rat anti-dinitrophenyl IgG2a MoAb and non-specific polyclonal mouse IgG were used as controls. Compared to BC, the use of BCM resulted in a substantial decrease in blood background activity, a shorter biological half-life and an increase in tumor to blood ratio at the expense of a moderate decrease in absolute tumor uptake. The versatile chemistry of these C-1 substituted bifunctional chelates provides a variety of possible enzyme cleavable moieties for further investigation.

Accumulation of indium-111-labeled neutrophils and gallium-67 citrate in rabbit abscesses

A rabbit abscess model was developed to study the effect of abscess age on the accumulation of indium-111-labeled neutrophils ([111In]N) versus gallium-67 citrate (67Ga). Abscesses 1-2 hr, 6-8 hr, 24 hr, and 7 days old were induced by subcutaneous injection of autoclaved colon contents prior to i.v. administration of either [111In]N or 67Ga. Radioactivity in the abscesses was determined 48 hr postinjection. Accumulation of [111In]N was inversely proportional to abscess age. Seven-day-old abscesses were inconsistently seen on [111In]N scans. In contrast, 67Ga accumulation was not affected by abscess age and all abscesses could be identified on a scan 48 hr postinjection. Scans with [111In]N were clearly superior to 67Ga scans for demonstrating early abscesses. Since 67Ga accumulated to a greater extent than [111In]N in abscesses 7 days old, it may be a superior imaging agent for older abscesses.

Metal decomposition rates of 111In-DTPA and EDTA conjugates of monoclonal antibodies in vivo

We have studied the metal chelate decomposition rates in vivo in both 111In-labelled benzyl EDTA and DTPA (bicyclic anhydride) conjugates of monoclonal anti-IAk IgG2a with identical Ka = 1 X 10(11)M-1 in both Ag+ve and Ag-ve mice. Twenty mu Ci was given i.v. and whole body counting done immediately and daily for 10 days, with six to eight mice in each group. Half the mice in each group received i.p. injections of 5.0 mg CaNa2 EDTA chase (Versenate) to facilitate urinary excretion of free 111In. 50% of control 111In-citrate remained at nine days but only 8% with chase. No significant loss of 111In with chase occurred with C1 substituted EDTA conjugates. A 19% increase in excretion was demonstrated with the chase in mice given DTPA conjugates (1.9% per day). While this will not interfere with radioimmunoimaging up to 24 h after injection, waiting periods of a week or longer will produce significant background of free 111In in the reticuloendothelial system, RES. 111In-EDTA stability was important in accurate metabolic rate measurements of anti-IAk; T1/2 = 7.0 days in Ag-ve mice, T1/2 = 9.3 days in Ag-ve mice. It will be important to measure the in vivo rates for each new metal complex, especially those intended for therapy such as Y-90.

The carriage and delivery of substances to lymphatic tissues by recirculating lymphocytes. II. Long-term selective irradiation of the spleen and lymph nodes by deposition of indium-114m

Recirculating lymphocytes were used to carry an isotope of indium, In-114m. The isotope has a half-life of 50 days, and emits both gamma and beta particles, properties that may be useful clinically. In-114m-labelled rat thoracic duct lymphocytes (TDL), injected intravenously, migrated to traffic areas in spleen and lymph nodes. The radioactivity was transferred selectively to a resident, radioresistant phagocytic population located within the marginal zone and red pulp of spleen, where it remained for at least 6 weeks. That the isotope was relatively concentrated in traffic areas, but not elsewhere, suggested that In-114m-TDL could be used as a means of producing total lymphoid irradiation without damaging bone marrow. Recipients of In-114m-TDL developed a profound lymphocytopenia within 2-3 weeks of injection but gained weight at a comparable rate to control rats. The effect of In-114m-TDL injection was also examined in rats injected with a rapidly growing, malignant rat leukaemia. In-114m-TDL delayed the onset of the proliferative phase of the leukaemia from 10 days to 20 days in a dose-dependent fashion. Repeated weekly injections of In-114m-TDL prevented the onset of the leukaemia until the injections ceased after 11 weeks. The potential use of In-114m-labelled lymphocytes in diagnosis (by external imaging) or in treatment (by localized lymphoid irradiation) is considered.

[Experimental evaluation of the the possible use of 99mTc- and 133mIn-labelled aminomethylene phosphonates for skeletal scintigraphy]

The pharmacokinetics of 99mTc and 113mIn labeled aminopolymethyl phosphonic acids was studied in experiments on animals. Noticeable osteotropism of these compounds was shown. Scans of the rabbit and rat skeleton in health and experimental pathology 1 h after i.v. administration of these compounds were obtained making it possible to reveal the affected foci.

Metabolism and possible health effects of aluminum

Literature regarding the biochemistry of aluminum and eight similar ions is reviewed. Close and hitherto unknown similarities were found. A hypothetical model is presented for the metabolism, based on documented direct observations of Al3+ and analogies from other ions. Main characteristics are low intestinal absorption, rapid urinary excretion, and slow tissue uptake, mostly in skeleton and reticuloendothelial cells. Intracellular Al3+ is probably first confined in the lysosomes but then slowly accumulates in the cell nucleus and chromatin. Large, long-lived cells, e.g., neurons, may be the most liable to this accumulation. In heterochromatin, Al3+ levels can be found comparable to those used in leather tannage. It is proposed that an accumulation may take place at a subcellular level without any significant increase in the corresponding tissue concentration. The possible effects of this accumulation are discussed. As Al3+ is neurotoxic, the brain metabolism is most interesting. The normal and the lethally toxic brain levels of Al3+ are well documented and differ only by a factor of 3-10. The normal brain uptake of Al3+ is estimated from data on intestinal uptake of Al3+ and brain uptake of radionuclides of similar ions administered intravenously. The uptake is very slow, 1 mg in 36 years, and is consistent with an assumption that Al3+ taken up by the brain cannot be eliminated and is therefore accumulated. The possibility that Al3+ may cause or contribute to some specific diseases, most of them related to aging, is discussed with the proposed metabolic picture in mind.

Indium-111 labeled leukocyte uptake: false-positive results in noninfected pseudoaneurysms

Indium-111 (In-111) leukocyte scintigraphy was performed in two patients with postsurgical pseudoaneurysms as part of preoperative evaluation for evidence of graft infection. Despite positive In-111 uptake by the pseudoaneurysms, surgical and pathologic examinations failed to reveal any evidence of infection. The most likely explanation for the false-positive results is the labeling of "contaminating" platelets and erythrocytes in the leukocyte mixture. Caution must be exercised in interpretation of In-111 leukocyte scans in patients with postsurgical pseudoaneurysms.

Indium 111-mercaptopyridine N-oxide-labeled human leukocytes and platelets: mechanism of labeling and intracellular location of 111In and mercaptopyridine N-oxide

Human leukocytes and platelets were labeled in plasma with indium 111, by incubating cells first with 2-mercaptopyridine N-oxide (Merc) and then with ionic or weakly chelated 111In citrate. We investigated the mechanism by which this procedure enabled us to label cells in plasma. The interactions of 111In and Merc with cell membrane and cytoplasm were studied by homogenizing labeled cells and analyzing the homogenate by gel filtration. Studies were facilitated by use of sulfur 35-labeled Merc. Although 65% +/- 12.8% of added 111-In was incorporated in cells in presence of extracellular Merc, only 0.8% +/- 0.1% and 5.1% +/- 3.2% 35S-Merc was associated with 10(8) leukocytes and 10(10) platelets, respectively. In the absence of extracellular Merc, only 4.5% +/- 0.3% 111In was taken up by the cells. In each type of cell 83% to 99% of the cell-incorporated 35S Merc was associated with a cytoplasmic component with apparent molecular weight 5200 daltons, independently of the presence or absence of radioactive or stable indium. An approximately equal proportion of 111In was bound to similar cytoplasmic components in both types of cells. On adenosine diphosphate-induced platelet aggregation, less than 3% of platelet-bound 111In or 35S-Merc was released. These results indicate that it is the extracellular Merc that facilitates 111In labeling. It does not bind to cell membrane, but forms a lipid-soluble complex with 111In. This complex passively diffuses through the cell membrane, allows 111In to bind to cytoplasmic components, and provides a stable cell label.