Improved detection of cell death in vivo with annexin V radiolabeled by site-specific methods.

Labeled annexin V is widely used to detect cell death in vitro and in vivo. Nearly all studies have been done with annexin V derivatized via amine-directed bifunctional agents; it was thought that these molecules retained full bioactivity compared with unmodified protein. We now show that this assumption is incorrect by measuring the affinity of annexin V for cells in vitro by quantitative calcium titration under conditions of low membrane occupancy. METHODS: Annexin V was modified with 4 different amine-directed agents: the N-hydroxysuccinimide esters of hydrazinonicotinic acid, mercaptoacetyltriglycine, and biotin; and with fluorescein isothiocyanate. RESULTS: In all cases, the membrane-binding affinity was decreased by derivatization, even at very low average stoichiometries. A statistical model based on the Poisson distribution accurately predicted the observed heterogeneity of derivatization as a function of average derivatization stoichiometry. This model also showed that multiply derivatized forms, which are the ones most likely to have compromised bioactivity, contributed disproportionately to the binding and imaging signals. The in vitro binding assay correctly predicted in vivo uptake in a mouse liver model of apoptosis for all proteins tested. The annexin V-128 protein, labeled at a single specific site at the N terminus, showed twice as much apoptosis-specific liver uptake as did all forms of annexin V derivatized randomly via amino groups. CONCLUSION: The membrane-binding activity of annexin V is much more sensitive to amine-directed chemical modification than previously realized. New annexin V molecules labeled by site-specific methods will greatly improve sensitivity for detecting cell death in vivo.     

Late pulmonary sequelae after childhood bone marrow transplantation

BACKGROUND: Respiratory function in transplanted children is important because of the long life expectancy of bone marrow transplant recipients, particularly children. Attention is now being focused on the late sequelae of treatment on organ system function. A few papers have been published but available data are somewhat conflicting. METHODS: A cross sectional study aimed at evaluating the late effects of transplantation on lung function was performed in a group of 52 young patients who were given autologous or allogeneic bone marrow transplants during childhood for haematological malignancies. RESULTS: No patients reported chronic respiratory symptoms. The distribution of respiratory function patterns showed that only 62% of patients had respiratory function within the normal limits; 23% had a restrictive pattern and 15% had isolated transfer factor impairment. The percentage of patients with lung function abnormalities was higher in those who (1) received a bone marrow transplant after two or three complete remissions compared with those who were transplanted immediately after the first remission (54% vs 21%; p < 0.02), (2) underwent allogeneic bone marrow transplantation rather than an autologous transplantation (45% vs 26%; p = 0.06), and (3) had a pulmonary infection compared with those without (56% vs 26%; p = 0.07). CONCLUSIONS: In spite of the absence of chronic respiratory symptoms there is a high prevalence of children with late pulmonary sequelae after bone marrow transplantation. Regular testing is recommended after transplantation, in particular in subjects at higher risk of lung injuries, such as those receiving transplants after more than one remission, those receiving allogeneic transplants, and those having suffered from pulmonary infections. When lung function abnormalities become apparent, long term follow up is necessary to see whether they become clinically relevant. All patients should remain non-smokers after transplantation and should have active early and aggressive treatment for respiratory illnesses.     

Mixed pituitary adenoma/craniopharyngioma: clinical, morphological, immunohistochemical and ultrastructural study of a case, review of the literature, and pathogenetic and nosological considerations

Mixed pituitary adenoma/craniopharyngiomas are very rare tumors. Their pathogenesis is still unclear and it is not known whether they are collision tumors derived from independent stem cells or whether they originate from a single stem cell undergoing divergent differentiation. The latter hypothesis is supported by the close commixture between the two tumor components with transition areas that has been previously described. However, “hybrid” cells with both pituitary adenoma and craniopharyngioma features have never been described. In this paper we report a case of mixed pituitary adenoma/craniopharyngioma observed in a 75-year-old woman presenting with diplopia and slight increase of serum prolactin, who underwent endoscopic endonasal trans-sphenoidal tumor resection. Histologically, the tumor was composed of a typical pituitary silent subtype 2 ACTH cell adenoma admixed with islands of adamantinomatous craniopharyngioma. Electron microscopy showed that, in addition to distinct silent subtype 2 ACTH and craniopharyngioma cells, there were “hybrid” cells, showing characteristics of both pituitary adenoma and craniopharyngioma, consisting of small dense secretory granules, bundles of cytoplasmic filaments, and desmosomes. This ultrastructural finding was also confirmed by the presence of cells showing nuclear p40 expression and chromogranin A immunoreactivity. The close commixture between the two components and the ultrastructural and immunohistochemical findings demonstrate a common histogenesis of the two components and support the classification of the neoplasm as a mixed tumor. The patient completely recovered and, 10 months after surgery, head MR confirmed the complete resection of the lesion.     

In vivo tumor angiogenesis imaging with site-specific labeled 99mTc-HYNIC-VEGF

Purpose We recently developed a cysteine-containing peptide tag (C-tag) that allows for site-specific modification of C-tag-containing fusion proteins with a bifunctional chelator, HYNIC (hydrazine nicotinamide)-maleimide. We then constructed and expressed C-tagged vascular endothelial growth factor (VEGF) and labeled it with HYNIC. We wished to test ^99mTc-HYNIC-C-tagged VEGF (^99mTc-HYNIC-VEGF) for the imaging of tumor vasculature before and after antiangiogenic (low continuous dosing, metronomic) and tumoricidal (high-dose) cyclophosphamide treatment. Methods HYNIC-maleimide was reacted with the two thiol groups of C-tagged VEGF without any effect on biologic activity in vitro. ^99mTc-HYNIC-VEGF was prepared using tin/tricine as an exchange reagent, and injected via the tail vein (200–300 μCi, 1–2 μg protein) followed by microSPECT imaging 1 h later. Results Sequencing analysis of HYNIC-containing peptides obtained after digestion confirmed the site-specific labeling of the two accessible thiol groups of C-tagged VEGF. Tumor vascularity was easily visualized with ^99mTc/VEGF in Balb/c mice with 4T1 murine mammary carcinoma 10 days after implantation into the left axillary fat pad in controls (12.3±5.0 tumor/bkg, n=27) along with its decrease following treatment with high (150 mg/kg q.o.d. ×4; 1.14±0.48 tumor/bkg, n=9) or low (25 mg/kg q.d. ×7; 1.03±0.18 tumor/bkg, n=9) dose cyclophosphamide. Binding specificity was confirmed by observing a 75% decrease in tumor uptake of ^99mTc/biotin-inactivated VEGF, as compared with ^99mTc-HYNIC-VEGF. Conclusion ^99mTc can be loaded onto C-tagged VEGF in a site-specific fashion without reducing its bioactivity. ^99mTc-HYNIC-VEGF can be rapidly prepared for the imaging of tumor vasculature and its response to different types of chemotherapy.     

ELR+-CXC chemokines and their receptors in early metanephric development

Although originally identified as mediators of inflammation, it is now apparent that chemokines play a fundamental role in tissue development. In this study, ELR(+)-CXC chemokine family members CXCL2 and CXCL7, along with their preferred receptor CXCR2, were expressed at the earliest stages of metanephric development in the rat, and signaling through this receptor was required for the survival and maintenance of the undifferentiated metanephric mesenchyme (MM). A specific antagonist of the CXCR2 receptor SB225002 induced apoptosis in this population but did not affect more mature structures or cells in the ureteric bud. CXCL7 treatment of isolated MM elicited an angiogenic response by upregulation of matrix metalloprotease 9 and endothelial and mesangial markers (platelet-endothelial cell adhesion molecule, Megsin, Thy-1, PDGF receptor alpha, and vascular alpha-actin) and induced SB225002-sensitive cell invasion through a matrix. Because Wilms' tumor cells may similarly depend on CXCR2 signaling for survival, primary tumor samples were analyzed, and 15 of 16 Wilms' tumors were found to be CXCR2 positive, whereas grossly normal kidney tissues from tumor patients or renal cell carcinomas were CXCR2 negative. Furthermore, cell lines derived from Wilms' tumors but not those from renal cell carcinomas were sensitive to SB225002-induced apoptosis. These data provide evidence for a prosurvival and proangiogenic role of ELR(+)-CXC chemokines and their receptor CXCR2 during metanephric development and suggest a novel mechanism for chemotherapeutic intervention in Wilms' tumor.     

Characterization of fibroblast-specific protein 1 in pulmonary fibrosis

Because fibroblasts produce collagen and other extracellular matrix components that are deposited during tissue fibrosis, defining the behavior of these cells is critical to understanding the pathogenesis of fibrotic diseases. We investigated the utility of fibroblast-specific protein 1 (FSP1), a member of the calmodulin S100 troponin C superfamily, for identifying lung fibroblasts in a murine model of pulmonary fibrosis induced by intratracheal administration of bleomycin. Protein and mRNA expression of FSP1 was minimal in untreated lungs, but increased by 1 week after bleomycin administration and remained increased at 2 and 3 weeks after treatment. By immunohistochemistry, the number of FSP1(+) cells increased in a dose-dependent manner in the lungs after bleomycin treatment. Colocalization of alpha1 procollagen and FSP1 in interstitial cells demonstrated that FSP1(+) fibroblasts contribute to the deposition of collagen after bleomycin administration. In primary lung cell cultures, lung fibroblasts, but not macrophages or type II alveolar epithelial cells, expressed FSP1. FSP1 also identified fibroblasts in lung biopsy specimens from patients with documented usual interstitial pneumonitis. Therefore, FSP1 is an improved marker for lung fibroblasts that could be useful for investigating the pathogenesis of pulmonary fibrosis.