Tumor Angiogenesis Phenotyping by Nanoparticle-facilitated Magnetic Resonance and Near-infrared Fluorescence Molecular Imaging

One of the challenges of tailored antiangiogenic therapy is the ability to adequately monitor the angiogenic activity of a malignancy in response to treatment. The α_vβ₃ integrin, highly overexpressed on newly formed tumor vessels, has been successfully used as a target for Arg-Gly-Asp (RGD)-functionalized nanoparticle contrast agents. In the present study, an RGD-functionalized nanocarrier was used to image ongoing angiogenesis in two different xenograft tumor models with varying intensities of angiogenesis (LS174T > EW7). To that end, iron oxide nanocrystals were included in the core of the nanoparticles to provide contrast for T₂*-weighted magnetic resonance imaging (MRI), whereas the fluorophore Cy7 was attached to the surface to enable near-infrared fluorescence (NIRF) imaging. The mouse tumor models were used to test the potential of the nanoparticle probe in combination with dual modality imaging for in vivo detection of tumor angiogenesis. Pre-contrast and post-contrast images (4 hours) were acquired at a 9.4-T MRI system and revealed significant differences in the nanoparticle accumulation patterns between the two tumor models. In the case of the highly vascularized LS174T tumors, the accumulation was more confined to the periphery of the tumors, where angiogenesis is predominantly occurring. NIRF imaging revealed significant differences in accumulation kinetics between the models. In conclusion, this technology can serve as an in vivo biomarker for antiangiogenesis treatment and angiogenesis phenotyping.     

Carcinoid tumors: iodine-131 MIBG scintigraphy

Eighty-two patients with pathologically proved carcinoid tumors were examined with iodine-131 metaio-dobenzylguanidine (MIBG) scintigraphy. Localization scores of I-131 MIBG accumulation in the primary tumor or metastatic site ranged from 0 to 3+ on the basis of comparison with normal liver. I-131 MIBG uptake varied greatly in different patients with carcinoid tumors. The localization scores in known tumor sites were related to the location of the primary tumor in the stomach (1-3+ in two of five patients), pancreas (1-3+ in four of five patients), cecum (3+ in two of two patients), appendix (0 in one of one patient), jejunum (0 in one of one patient), Meckel diverticulum (3+ in one of one patient), terminal ileum (2-3+ in 19 of 28 patients), bronchus (3+ in one of nine patients), thymus (1+ in one of two patients), and unknown (2-3+ in 18 of 28 patients). Tumors of midgut origin concentrated I-131 MIBG more frequently than those of foregut origin. Uptake of I-131 MIBG was more likely if neurohumor levels, particularly serum serotonin, were elevated. There was no relationship of I-131 MIBG uptake to carcinoid syndrome. I-131 MIBG is useful in the determination of the location and extent of some carcinoid tumors, particularly those of midgut origin.     

Reactive oxygen intermediates induce regulated secretion of von Willebrand factor from cultured human vascular endothelial cells

Exocytosis from Weibel-Palade bodies, the secretory granules of vascular endothelial cells, causes the rapid release of von Willebrand factor (vWF), an adhesive glycoprotein involved in primary hemostasis, and cell surface expression of P-selectin, a membrane protein involved in neutrophil binding. Thus, exocytosis may represent a link between hemostasis and inflammation. We investigated the effect of reactive oxygen intermediates (ROIs) on vWF secretion. Incubation of cultured endothelial cells with xanthine oxidase (XO), which generates superoxide anions (O2-), induces a potent, rapid secretory response. However, vWF release was not observed in response to H2O2. Extracellular, subendothelial vWF deposits typically seen after exocytosis from Weibel-Palade bodies were observed after exposure to XO. XO caused a rapid, sustained increase in intracellular free calcium concentration ([Ca2+]i). vWF secretion was markedly inhibited by BAPTA- AM, a cell-permeant calcium chelator. Removal of extracellular calcium did not inhibit vWF release, although the sustained phase of the [Ca2+]i increase was suppressed. These results suggest that XO-induced vWF release is mediated by the initial increase in [Ca2+]i which is caused by calcium mobilization from intracellular stores rather than by calcium influx. Exocytosis from Weibel-Palade bodies may contribute to the pathogenic effect of ROIs in atherosclerosis and inflammation.     

Lymphoblastic lymphoma: an immunophenotype study of 26 cases with comparison to T cell acute lymphoblastic leukemia

A series of 26 lymphoblastic lymphomas (LLs) and 13 T cell acute lymphoblastic leukemias (ALLs) were investigated using a battery of monoclonal antibodies applied to tissue frozen sections. Twenty-one of the LLs were of T lineage. All but one of the T cell LLs were of immature thymic phenotype, mostly corresponding to stage II cortical thymocyte development. The T cell LLs expressed Leu-1 in 100%, Leu-4 and Leu-9 in 95%, and Leu-5 in 85% of the cases. The high percentage of Leu-4 expression in this series is probably due to detection of cytoplasmic antigen with our methods. One LL was of pre-B or B cell and two cases were of common ALL phenotype. Two cases were of undefined phenotype, expressing markers of both B and T cell differentiation. Pediatric cases showed a greater tendency toward T cell phenotype than did adult cases. The cases of T cell ALL were immunophenotypically similar to the cases of T cell LL but showed a tendency toward a more immature phenotype.     

Cyclophosphamide cardiotoxicity: an analysis of dosing as a risk factor

Patients who undergo bone marrow transplantation are generally immunosuppressed with a dose of cyclophosphamide (CYA) which is usually calculated based on the patient's weight. At these high doses of CYA, serious cardiotoxicity may occur, but definitive risk factors for the development of such cardiotoxicity have not been described. Since chemotherapeutic agent toxicity generally correlates with dose per body surface area, we retrospectively calculated the dose of CYA in patients transplanted at our institution to determine whether the incidence of CYA cardiotoxicity correlated with the dose per body surface area. Eighty patients who were to receive CYA 50 mg/kg/d for four days as preparation for marrow grafting underwent a total of 84 transplants for aplastic anemia, Wiskott-Aldrich syndrome, or severe combined immunodeficiency syndrome. Fourteen of 84 (17%) patients had symptoms and signs consistent with CYA cardiotoxicity within ten days of receiving 1 to 4 doses of CYA. Six of the 14 patients died with congestive heart failure. The dose of CYA per body surface area was calculated for all patients and the patients were divided into two groups based on daily CYA dose: Group 1, CYA less than or equal to 1.55 g/m2/d; Group 2, CYA greater than 1.55 g/m2/d. Cardiotoxicity that was thought to be related to CYA occurred in 1/32 (3%) of patients in Group 1 and in 13/52 (25%) patients in Group 2 (P less than 0.025). Congestive heart failure caused or contributed to death in 0/32 patients in Group 1 v 6/52 (12%) of patients in Group 2 (P less than 0.25). There was no difference in the rate of engraftment of evaluable patients in the two groups (P greater than 0.5). We conclude that the CYA cardiotoxicity correlates with CYA dosage as calculated by body surface area, and that patients with aplastic anemia and immunodeficiencies can be effectively prepared for bone marrow grafting at a CYA dose of 1.55 g/m2/d for four days with a lower incidence of cardiotoxicity than patients whose CYA dosage is calculated based on weight. This study reaffirms the principle that drug toxicity correlates with dose per body surface area.     

Proarrhythmic effects of a quinidine analog in dogs with chronic A-V block

Summary— The proarrhythmic effects of 3-hydroxy-hydroquinidine (3-OH-HQ) and quinidine were compared in a canine model of QT-dependent ventricular arrhythmias. Eight hypokalemic ([K+] ≤ 3.2 mmol/l) dogs with AV block (around 45 bpm) were given either drug in a randomized order at 2-day intervals. Each drug was given as two 1 hour doses, with a bolus (low dose: 5 mg/kg or high dose: 10 mg/kg) plus infusion (25 or 50 μg/kg/min) protocol. Propranolol infusion was combined with a third hour of the high dose infusion. Electrophysiologic measurements were performed at baseline and 30 minutes after the beginning of each dose and propranolol infusion, and proarrhythmic events were recorded 30 minutes before and during the experiment. Neither drugs altered the ventricular cycle length. Quinidine and 3-OH-HQ prolonged the QT interval similarly and significantly when paced at 60 bpm after the low dose (+ 39 ± 18 and + 28 ± 22 msec, respectively) and after the high dose (+ 51 ± 29 and + 50 ± 22 msec). Quinidine was more arrhythmogenic than 3-OH-HQ: 7/8 dogs (p ≤ 0.05) developed ventricular arrhythmias (isolated, repetitive ventricular beats, or polymorphic ventricular tachycardias) during quinidine infusion (low dose: 4 dogs) compared to 3/8 dogs (NS) during 3-OH-HQ infusion (low dose: 1 dog). Addition of propranolol-induced bradycardia (around 30 bpm) caused torsades de pointes (wave burst arrhythmias) or polymorphic ventricular tachycardias after both drugs (in 3 dogs after quinidine and in 2 dogs after 3-OH-HQ). Thus 3-OH-HQ was slightly less arrhythmogenic than quinidine in this model of torsades de pointes, but the addition of an extra favouring factor (bradycardia) reduced that difference.     

The origin of IgG production and homogeneous IgG components after allogeneic bone marrow transplantation

Pediatric recipients (n = 25) of an allogeneic bone marrow (BM) graft were selected on the basis of informative IgG allotype (Gm) differences between the BM donor and the recipient. To investigate the kinetics of the appearance of IgG of donor origin and the disappearance of IgG of recipient origin, G1m and G2m allotype levels were quantified in sera obtained at regular intervals between 3 months and 5 years after BM transplantation (BMT). For this quantification, a dot immunobinding assay (DIBA) has been developed. In 19 of 22 informative recipients, the Gm allotype distribution had reached the range of values expected on the basis of the Gm phenotype of the donor within 6 months after BMT. Remarkably, IgG of recipient origin persisted in 15 of 18 informative recipients until last follow up, ie, for several years after BMT. In addition to the origin of total IgG production, the origin of homogeneous IgG components (H-IgG) appearing after BMT was investigated. H-IgG of donor origin could be detected as early as 3 weeks after BMT, but also H-IgG of recipient origin were present in 8 of 13 informative recipients for a period of up to 1 year after BMT. We conclude that host-type IgG-producing cells were not eradicated by the (myeloablative) conditioning regimen and persisted in a high number of graft recipients. It is our hypothesis that lack of graft-versus-host disease (GVHD) in the majority of these recipients results in the persistence of IgG-producing cells of host origin. These observations may be relevant for the evaluation of patients who received allogeneic BMT for the treatment of multiple myeloma.