Perils and deficiencies of the European Convention on Human Rights and Biomedicine

The authors analyze deficiencies and perils of the European Convention on Human Rights and Biomedicine, in particular the concept of human rights as given by natural law and the Convention's stand on germline therapy and its refutation of therapeutic enhancement.

Comparison of pig, human and rat hepatocytes as a source of liver specific metabolic functions in culture systems--implications for use in bioartificial liver devices

The limited availability of human hepatocytes results in the use of animal cells in most bioartificial liver support devices. In the present work, clinically relevant liver specific metabolic activities were compared in rat, pig and human hepatocytes cultured on liver-derived biomatrix to optimize the expression of differentiated functions. Pig hepatocytes showed higher rates of diazepam metabolism (2.549+/-0.821 microg/h/million cells vs. 0.474+/-0.079 microg/h/million cells rats, p<0.005, and vs. 0.704+/-0.171 microg/h/million cells in man, p<0.005) and of bilirubin conjugation (21.60116+/-8.433237 micromoles/l/24 h vs. 6.786809+/-2.983758 in man, p<0.001 and vs. 9.956538+/-1.781016 micromoles/l/24 h in rats, p<0.005). Urea synthesis was similar in pig and in human hepatocytes (150+/-46.3 vs. 144.8+/-21.46 nmoles/h/million cells) and it was lower in rats (84.38+/-35.2; p<0.001 vs. man, p<0.02 vs. pig). High liver specific metabolic activities in cultured pig hepatocytes further support their use as a substitue for human cells in bioartificial liver devices.

Phage Display Libraries as a Source of Tumour-Targeting Agents

One way to improve the therapeutic index of anti-cancer agents would be to target them to the tumour site, thereby sparing normal tissues. Tumour targeting approaches heavily rely on the availability of specific binding molecules, recognising markers which are selectively expressed in the tumour environment. The display of antibody repertoires on the surface of filamentous phage, together with efficient selection-amplification schemes, allows the isolation of good-quality human antibodies against virtually any molecular target. This article illustrates how antibody phage technology has been used in our laboratory for the isolation of tumour targeting agents. Furthermore, we present recent developments in the display of repertoires of small globular proteins on filamentous phage, aimed at the isolation of specific binding molecules with molecular weight < 10000 Dalton.

Isolation of anti-angiogenesis antibodies from a large combinatorial repertoire by colony filter screening

We describe here a method, based on iterative colony filter screening, for the rapid isolation of binding specificities from a large synthetic repertoire of human antibody fragments in single-chain Fv configuration. Escherichia coli cells, expressing the library of antibody fragments, are grown on a porous master filter, in contact with a second filter coated with the antigen, onto which antibodies secreted by the bacteria are able to diffuse. Detection of antigen binding on the second filter allows the recovery of a number of E.coli cells, including those expressing the binding specificity of interest, which can be submitted to a second round of screening for the isolation of specific monoclonal antibodies. We tested the methodology using as antigen the ED-B domain of fibronectin, a marker of angiogenesis. From an antibody library of 7 x 10(8) clones, we recovered a number of specifically-binding antibodies of different aminoacid sequence. The antibody clone showing the strongest enzyme-linked immunosorbent assay signal (ME4C) was further characterised. Its epitope on the ED-B domain was mapped using the SPOT synthesis method, which uses a set of decapeptides spanning the antigen sequence synthesised and anchored on cellulose. ME4C binds to the ED-B domain with a dissociation constant K:(d) = 1 x 10(-7) M and specifically stains tumour blood vessels, as shown by immunohistochemical analysis on tumour sections of human and murine origin.

Liver transplantation with vena cava in situ and selective use of temporary portacaval shunt or portal clamping

BACKGROUND/AIMS

The recipient hepatectomy with vena cava in situ in liver transplantation has overcome the need of venous-venous bypass thanks to temporary porta caval shunt or portal clamping.

METHODOLOGY

150 orthotopic liver transplants in 137 patients were performed and the vena cava in situ technique was used in 142 (venous bypass in 7, temporary porta caval shunt in 49, portal clamping in 87). The suprahepatic cava veins anastomosis was performed with Belghiti in 97 and piggyback techniques in 45.

RESULTS

There were no differences in operative and warm ischemia times nor in blood requirements, while a greater stability of body temperature was documented in the vena cava In Situ group: in the latter temporary porta caval shunt preserved the temperature better than portal clamping (P < 0.01). In anhepatic phase mean artery pressure decreased in veno-venous bypass and increased in the vena cava In situ groups (P < 0.01). The venous return and the cardiac performances (anhepatic phase) were better preserved in the vena cava In Situ group. (P < 0.0001).

CONCLUSIONS

Temporary portal caval shunt or portal clamping and piggyback or Belgiti Techniques allow a better hemodynamic stability through out the procedure, obviating the need for veno-venous bypass or fluid overload, if selectively used.

Targeted delivery of tissue factor to the ED-B domain of fibronectin, a marker of angiogenesis, mediates the infarction of solid tumors in mice

The selective thrombosis of tumor blood vessels, leading to the starvation and subsequent death of tumor cells, is an attractive anticancer strategy. Here we report that a fusion protein, consisting of an antibody fragment specific for the oncofoetal ED-B domain of fibronectin fused to the extracellular domain of tissue factor, selectively targets tumor blood vessels in vivo. Furthermore, this fusion protein mediates the complete and selective infarction of three different types of solid tumors in mice. At the highest doses administered, complete tumor eradication was observed in 30% of the mice treated without apparent side effects. These results are of therapeutic relevance because the ED-B domain of fibronectin, a naturally occurring marker of angiogenesis identical in mouse and man, is expressed in the majority of aggressive solid tumors but is undetectable in normal vessels and tissues.

A Strategy for the Identification of Differentially Expressed Proteins Secreted by Fibroblasts

Monoclonal antibodies, which recognise markers of the modified tumour extracellular matrix, may be valuable tools for the diagnosis and therapy of cancer. The pattern of expression of some good-quality tumour-associated antigens is known to be regulated by intracellular pH. In this article, a strategy is described for the isolation of human antibodies specific for proteins which are differentially secreted by fibroblasts at different pH values. We panned a large synthetic antibody phage library against biotinylated proteins secreted by normal human dermal fibroblasts, cultured at pH 7.5, in the presence or in the absence of a molar excess of unbiotinylated proteins, secreted by fibroblasts cultured at pH 6.7. A panel of monoclonal antibodies was isolated, whose reactivity was tested by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry.

The use of phage display for the development of tumour targeting agents

One way to improve the selectivity of therapeutic molecules in clinical oncology would be to target them on the tumour site, thereby sparing normal tissues. The development of targeted therapeutic methodologies relies in most cases on the availability of binding molecules specific for tumour-associated markers. The display of repertoires of polypeptides on the surface of filamentous phage, together with the efficient selection-amplification of the desired binding specificities using affinity capture, represents an efficient route towards the isolation of specific peptides and proteins that could act as vehicles for tumour targeting applications. Most investigations in this area of research have so far been performed with phage derived recombinant antibodies, which have been shown to selectively target tumour-associated markers both in preclinical animal models and in the clinic. However, future developments with other classes of polypeptides (small constrained peptides, small globular proteins) promise to be important for the selective delivery of therapeutic agents to the tumour site.

Role of transarterial chemoembolization before liver resection for hepatocarcinoma

The aim of this study was to clarify whether chemoembolization (TACE) before liver resection (LR) can reduce postoperative hepatocellular carcinoma (HCC) recurrence and improve disease-free and overall survival. Eighty-nine patients with tumor-stage (TNM) I-II HCC were evaluated for LR. Patients were prospectively allocated to LR alone or TACE plus LR based on their place of residence. Twenty nonlocal patients (24%) were selected for LR, while 69 (77.5%) local patients were selected for TACE plus LR. Following TACE, the tumor stage could be confirmed in only 20 patients (29%) who then underwent LR. Operative mortality was 0%, but in the TACE-LR group, 3 patients died of liver failure between 2 and 5 months after surgery. Early recurrence (<24 months) was 59% for LR versus 20% for TACE plus LR (P <.05). Late recurrence was 18% for LR versus 10% for TACE plus LR (P = not significant [NS]). The overall recurrence rate was 76% for LR versus 30% for TACE plus LR (P <.02). Death due to HCC recurrence was 70% for LR versus 15% for TACE plus LR (P <.05). The overall 1- and 5-year survival rates did not differ significantly (71% to 38% for LR v 85% to 43% for TACE + LR; P = NS), whereas the difference in 1- and 5-year disease-free survival was highly significant (64% to 21% for LR v 82% to 57% for TACE + LR; P <.02). TACE was able to improve the HCC staging process and significantly reduce the incidence of early and overall HCC recurrence and related death after LR; it improved the disease-free interval, but not the overall survival, due to an increase in liver failure in the first 5 months.

Inhibition of tumor angiogenesis by a single-chain antibody directed against vascular endothelial growth factor

Monoclonal antibody (Ab) directed against the vascular endothelial growth factor, one of the major inducers of angiogenesis, can inhibit tumor growth in mice. Treatment of cancer patients with monoclonal Ab requires large-scale production of the clean Ab and frequent application of the Ab. This might be improved by using single-chain Ab fragments (scFvs), which can be produced in large quantities in bacteria and are attractive for gene therapeutic approaches. Here we describe anti-vascular endothelial growth factor scFvs derived from a human phage-display library able to block the vascularization of the chorioallantoic membrane of chick embryos and reduce the growth of s.c. tumors in nude mice. This work opens the way to develop gene therapy-based strategies using a scFv to treat angiogenesis-dependent diseases.

[Care at the patient's bedside. Non-invasive bioethics]

This paper aims at describing the circumstances of the birth of Bioethics. In the first section, the paper points out some historical data supporting the widely diffused opinion according to which Bioethics started in the USA at the beginning of the '70s. In the second section, one of the most important factors in the birth of Bioethics is discussed: namely, the changes in medical enterprise and health care ethics. In the third section the impact of Bioethics on clinical medicine at the bedside is discusses, and, in the last section, one of the most important practical application of bioethical reflection is presented: the creation of Hospital Ethics Committees.

Highly fluorescent protein labeling using dendritic peptide derivatives

Non-specific fluorescent dyes and photosensitizers are routinely used in clinical practice for the photodetection and photoablation of superficial lesions. Future applications in photomedicine are likely to rely on the selective delivery of photoactive compounds to diseased areas, using specific targeting agents such as antibodies. This fact underlines the need for methods that allow the chemically defined conjugation of several photoactive molecules to a single protein 'vehicle', with full retention of binding affinity. Here, we present methods for the site-specific fluorescent labeling of proteins using dendritic peptides, which had been chemically modified with multiple molecules of fluorescein. Branched peptide derivatives can be stably conjugated to proteins either by reaction with suitable free reactive groups or by using the high-affinity non-covalent interaction between calmodulin and a specific binding peptide. Chemical modification of proteins with one, two or four molecules of fluorescein resulted in a proportional increase in protein fluorescence.

Laparoscopic surgery after orthotopic liver transplantation

Laparoscopic surgery is currently a widely accepted approach to several surgical fields because of its advantages in terms of postoperative pain reduction and easy patient recovery. This approach may be useful even in solid-organ transplantation surgery as a diagnostic or treatment procedure in some surgical complications. From July 1991 to December 1998, we performed 142 liver transplantations on 129 patients. During the postoperative period, many complications occurred. Here we report two cases of intestinal occlusion caused by adhesions and three cases of lymphocele, all approached with laparoscopic surgery. In all cases but one, we were able to complete the surgery by laparoscopic means; in one of the two occlusions, the procedure was switched to laparotomy because of a choledochojejunal anastomosis lesion. The three cases of lymphocele must be considered in a particular manner because such cases, to our knowledge, have never been described in the literature. They always presented with a late-onset right pleural effusion and were located in the retrohepatic, retrogastric, and left paracaval areas, close to the esophageal hiatus. In conclusion, we believe a laparoscopic approach is a useful strategy to solve some surgical complications in patients who underwent orthotopic liver transplantation; however, the use of laparoscopic surgery in this field is strictly connected to the surgeon's experience and versatility.

Infrared photodetection for the in vivo localisation of phage-derived antibodies directed against angiogenic markers

Angiogenesis, the formation of new blood vessels from pre-existing ones, is a characteristic process which underlies many diseases, including cancer, rheumatoid arthritis and blinding ocular disorders. Antibodies capable of selective targeting and occlusion of neovasculature would open diagnostic and therapeutic opportunities. We have recently demonstrated that phage-derived human antibody fragments with high affinity for the extra-domain B (ED-B) of fibronectin, a marker of angiogenesis, selectively localise in new-forming blood vessels upon intravenous injection. Here, we show that infrared fluorescence methodologies nicely complement radioactive techniques for the study of the antibody-mediated targeting of angiogenesis in a variety of animal models. Methods are presented for the construction and use of infrared fluorescence imagers, as well as for the production and characterisation of recombinant antibodies labeled with infrared fluorophores.

Selective targeting and photocoagulation of ocular angiogenesis mediated by a phage-derived human antibody fragment

Molecules that selectively target and occlude new blood vessels would be useful for diagnosis and treatment of pathologies associated with angiogenesis. We show that a phage-derived human antibody fragment (L19) with high affinity for the ED-B domain of fibronectin, a marker of angiogenesis, selectively localizes to newly formed blood vessels in a rabbit model of ocular angiogenesis. The L19 antibody, chemically coupled to a photosensitizer and irradiated with red light, mediates complete and selective occlusion of ocular neovasculature and promotes apoptosis of the corresponding endothelial cells. These results demonstrate that new ocular blood vessels can be distinguished immunochemically from preexisting ones and suggest that the targeted delivery of photosensitizers may be effective in treating angiogenesis-related pathologies.

A high-affinity human antibody that targets tumoral blood vessels

Angiogenesis is a characteristic feature of many aggressive tumors and of other relevant disorders. Molecules capable of specifically binding to new-forming blood vessels, but not to mature vessels, could be used as selective vehicles and would, therefore, open diagnostic and therapeutic opportunities. We have studied the distribution of the ED-B oncofetal domain of fibronectin, a marker of angiogenesis, in four different tumor animal models: the F9 murine teratocarcinoma, SKMEL-28 human melanoma, N592 human small cell lung carcinoma, and C51 human colon carcinoma. In all of these experimental models we observed accumulation of the fibronectin isoform containing the ED-B domain around neovascular structures when the tumors were in the exponentially growing phase, but not in the slow-growing phase. Then we performed biodistribution studies in mice bearing a subcutaneously implanted F9 murine teratocarcinoma, using a high-affinity human antibody fragment (L19) directed against the ED-B domain of fibronectin. Radiolabeled L19, but not an irrelevant anti-lysozyme antibody fragment (D1.3), efficiently localizes in the tumoral vessels. The maximal dose of L19 accumulated in the tumor was observed 3 hours after injection (8.2% injected dose per gram). By virtue of the rapid clearance of the antibody fragment from the circulation, tumor-to-blood ratios of 1.9, 3.7, and 11.8 were obtained at 3, 5, and 24 hours, respectively. The tumor-targeting performance of L19 was not dose-dependent in the 0.7 to 10 microg range of injected antibody. The integral of the radioactivity localized in tumoral vessels over 24 hours was greater than 70-fold higher than the integral of the radioactivity in blood over the same time period, normalized per gram of tissue or fluid. These findings quantitatively show that new-forming blood vessels can selectively be targeted in vivo using specific antibodies, and suggest that L19 may be of clinical utility for the immunoscintigraphic detection of angiogenesis in patients.

The use of biosensor technology for the engineering of antibodies and enzymes

Recently developed scientific instrumentation featuring surface plasmon resonance detection allows the detection of biomolecular interactions in real time and without chemical modification of the binding partners. These biosensors are proving invaluable tools in protein engineering, particularly in research aimed at the isolation and improvement of protein binders and catalysts from macromolecular repertoires containing billions of individual members. This article reviews the use of biosensor technology for the isolation and characterization of engineered antibodies and enzymes.

Identification of a glioblastoma-associated tenascin-C isoform by a high affinity recombinant antibody

Tenascin-C exists in several polymorphic isoforms due to alternative splicing of nine fibronectin-like type III repeats. Large Tenascin-C isoforms are present in almost all normal adult tissues but are upregulated in fetal, regenerating, and neoplastic tissues. Here, we report a human antibody fragment, TN11, derived from a phage library with high affinity for the spliced repeat C and demonstrate that this repeat is undetectable in normal adult tissues, barely detectable or undetectable in breast, lung and gastric carcinomas, meningioma, and low grade astrocytoma, but extremely abundant in high grade astrocytoma (grade III and glioblastoma), especially around vascular structures and proliferating cells. The antibody appears to have potential for development of a therapeutic agent for patients with high grade astrocytoma.

NMR structure of the human oncofoetal fibronectin ED-B domain, a specific marker for angiogenesis

BACKGROUND

The process of angiogenesis (i.e. the formation of new blood vessels from pre-existing ones) is fundamental to physiological processes such as reproduction, development and repair, as well as to pathological conditions such as tumor progression, rheumathoid arthritis and ocular disorders. The oncofoetal ED-B domain, a specific marker of angiogenesis, consists of 91 amino acid residues that are inserted by alternative splicing into the fibronectin (FN) molecule.

RESULTS

The NMR structure of the ED-B domain is reported and reveals important differences from other FN type III domains. A comparison of the ED-B domain with the crystal structure of a four-domain FN fragment shows the novel features of ED-B to be located in loop regions that are buried at interdomain interfaces, and which therefore largely determine the global shape of the FN molecule. The negatively charged amino acids in this highly acidic protein are uniformly distributed over the molecular surface, with the sole exception of a solvent-exposed hydrophobic patch that represents a potential specific recognition site. Epitope mapping with 82 decapeptides that span the ED-B sequence revealed that three ED-B-specific monoclonal antibodies, which selectively target newly forming blood vessels in tumor-bearing mice, bind to adjacent regions on the ED-B surface.

CONCLUSIONS

The NMR structure enables the identification of a large surface area of the ED-B domain that appears to be accessible in vivo, opening up new diagnostic and therapeutic opportunities. Furthermore, the mapping of specific monoclonal antibodies to the three-dimensional structure of the ED-B domain, and their use in angiogenesis inhibition experiments, provides a basis for further investigation of the role of the ED-B domain in the formation of new blood vessels.

On the concept of eugenics: preliminaries to a critical appraisal

This paper's main issue is linked to what can be foreseen as the increasing capability of medical genetics to modify the genetic composition of the human species through direct interventions in the human genome for medical and non-medical purposes, i.e., the "risk" of a resurgence of eugenics. In current discussions on the topic (briefly presented in the first section), the "phantom of eugenics" is raised several times, but there is a great deal of confusion on what counts as eugenics, partly because of broad conceptual disagreement over the notion itself. Furthermore, according to some scholars there is no hope of overcoming this unsatisfactory conceptual uncertainty. Partly challenging this opinion, the second and third sections of this paper attempt to identify some basic features which could be seen as intrinsically linked to the notion of eugenics, with the aim of reducing the range of conceptual disagreement as a preliminary step in bringing into focus what exactly is wrong with practicing eugenics. The subsequent sections deal with the substantive issue of whether or not to practice eugenics from the point of view of the interest of future generations in the human species' genetic composition. The main moral arguments for and against eugenics are examined from the point of view of our obligations towards future generations, and the conclusion is in favor of a cautious "open-door" position.

A strategy for the isolation of catalytic activities from repertoires of enzymes displayed on phage

We have aimed at developing a general methodology for the isolation of enzymatic activities from large repertoires of protein displayed on the surface of a filamentous phage. When selecting for protein binders by phage display, phage particles with suitable specificities are physically isolated by affinity capture and amplified by bacterial infection. Selection for catalysis mediated by enzymes displayed on filamentous phage is more difficult, as reaction products (which represent the biochemical memory of the reaction catalysed by the phage particle) diffuse away after the reaction is complete. We reasoned that if we were able to anchor the reaction products on the phage surface, the catalytically active phages could then be physically isolated using specific anti-product affinity reagents. We achieve the conditional anchoring of reaction substrates and products on phage by displaying enzyme-calmodulin chimeric proteins on filamentous phage as gene III fusions. Such phage particles can be targeted in a stable fashion (koff<10(-4) s(-1)) by chemical derivatives of a calmodulin-binding peptide. The peptide-phage complexes are stable in purification procedures such as capture with magnetic beads and polyethylene glycol precipitation, and can be conditionally dissociated by addition of calcium chelators. Glutathione-S-transferase and an endopeptidase were used in model selection experiments to demonstrate that it is possible to isolate catalytic activities from calmodulin-tagged enzymes displayed on filamentous phage, with enrichment factors >50 per round of selection.

Towards the design of an antibody that recognises a given protein epitope

We have explored the possibility of designing repertoires of antibodies complementary to a given protein epitope, specifically the face of the ribonuclease inhibitor barstar that binds to the enzyme barnase. An antibody repertoire was created by mutation of ten residues in the hypervariable loops of a synthetic antibody fragment and displayed on filamentous bacteriophage. The positions of three of the ten residues of the antibody (VL 32, 50 and 94) were chosen to match a triangle of three negative charges on the face of barstar and mutated to favour residues of opposite charge or those with hydrogen-bonding potential. The other seven residues, chosen to allow for variation in the surface of interaction, were mutated at random. One of the antibody fragments isolated after selection of the repertoire (10(8) clones per library) was shown to bind to barstar with an affinity of 1.0x10(-7) M and the binding was competed by barnase. Furthermore, the binding of the antibody to barstar was highly sensitive to mutation of any of five residues of barstar known to contact barnase. This indicates that it may be possible, by a combination of design and selection, to build antibodies to a given epitope.

Increased binding affinity and valence of recombinant antibody fragments lead to improved targeting of tumoral angiogenesis

The formation of new blood vessels (angiogenesis) is an important step in tumor progression. Molecules capable of selectively targeting markers of angiogenesis may offer opportunities for the in vivo imaging of aggressive tumors and for the delivery of toxic agents to the tumoral vasculature. Using antibody phage display libraries and combinatorial mutagenesis, we isolated single-chain Fv antibody fragments, which recognize with different affinities the same epitope of the ED-B domain of fibronectin, a marker of angiogenesis. Two single-chain Fv fragments, E1 and L19, with dissociation constants of 41 nM and 0.054 nM, respectively, were investigated for their ability to target F9 murine teratocarcinoma grafted s.c. in nude mice when injected i.v. in either monomeric or homodimeric form (Mr 27,000 and 54,000, respectively). Biodistribution studies, performed at two time points (4 h and 24 h) with radiolabeled samples, showed that the higher affinity antibody targets the tumor significantly better than the lower affinity one, in terms both of tumor:organ ratios and of the amounts of antibody delivered to the tumor. In particular, more than 20% of the injected dose of dimeric L19 accumulated per gram of tumor at 4 h; the tumor:organ ratios at 4 h and 24 h were in the (2.1-8.6):1 and (10.3-29.4):1 range, respectively. This study demonstrates that, although vasculature represents only a small fraction of the total tumor mass, anti-ED-B antibodies can selectively target tumors in vivo and that this process is particularly efficient if very high-affinity binders are used.

[Bioethics: history and problems]

This paper aims at describing the circumstances of the birth of bioethics. In the first section, the paper stresses some historical data supporting the widely diffused opinion according to which bioethics arose in the USA at the beginning of the Seventies. In the second, two of the most important factors in the birth of bioethics are discussed: namely, the possibilities opened by genetic engineering and the changes in the medical enterprise and health care ethics. In the third section the paper discusses one of the most important practical realization of bioethics: the creation of ethical committees.

Design and use of a phage display library. Human antibodies with subnanomolar affinity against a marker of angiogenesis eluted from a two-dimensional gel

We report the construction and the use of a phage display human antibody library (>3 x 10(8) clones) based on principles of protein design. A large repertoire of functional antibodies with similar properties was produced by appending short variable complementarity-determining region 3 (CDR3) onto the two antibody germ line segments most frequently found in human antibodies. With this strategy we concentrated sequence diversity in regions of the antibody structure that are centrally located in the antigen binding site, while leaving residues in more peripheral positions available for further mutagenesis aimed at improving the affinity of the selected antibodies. In addition, the library was tested by selecting antibodies against six biologically relevant antigens. Using only 0.3 microg of antigen eluted from a two-dimensional gel spot, we isolated binders specific for the ED-B domain of fibronectin, a marker of angiogenesis. These antibodies recognize the native antigen with affinities in the 10(7)-10(8) M-1 range, and perform well in immunosorbent assays, in two-dimensional Western blotting and in immunohistochemistry. The affinity of one anti-ED-B antibody was improved by 27-fold by combinatorially mutating six strategically selected residues in the heavy chain variable domain. A further 28-fold affinity improvement could be achieved by mutating residues 32 and 50 of the light chain. The resulting antibody, L19, bound to the ED-B domain of fibronectin with very high affinity (Kd = 54 pM), as determined by real-time interaction analysis with surface plasmon resonance detection, band shift analysis, and by competition experiments with electrochemiluminescent detection.

Preparation of phage antibodies to the ED-A domain of human fibronectin

The fibronectin (FN) isoform containing the alternative spliced ED-A domain is much more expressed in fetal, tumoral, and regenerating tissues than in normal adult tissues. The ED-A containing FN is up-regulated by numerous cytokines, such as TGF-beta, and, although in normal adult liver the ED-A domain is undetectable, in regenerating rat liver the expression of ED-A is increased and mediates the conversion of fat storing cells to myofibroblasts. Here we describe the selection from a phage display library and the characterization of human antibody fragments directed against the ED-A sequence of FN. As they can be easily radiolabeled with 32P, these antibodies are very highly sensitive reagents for the determination of ED-A levels in tissues and biological fluids; in fact, use of these scFv induced a more than 10-fold increase in sensitivity with respect to the murine monoclonal IST-9. The possibility of preparing a range of human engineered antibodies should facilitate the development of antibody reagents with suitable pharmacokinetics, valency, functional affinity, and effector functions and that could be useful for clinical purposes.

Cerebral aspergillosis in a liver transplant recipient: a case report of long-term survival after combined treatment with liposomal amphotericin B and surgery

Cerebral aspergillosis is a life-threatening complication in liver transplant recipients, with mortality rates approaching 100%; treatment with amphotericin B is of limited efficacy because of its poor distribution in the cerebrospinal fluid and its systemic side effects. We report the case of a liver transplant recipient who developed recurrent cerebral Aspergillus fumigatus infection, and was successfully treated by combined surgical excision of the lesion and administration of liposomal amphotericin B. This first report of long-term complication-free survival in a liver transplant recipient suggests that therapy with liposomal amphotericin B may reduce the risk of recurrence of cerebral aspergillosis in these immunocompromised patients.

Tumor targeting potential of the monoclonal antibody BC-1 against oncofetal fibronectin in nude mice bearing human tumor implants

BACKGROUND

The immunoglobulin G1 (IgG1) monoclonal antibody (MoAb) BC-1 detects human oncofetal fibronectin, which has extremely restricted distribution in normal adult tissues and is highly expressed in fetal and tumor tissues.

METHODS

We studied the biodistribution of 125I-labeled MoAb BC-1 in nude mice bearing subcutaneous human tumor implants of U87MG high-grade astrocytoma and SKMel28 melanoma. 125I-BC-1 was injected either intraperitoneally (i.p.) or intravenously (i.v.), and biodistribution was measured up to 144 hours after injection. In animals bearing SKMel28 implants, tumor targeting was also evaluated by in vivo imaging of the whole mouse by using a dedicated device based on transmitted light excitation after i.v. injection of MoAb BC-1 conjugated with the infrared fluorophore, CY7-bis(N-hydroxy-succinimido)-ester.

RESULTS

125I-BC-1 showed favorable uptake in the human tumor implants, reaching a maximum of 5.27 +/- 0.48% ID/g in the U87MG astrocytoma (72 hours after i.p. injection). The highest uptake in the SKMel28 melanoma implants was 3.49 +/- 0.25% ID/g (24 hours after i.v. injection). Microautoradiography of tumor specimens obtained after administration of 125I-BC-1 clearly showed radioactivity uptake within the two tumors replicating the same pattern of distribution as that of the oncofetal fibronectin shown by immunohistochemistry with MoAb BC-1. Nonspecific uptake of 125I-BC-1 in the bone marrow and skeletal muscle was much lower than in the tumors. In vivo imaging with the fluorophore-labeled MoAb clearly visualized the tumor implants 72-120 hours after i.v. injection.

CONCLUSIONS

The experimental results obtained in this study demonstrate the favorable tumor targeting potential in vivo of the radiolabeled MoAb BC-1, a useful marker of neo angiogenesis induced by cancer.

Targeting by affinity-matured recombinant antibody fragments of an angiogenesis associated fibronectin isoform

The oncofetal fibronectin (B-FN) isoform is present in vessels of neoplastic tissues during angiogenesis but not in mature vessels. B-FN could therefore provide a target for diagnostic imaging and therapy of cancer. Phage display libraries have been used to isolate human antibody fragments with pan-species recognition of this isoform. We describe the use of these fragments in nude mice to target an aggressive tumor (grafted F9 murine teratocarcinoma). Imaging in real time was done by infrared photodetection of a chemically coupled fluorophore. The targeting was improved by use of affinity-matured fragments with low kinetic dissociation rates (koff = 1.5 x 10(-4) s-1) and also by engineering dimeric fragments via a C-terminal amphipathic helix.

Hierarchical affinity maturation of a phage library derived antibody for the selective removal of cytomegalovirus from plasma

Recombinant antibody fragments can be produced in large quantities using bacterial expression systems and could potentially be useful for the generation of biofilters for the selective removal of viral particles from fluids. A human single chain-Fv antibody library, derived from synthetic repertoires of germ line VH-gene segments rearranged in vitro and paired to a single light chain (Nissim et al., 1994, EMBO J., 13, 692-698), has recently been used to isolate hundreds of different binding specificities by panning with antigen. Antibodies from this library typically have affinities in the 10(6)-10(7) M-1 range. Occasionally, better binders are isolated but at other times the affinities recovered are poor. In the latter situation binding cannot be detected with soluble antibodies, but only by high-avidity display of multiple copies of antibodies on phage. By panning with human cytomegalovirus (HCMV)-coated immunotubes, we have isolated a number of antibody clones from this library that bound to the antigen only if displayed on the filamentous phage, but not in soluble form. One of these clones was selected for an affinity maturation procedure, achieved by combinatorial mutagenesis of the complementarity determining region 3 (CDR3) of the antibody light chain, followed by selection of the resulting library for HCMV binding. By this means, we were able to isolate a number of binders, some of which exhibited specific HCMV binding in soluble form. The clone that gave the strongest ELISA signal was expressed in bacteria, purified in solution, characterised using a novel capture methodology with surface plasmon resonance detection on a BIAcore instrument and used for the production of an immunofilter for the removal of HCMV form human serum. The filter removed more than 99% of applied HCMV in 10 min circulation time, while the amount of HCMV retained non-specifically in a cartridge derivatised with a non-specific antibody was less than 10% under similar conditions.

Epstein-Barr virus-associated post-transplant lympho-proliferative disease of donor origin in liver transplant recipients

BACKGROUND/AIMS

Post-transplant lymphoproliferative disease, a potential complication of solid organ transplantation, occurs in about 3% of orthotopic liver transplant recipients. We report the genetic and virological characterization of two cases of post-transplant lymphoproliferative disease that occurred early (4 and 6 months) after orthotopic liver transplant as large-cell non-Hodgkin's lymphomas located at the hepatic hilum.

METHODS

Lymphomatous tissues were analyzed for clonality and presence of Epstein-Barr virus (EBV) sequences by Southern blot, polymerase chain reaction, and in situ hybridization techniques.

RESULTS

The tumors in both cases were sustained by a clonal proliferation of B lymphocytes containing type A EBV DNA. Moreover, in situ hybridization with a digoxigenin-labeled EBV-specific probe evidenced a strong nuclear signal in most of the neoplastic cells. DNA microsatellite analysis at three different loci detected alleles of donor origin in both tumor samples, suggesting that the neoplastic B cells were of donor origin.

CONCLUSIONS

EBV-infected donor B lymphocytes might be responsible for intragraft post-transplant lymphoproliferative disease in orthotopic liver transplant recipients. As 20 to 30% of post-transplant lymphomas involve the graft itself, donor-derived post-transplant lymphoproliferative disease might be more frequent than presently appreciated. Prospective studies are needed to assess its real incidence and identify possible risk factors.

Biophysical methods for the determination of antibody-antigen affinities

Binding specificities against virtually any antigen can be isolated from antibody libraries displayed on filamentous phage. The determination of antibody-antigen affinity constants and binding kinetics is an important part of antibody characterization, and may be predictive of antibody performance in biotechnological applications. This article, intended as a guideline for the scientist who isolates a novel antibody and wishes to characterize its binding properties, presents the authors' view on widely used methodologies for the quantitative determination of antibody-antigen interactions.

Phage antibodies with pan-species recognition of the oncofoetal angiogenesis marker fibronectin ED-B domain

Fibronectin (FN) exists in several polymorphic forms due to alternative splicing. The B-FN isoform (with ED-B domain inserted by splicing) is present in the stroma of foetal and neoplastic tissues and in adult and neoplastic blood vessels during angiogenesis but is undetectable in mature vessels. This isoform, therefore, represents a promising marker for angiogenesis, as already shown using the mouse monoclonal antibody (MAb) BC-1 directed against an epitope on human B-FN. However, this MAb does not directly recognise the human ED-B domain nor does it recognise B-FN of other species; therefore, it cannot be used as a marker of angiogenesis in animal models. In principle, antibodies directed against the human ED-B domain should provide pan-species markers for angiogenesis as the sequence of this domain is highly conserved in different species (and identical in humans and mice). As it has proved difficult to obtain such antibodies by hybridoma technology, we used phage display technology. Here, we describe the isolation of human antibody fragments against the human ED-B domain that bind to human, mouse and chicken B-FN. As shown by immunohistochemistry, the antibody fragments stain human neoplastic tissues and the human, mouse and chicken neovasculature.

Recombinant anti-human melanoma antibodies are versatile molecules

The low cost, high versatility, and reliable production of bacterially produced recombinant antibody fragments speeds up the development of tumor-targeting agents. High-quality recombinant anti-melanoma antibodies are much sought after in the scientific community. We cloned the murine antibody 225.28S, currently used in radioimmunoimaging of human melanoma lesions, in single-chain Fv configuration (scFv) for soluble expression in bacteria. The recombinant antibody fragment conserved the binding specificity of the parental antibody. In order to arm the scFv(225.28S) with biologically useful effector functions, we developed vectors for soluble expression of scFv(225.28S) in bacteria that allow both covalent and noncovalent chemical antibody modification at positions that do not interfere with antigen binding. An expression vector was developed that appends a cysteine residue at the C-terminal extremity of the recombinant antibody, thus allowing reaction with thiol-specific reagents, including 99mTc labeling, at a position that does not interfere with antigen binding. The scFv(225.28S) was also successfully expressed with a casein kinase II substrate tag that enables efficient and stable 32P labeling. For noncovalent antibody modification, we developed an expression vector that appends the human calmodulin gene at the C-terminal extremity of scFv(225.28S). The calmodulin domain is poorly immunogenic and can be targeted with chemically modified high-affinity calmodulin ligands. The recombinant anti-human melanoma antibodies described in this article should prove useful "building blocks" for the development of anti-melanoma diagnostic and therapeutic strategies.

Ultrasound-guided fine needle biopsy and laparoscopy in the study of pancreatic masses: report on 136 cases

The authors report their experience from 136 fine needle ultrasound (FN-US)-guided biopsies and laparoscopies. The pancreatic diseases considered by these methods were as follows: 9 cases of Pancreatitis, 11 cases of Pancreatic cysts, 5 cases of endocrine cancer, 109 cases of Exocrine cancer and 2 not conclusive cases. Diagnostic accuracy of FNB and laparoscopy was evaluated for each group and, in particular, for cancer patients. In the latter group, FNB helped to detect abdominal diffusion in 25 cases (33%) while laparoscopy, including laparoscopic washing, revealed a micro-diffusion in 31 cases (55%), the latter not shown previously by CT, RNM and US. The combination of these methods allows us to confirm the advanced stage of the majority of pancreatic cancers at onset. Furthermore, this seems to be a very reliable method to select resectable patients, thus avoiding useless, sometimes hazardous and expensive further investigation.

Alanine substitutions in calmodulin-binding peptides result in unexpected affinity enhancement

Calmodulin is a calcium-binding protein that regulates a wide range of enzymes. It is also one of the few examples of a small protein capable of binding to peptides with very high affinity, and is therefore an interesting candidate for biotechnological applications and a good model system for studying how proteins associate. We have synthesized a complete series of peptides derived from the recognition sequence of skeletal muscle myosin light-chain kinase, corresponding to single-point amino acid mutations to alanine. These peptides bind to calmodulin with a biphasic kinetic: a fast association step followed by a slow intramolecular isomerisation. We have measured the isomerisation rate (k(isom)) of these peptides for calmodulin by stopped-flow analysis, and their association and dissociation kinetic constants (k(on) and k(off)) by real-time interaction analysis using surface plasmon resonance detection. In addition, k(off) constants were measured by competition experiments using a high-sensitivity luminescence analyser and native polyacrylamide gels. We have observed that all the alanine-scanning peptides bound to calmodulin with better affinity than the wild-type. In one case, a Asn-->Ala substitution resulted in a 1000-fold improvement in affinity, owing to a slower off-rate. Our results indicate that naturally occurring calmodulin binders may have evolved to have high affinities, but far from the maximum. Our affinity data are in contrast with recently published predictions of interactions responsible for high-affinity calmodulin binding based on modelling and energy calculations.

Multipurpose high sensitivity luminescence analyzer (LUANA): use in gel electrophoresis

Many applications in molecular biology require the rapid and high-sensitivity detection of biological macromolecules. Here we describe a luminescence analyzer (LUANA), featuring xenon lamp-based illumination and a cooled CCD camera as detector. Luminescent samples (gels, membranes or microplates) are placed in a light-tight chamber, and computer software is used to control the camera and to display and analyze the images. LUANA can be used with a broad spectrum of excitation and emission wavelengths (200-1000 nm), allowing a choice of many fluorescent dyes and facilitating multicolor imaging. We show that LUANA is readily applicable to gel electrophoresis and highly sensitive; on gels we could detect < 100 fg of Cy5TM-labeled protein and 0.1 ng of plasmid DNA labeled with a fluorescent intercalator. We observed a linear response for sample concentrations differing by two orders of magnitude using a single acquisition time. This range could be further extended by using different acquisition times. We have also used LUANA in two-color imaging of DNA and for screening of antigen-antibody and peptide-protein complexes by gel bandshift.

Radioactive labeling of recombinant antibody fragments by phosphorylation using human casein kinase II and [gamma-32P]-ATP

A wide range of antibody fragments can be expressed in bacteria and detected immunochemically via peptide tags. Using specially designed tags, we have developed a strategy for radiolabeling antibody fragments secreted from bacteria. Tagged antibody fragments were secreted either into the bacterial periplasm or the culture medium. The tag was not subject to proteolysis either in the broth or in human plasma. After affinity purification the antibody fragments were phosphorylated with [gamma-32P]ATP and casein kinase II. The labeled fragments were used in a gel band-shift assay to measure antigen binding affinities. In contrast to non site-specific methods such as radioiodination, antibodies labeled with casein kinase II retain full immunoreactivity. Radioactively phosphorylated antibody fragments may have many other applications, including radioimmunoassays and radioimmunotherapy.

Efficient one-step direct labelling of recombinant antibodies with technetium-99m

High-affinity bacterially expressed antibody fragments can nowadays be cloned from established hybridomas or, more conveniently, isolated directly from antibody libraries displayed on filamentous phage. Such antibodies can be tagged with C-terminal peptide tags containing one cysteine residue, which represents a convenient functionalisation site for a number of applications, including technetium-99m labelling. Here we describe a simple one-step method for 99mTc labelling of cysteine-tagged recombinant antibodies with more than 50% radionuclide incorporation. The labelled antibodies displayed full retention of immuoreactivity and good stability.

Engineering recombinant antibodies for immunotherapy

Recombinant antibody fragments binding with high affinity to their target can be obtained either from hybridomas or directly from antibody libraries on filamentous phage. These fragments are devoid of any activity other than antigen binding, and have to be processed and functionalized in order to be suitable for clinical applications. This article presents the authors' view on the procedures and the features that are important for effective transformation of recombinant antibodies into useful immunotherapeutic agents. The topics presented include phage display methodologies, engineering of high-affinity binding, purification, and functionalization strategies of recombinant antibodies.

Calmodulin as a versatile tag for antibody fragments

Calmodulin is a highly acidic protein (net charge -24 at pH 8.0 in the absence of calcium) that binds to peptide and organic ligands with high affinity (Ka > 10(9) M-1) in a calcium-dependent manner. We have exploited these properties to develop calmodulin as a versatile tag for antibody fragments. Fusions of calmodulin with single chain Fv fragments (scFv) could be expressed by secretion from bacteria in good yield (5-15 mg/l in shaker flasks), and purified from periplasmic lysates or broth to homogeneity in a single step, either by binding to anion-exchange resin (DEAE-Sephadex), or to an organic ligand of calmodulin (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide-agarose). The antibody fusions could be detected by binding of fluorescently labeled peptide ligands, as illustrated by their use in confocal microscopy, fluorescent activated cell sorting and "band shift" gel electrophoresis. Moreover, the interaction between calmodulin and peptide ligands could provide a means of heterodimerization of proteins, as illustrated by the assembly of an antibody-calmodulin fusion with maltose binding protein tagged with a peptide ligand of calmodulin.