Management of Zygomatic Fractures in Young Patients: Technical Modifications for Aesthetic and Functional Results.

INTRODUCTION: The zygomaticomaxillary complex is very vulnerable to injury because of its intrinsically prominent convexity. There are 2 different surgical approaches for the therapy of these fractures: closed reduction and open reduction. In the open reduction 2 or 3 fixation points with related incisions are usually necessary in dislocated fractures: osteosynthesis must be performed starting from zygomaticofrontal suture when dislocated at this site, followed by zygomatic body fixation on the anterior sinus wall, anterior orbital floor margin fixation, and finally orbital floor reconstruction in case of eye globe dislocation with diplopia. AIM: This study evaluated the combination of the transconjunctival (TC) approach without canthotomy in association with the transoral maxillary approach and lateral rim skin incision (SI) without canthotomy for frontozygomatic dislocated fractures to achieve proper reduction and stabilization without any aesthetic decay in young patients. A less invasive and more aesthetic technique is shown for treating dislocated zygomaticomaxillary complex fractures with 2 or 3 fixation points and platelet-rich fibrin (PRF) use to promote tissue healing. MATERIALS AND METHODS: Ten patients (mean age: 32) were referred for dislocated zygomaticomaxillary complex fracture. Five patients were treated by TC approach without canthotomy in association with the transoral maxillary approach and, when needed, eyebrow SI without canthotomy for frontozygomatic dislocated fractures (group 1). Five more patients were treated by traditional subciliar incision at lower eyelid and vertical lateral incision at lateral margin of the orbit (group 2). Autologous PRF for orbital floor reconstruction was used. The follow-up period was 6 months long. Follow-up radiographs (TC) and photos were routinely used to evaluate the adequacy of reduction and lower eyelid right position or retraction. RESULTS: All cases were successful; there were no problems at surgery and postoperative time. During the 6-month follow-up, all 5 patients of group 1 showed satisfactory facial symmetry, no noticeable scarring, no ectropion or lower eyelid significant droop, and no functional impairment. Mean difference for lower eyelid droop between the 2 groups of patients was 1.4 mm at T1 and 1.2 mm at T2. DISCUSSION: Aesthetic result is a priority in the treatment planning of orbitozygomatic fractures because of the fundamental role of the eye and lid area in the aesthetic of the face. In our experience best aesthetic results were achieved through a latero cantal horizontal SI combined to a vertical periosteal incision at the frontozygomatic rim without canthotomy, thus performing a different double-layer incision. In the patients with large orbital floor dislocation, reconstructive titanium mesh was covered by autologous PRF membranes, which can improve the vascularization of the surgical site, by promoting neoangiogenesis. CONCLUSIONS: In young patients these techniques are indicated because of the need of better aesthetic results that can be achieved by preventing postoperative functional impairment with lower eyelid droop and unnatural aesthetic asymmetry of the 2 lower lids. This more conservative technique resulted in better aesthetic results, avoiding most common complications.

New Techniques in Relation to New Concepts of the Aesthetic of the Face: Technical Considerations and Aesthetic Evaluation.

Aesthetic of the face is greatly changed in relation to common standards of the past. Modern concepts of beauty from popular models of beautiful faces to actors show a biprotrusive asset with high tension for soft tissues. Facial symmetry has been proposed as a marker of developmental stability that may be important in human mate choice. Any deviation from perfect symmetry can be considered a reflection of imperfect development. The goal of maxillofacial surgery should be to give the best results for both aesthetic and functional aspects. Following these new concepts of aesthetic of the face, new surgical procedure by osteodistraction techniques will lead to a very natural final result by harmonizing the face. The aim of this study was to detect aesthetic results on 10 patients operated for skeletal discrepancies by maxillary distraction and jaw repositioning compared with other 10 patients operated by conventional techniques on a 5-point scale by Likert.

Distraction techniques for face and smile aesthetic preventing ageing decay.

Modern concepts in the world of beauty arise from popular models, beautiful faces of actors document a bi-protrusive asset with high tension for soft tissues. Facial symmetry has been proposed as a marker of development and stability that may be important in human mate choice. For various traits any deviation from perfect symmetry can be considered a reflection of imperfect development. Additionally, bi-protrusive profile is dependent on the hormonal level regardless of male or female sex. The goal of maxillofacial surgery is to provide best results both for aesthetic and functional aspects. Following these new concepts of aesthetic of the face, new surgical procedure by osteodistraction techniques will lead to a very natural result by harmonizing the face also preventing aesthetic decay in aging faces. Ten cases with a feedback on the aesthetic results using the fivepoint scale of Likert after orthognatic surgery performed following distraction new techniques in combination with ancillary surgical procedures. The aesthetic results in all patients were highly satisfactory. All the patients accepted the new aesthetic of the face avoiding elements of discrepancy and consequently medico-legal problems.

Hemangiomas of the maxillofacial area: Case Report, Classification and Treatment Planning.

Vascular lesions of the maxillofacial area are even more challenging than in other different body district, because of the high aesthetic and functional relevance of this area for the sense organs presence like eye, brain, tongue, ear and nose. For these reasons, we propose an accurate classification based on hemodynamic and histologic aspects usefulthat is for diagnostic and therapeutic planning. A female, 60 years old patient came to our observation showing a vascular lesion of the lower left lip, and complaining for aesthetical and functional impairment. To confirm the diagnosis of vascular malformation and to detect lesion flow rate or other possible localization, a Tc red blood cell scintigraphy was carried out. Result was a venous low flow lesion; hence, sclerotherapy by a 3% Polidocanol solution (Atossisclerol) followed by surgery was planned. The aim of this work was to propose a diagnostic and therapeutic scheme with an integration of ISSVA and a flow rate classifications for a three-step planning based on 1) the biological findings in an early age at the lesion discover with a pharmacological treatment; 2) Hemodynamic study of the lesions at growing age followed by sclerotherapy or embolization; 3) Imaging study of these lesions for patients candidate to surgery when after step 1 and step 2 diagnostic and therapeutic planning results were incompletely successful.

Three-dimensional domain swapping and supramolecular protein assembly: insights from the X-ray structure of a dimeric swapped variant of human pancreatic RNase.

The deletion of five residues in the loop connecting the N-terminal helix to the core of monomeric human pancreatic ribonuclease leads to the formation of an enzymatically active domain-swapped dimer (desHP). The crystal structure of desHP reveals the generation of an intriguing fibril-like aggregate of desHP molecules that extends along the c crystallographic axis. Dimers are formed by three-dimensional domain swapping. Tetramers are formed by the aggregation of swapped dimers with slightly different quaternary structures. The tetramers interact in such a way as to form an infinite rod-like structure that propagates throughout the crystal. The observed supramolecular assembly captured in the crystal predicts that desHP fibrils could form in solution; this has been confirmed by atomic force microscopy. These results provide new evidence that three-dimensional domain swapping can be a mechanism for the formation of elaborate large assemblies in which the protein, apart from the swapping, retains its original fold.

Ribonuclease/angiogenin inhibitor 1 regulates stress-induced subcellular localization of angiogenin to control growth and survival.

Angiogenin (ANG) promotes cell growth and survival. Under growth conditions, ANG undergoes nuclear translocation and accumulates in the nucleolus where it stimulates rRNA transcription. When cells are stressed, ANG mediates the production of tRNA-derived stress-induced small RNA (tiRNA), which reprograms protein translation into a survival mechanism. The ribonucleolytic activity of ANG is essential for both processes but how this activity is regulated is unknown. We report here that ribonuclease/angiogenin inhibitor 1 (RNH1) controls both the localization and activity of ANG. Under growth conditions, ANG is located in the nucleus and is not associated with RNH1 so that the ribonucleolytic activity is retained to ensure rRNA transcription. Cytoplasmic ANG is associated with and inhibited by RNH1 so that random cleavage of cellular RNA is prevented. Under stress conditions, ANG is localized to the cytoplasm and is concentrated in stress granules where it is not associated with RNH1 and thus remains enzymatically active for tiRNA production. By contrast, nuclear ANG is associated with RNH1 in stressed cells to ensure that the enzymatic activity is inhibited and no unnecessary rRNA is produced to save anabolic energy. Knockdown of RNH1 abolished stress-induced relocalization of ANG and decreased cell growth and survival.

A novel interdomain interface in crystallins: structural characterization of the ßγ-crystallin from Geodia cydonium at 0.99 Å resolution.

The ßγ-crystallin superfamily includes highly diverse proteins belonging to all of the kingdoms of life. Based on structural topology, these proteins are considered to be evolutionarily related to the long-lived ßγ-crystallins that constitute the vertebrate eye lens. This study reports the crystallographic structure at 0.99 Å resolution of the two-domain ßγ-crystallin (geodin) from the sponge Geodia cydonium. This is the most ancient member of the ßγ-crystallin superfamily in metazoans. The X-ray structure shows that the geodin domains adopt the typical ßγ-crystallin fold with a paired Greek-key motif, thus confirming the hypothesis that the crystallin-type scaffold used in the evolution of bacteria and moulds was recruited very early in metazoans. As a significant new structural feature, the sponge protein possesses a unique interdomain interface made up by pairing between the second motif of the first domain and the first motif of the second domain. The atomic resolution also allowed a detailed analysis of the calcium-binding site of the protein.

Mechanisms of cardiotoxicity associated with ErbB2 inhibitors.

The ErbB2 receptor is a proto-oncogene associated with a poor prognosis in breast cancer. Herceptin, the only humanized anti-ErbB2 antibody currently in clinical use, has proven to be an essential tool in the immunotherapy of breast carcinoma, but induces cardiotoxicity. ErbB2 is involved in the growth and survival pathway of adult cardiomyocytes; however, its levels in the adult heart are much lower than those found in breast cancer cells, the intended targets of anti-ErbB2 antibodies. Furthermore, clinical trials have shown relatively low cardiotoxicity for Lapatinib, a dual kinase inhibitor of EGFR and ErbB2, and Pertuzumab, a new anti-ErbB2 monoclonal antibody currently in clinical trials, which recognizes an epitope distant from that of Herceptin. A novel human antitumor compact anti-ErbB2 antibody, Erb-hcAb, selectively cytotoxic for ErbB2-positive cancer cells in vitro and vivo, recognizes an epitope different from that of Herceptin, and does not show cardiotoxic effects both in vitro on rat and human cardiomyocytes and in vivo on a mouse model. We investigated the molecular basis of the different cardiotoxic effects among the ErbB2 inhibitors by testing their effects on the formation of the Neuregulin 1ß (NRG-1)/ErbB2/ErbB4 complex and on the activation of its downstream signaling. We report herein that Erb-hcAb at difference with Herceptin, 2C4 (Pertuzumab) and Lapatinib, does not affect the ErbB2-ErbB4 signaling pathway activated by NRG-1 in cardiac cells. These findings may have important implications for the mechanism and treatment of anti-ErbB2-induced cardiotoxicity.

Effects of a human compact anti-ErbB2 antibody on prostate cancer.

Prostate cancer is the most commonly diagnosed malignancy in men in developed countries. ErbB2, a tyrosine kinase receptor overexpressed in many human cancer types, contributes to prostate cancer progression by activating the androgen receptor in a steroid poor environment, thus promoting androgen-independent cell growth. The consequent development of hormone refractory tumors is a major obstacle in prostate cancer therapy. The inhibition of ErbB2 signal transduction pathways by the use of human antibodies could be a valuable alternative strategy for cancer therapy. We performed a comparative analysis in vitro and in vivo of the antitumor effects of three different antibodies targeting different epitopes of ErbB2: Herceptin (trastuzumab), 2C4 (pertuzumab) and Erb-hcAb (human anti-ErbB2-compact antibody), a novel fully human compact antibody produced in our laboratory. Herein, we demonstrate that the growth of both androgen-dependent and independent prostate cancer cells was efficiently inhibited by Erb-hcAb. The antitumor effects induced by Erb-hcAb on some cell lines were more potent than those observed for either Herceptin or 2C4. Thus, Erb-hcAb could be a promising candidate in the immunotherapy of prostate cancer for which no obvious treatment has been reported so far.

Comparison of preclinical cardiotoxic effects of different ErbB2 inhibitors.

Two novel human antitumor immunoconjugates, made up of a human anti-ErbB2 scFv, Erbicin, fused with either a human RNase or the Fc region of a human IgG1, are selectively cytotoxic for ErbB2-positive cancer cells in vitro and in vivo. The Erbicin-derived immunoagents (EDIA) target an epitope different from that of trastuzumab, the only humanized antibody currently prescribed for treatment of ErbB2-positive breast cancer (BC). As Trastuzumab has shown cardiotoxic effects, in this study, we evaluated if any side effects were exerted also by EDIA, used as single agents or in combination with anthracyclines. Furthermore, we compared the in vitro and in vivo cardiotoxic effects of EDIA with those of the other available anti-ErbB2 drugs: Trastuzumab, 2C4 (Pertuzumab), and Lapatinib. In this article, we show that EDIA, in contrast with Trastuzumab, 2C4, and Lapatinib, have no toxic effects on human fetal cardiomyocytes in vitro, and do not induce additive toxicity when combined with doxorubicin. Furthermore, EDIA do not impair cardiac function in vivo in mice, as evaluated by Color Doppler echocardiography, whereas Trastuzumab significantly reduces radial strain (RS) at day 2 and fractional shortening (FS) at day 7 of treatment in a fashion similar to doxorubicin. Also 2C4 and Lapatinib significantly reduce RS after only 2 days of treatment, even though they showed cardiotoxic effects less pronounced than those of Trastuzumab. These results strongly indicate that RS could become a reliable marker to detect early cardiac dysfunction and that EDIA could fulfill the therapeutic need of patients ineligible to Trastuzumab treatment because of cardiac dysfunction.

Denatured bactericidal proteins: active per se, or reservoirs of active peptides?

According to the structure-to-function paradigm proteins fold into a 3D structure for exerting their functions. Intrinsically destructured proteins with important biological functions have been identified and studied, but they assume a structure when interacting in the cell with their partners. There are instead bactericidal proteins, endowed also with other diverse activities (glycoside hydrolases, RNases, a defensin), which are lost when the proteins are denatured or inactivated, whereas the bactericidal activity is surprisingly conserved. The hypothesis is advanced that these proteins are not bactericidal per se, but because they store in their amino acid sequences peptide segments that display bactericidal activity when cut out as free peptides from the proteins. These bactericidal proteins would thus be merely containers of bactericidal peptides.

The ribonuclease/angiogenin inhibitor is also present in mitochondria and nuclei.

The data presented here show for the first time that the protein known as "ribonuclease (RNase) inhibitor" (RI or RNH1) is present not only in the cell cytosol, but also in mitochondria, the central organelles in cell redox homeostasis. This finding directly correlates with the reported ability of RI to protect the cell from oxidative stress, with its sensitivity to oxidation and reactivity as a reactive oxygen species scavenger. While this study was carried out we also surprisingly discovered the presence of RI in the cell nucleus. We deem that these data open new views in the investigation on the cellular role(s) of the RI.

A novel ErbB2 epitope targeted by human antitumor immunoagents.

Two novel human antitumor immunoconjugates, engineered by fusion of a single-chain antibody fragment against human ErbB2 receptor, termed Erbicin, with either a human RNase or the Fc region of a human IgG(1) , are selectively cytotoxic for ErbB2-positive cancer cells in vitro and in vivo. These Erbicin-derived immunoagents (EDIAs) do not show the most negative properties of Herceptin, the only humanized mAb against ErbB2 used in the therapy of breast carcinoma: cardiotoxicity and the inability to act on resistant tumors. These differences are probably attributable to the different ErbB2 epitopes recognized by EDIAs and Herceptin, respectively, as we have previously reported that they induce different signaling mechanisms that control tumor and cardiac cell viability. Thus, to accurately identify the novel epitope recognized by EDIAs, three independent and complementary methodologies were used. They gave coherent results, which are reported here: EDIAs bind to a different ErbB2 epitope than Herceptin and the other human/humanized antibodies against ErbB2 reported so far. The epitope has been successfully located in region 122-195 of extracellular domain I. These findings could lead to the identification of novel epitopes on ErbB2 that could be used as potential therapeutic targets to mitigate anti-ErbB2-associated cardiotoxicity and eventually overcome resistance.

Structure-cytotoxicity relationships in bovine seminal ribonuclease: new insights from heat and chemical denaturation studies on variants.

Bovine seminal ribonuclease (BS-RNase), a homodimeric protein displaying selective cytotoxicity towards tumor cells, is isolated as a mixture of two isoforms, a dimeric form in which the chains swap their N-termini, and an unswapped dimer. In the cytosolic reducing environment, the dimeric form in which the chains swap their N-termini is converted into a noncovalent dimer (termed NCD), in which the monomers remain intertwined through their N-terminal ends. The quaternary structure renders the reduced protein resistant to the ribonuclease inhibitor, a protein that binds most ribonucleases with very high affinity. On the other hand, upon selective reduction, the unswapped dimer is converted in two monomers, which are readily bound and inactivated by the ribonuclease inhibitor. On the basis of these considerations, it has been proposed that the cytotoxic activity of BS-RNase relies on the 3D structure and stability of its NCD derivative. Here, we report a comparison of the thermodynamic and chemical stability of the NCD form of BS-RNase with that of the monomeric derivative, together with an investigation of the thermal dissociation mechanism revealing the presence of a dimeric intermediate. In addition, we report that the replacement of of Arg80 by Ser significantly decreases the cytotoxic activity of BS-RNase and the stability of the NCD form with respect to the parent protein, but does not affect the ribonucleolytic activity or the dissociation mechanism. The data show the importance of Arg80 for the cytotoxicity of BS-RNase, and also support the hypothesis that the reduced derivative of BS-RNase is responsible for its cytotoxic activity.

A new RNase sheds light on the RNase/angiogenin subfamily from zebrafish.

Recently, extracellular RNases of the RNase A superfamily, with the characteristic CKxxNTF sequence signature, have been identified in fish. This has led to the recognition that these RNases are present in the whole vertebrate subphylum. In fact, they comprise the only enzyme family unique to vertebrates. Four RNases from zebrafish (Danio rerio) have been previously reported and have a very low RNase activity; some of these are endowed, like human angiogenin, with powerful angiogenic and bactericidal activities. In the present paper, we report the three-dimensional structure, the thermodynamic behaviour and the biological properties of a novel zebrafish RNase, ZF-RNase-5. The investigation of its structural and functional properties, extended to all other subfamily members, provides an inclusive description of the whole zebrafish RNase subfamily.

The bactericidal action on Escherichia coli of ZF-RNase-3 is triggered by the suicidal action of the bacterium OmpT protease.

ZF-RNase-3 is one of the RNases from zebrafish (Danio rerio) with special (i.e. noncatalytic) properties. These include angiogenic and bactericidal activities. Given the interest of fish RNases as host-defense effectors, we studied the mechanism of the bactericidal action of ZF-RNase-3 on Escherichia coli as a model Gram-negative bacterium. The results obtained indicate that the bactericidal activity of ZF-RNase-3 is not lost when its catalytic RNase activity is obliterated. On the other hand, fully denatured ZF-RNase-3 conserves its bactericidal activity. When ZF-RNase-3 is added to E. coli cultures, it is cleaved at a specific Arg-Arg peptide bond, thus engendering two peptide fragments. The larger fragment (residues 31-124), produced by proteolysis and reduction of a disulfide, is recognized as the actual bactericidal agent. The protease responsible for the proteolytic attack has been identified with OmpT, an outer membrane E. coli omptin protease. However, the most remarkable result obtained in the present study is the finding that the microbicidal action of ZF-RNase-3 can be achieved only with the suicidal cooperation of the bacterium itself.

IL-6 Induction by TNFα and IL-1ß in an Osteoblast-Like Cell Line.

Stress cytokines tumor necrosis factor α, interleukin-1 ß and interleukin-6 modulate the activity of a variety of cell types including osteoblasts, and are involved in the pathogenesis of several rheumatic diseases associated with systemic bone loss. We have studied the expression of interleukin-6 induced by interleukin-1 ß and tumor necrosis factor α in the osteoblast-like cell line MG-63, derived from a human osteosarcoma. We have observed marked differences in the regulation of interleukin-6 gene expression by tumor necrosis factor α or interleukin-1 ß, at the level of mRNA steady state and stability and cytokine secretion. In addition, N-acetyl cysteine, a scavenger of reactive oxygen species, inhibits activation of NF-κB and induction of interleukin-6 by tumor necrosis factor α, being ineffective on interleukin-1 ß activity. These data illustrate the action of stress cytokines on a cell line widely used in in vitro studies as a reliable model of osteoblast response to cytokines involved in bone resorbing diseases, an important issue for developing new strategies for treatments of bone diseases.

Characterization of the angiogenic activity of zebrafish ribonucleases.

Ribonucleases identified from zebrafish possess angiogenic and bactericidal activities. Zebrafish RNases have three intramolecular disulfide bonds, a characteristic structural feature of angiogenin, different from the typical four disulfide bonds of the other members of the RNase A superfamily. They also have a higher degree of sequence homology to angiogenin than to RNase A. It has been proposed that all RNases evolved from these angiogenin-like progenitors. In the present study, we characterize, in detail, the function of zebrafish RNases in various steps in the process of angiogenesis. We report that zebrafish RNase-1, -2 and -3 bind to the cell surface specifically and are able to compete with human angiogenin. Similar to human angiogenin, all three zebrafish RNases are able to induce phosphorylation of extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase. They also undergo nuclear translocation, accumulate in the nucleolus and stimulate rRNA transcription. However, zebrafish RNase-3 is defective in cleaving rRNA precursor, even though it has been reported to have an open active site and has higher enzymatic activity toward more classic RNase substrates such as yeast tRNA and synthetic oligonucleotides. Taken together with the findings that zebrafish RNase-3 is less angiogenic than zebrafish RNase-1 and -2 as well as human angiogenin, these results suggest that zebrafish RNase-1 is the ortholog of human angiogenin and that the ribonucleolytic activity of zebrafish RNases toward the rRNA precursor substrate is functionally important for their angiogenic activity.

Cardiotoxic effects, or lack thereof, of anti-ErbB2 immunoagents.

This study investigated potential cardiotoxicity as exerted by Erbicin-derived-immunoagents (EDIAs), novel human anti-ErbB2 immunoagents engineered by fusion of a human anti-ErbB2 scFv, Erbicin, with either a human RNase or the Fc region of a human IgG1. EDIAs are strongly cytotoxic on ErbB2-positive cells in vitro and in vivo and bind to an epitope different from that of Herceptin, a humanized anti-ErbB2 mAb effective in the therapy of breast carcinoma, but cardiotoxic in a high percentage of cases. Toxicity and apoptosis were tested in vitro by 3-(4,5-dimethyl-2-thizolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), DNA fragmentation, and immunoblotting analyses. Echocardiography was measured in mice after treatment with each immunoagent. Cardiac fibrosis and detection of apoptosis were examined by Sirius red staining of collagen and TUNEL assay, respectively. EDIAs were found in vitro to have no adverse effects on cardiac cells for which Herceptin is severely toxic. In vivo studies on a mouse model showed that the EDIAs did not alter cardiac function, whereas Herceptin and doxorubicin, used as positive controls, significantly reduced the fractional shortening parameter. Cardiac fibrosis and apoptosis were not significantly affected in mice treated with EDIAs. Thus, EDIAs could fulfill the therapeutic need of patients ineligible for Herceptin treatment due to cardiac dysfunction.

Human anti-ErbB2 immunoagents--immunoRNases and compact antibodies.

Immunotherapy, based on mAbs specifically directed against cancer cells, is considered a precious strategy in the fight against cancer because of its selectivity and lack of multidrug resistant effects. However, there are obstacles to the complete success of current immunotherapy such as immune responses to nonhuman or even humanized antibodies and the large size of the antibodies, which hinders their diffusion into bulky tumors. Fully human, small immunoagents, capable of inhibiting tumor growth may overcome these problems and provide safe, highly selective and effective antitumor drugs. An attractive target for immunotherapy is ErbB2, a transmembrane tyrosine kinase receptor, overexpressed on tumor cells of different origin, with a key role in the development of malignancy. An anti-ErbB2 humanized monoclonal (Herceptin) is currently used with success for breast cancer therapy; however, it can engender cardiotoxicity and a high proportion of breast cancer patients are resistant to Herceptin treatment. Anti-ErbB2 immunoagents of human origin, with potentially no or very low immunogenicity have been engineered to assemble 'compact', i.e. reduced size, antibodies, one consisting of a human single-chain antibody fragment (scFv) fused to a human RNase to construct an immunoRNase and the other made up of two human scFv molecules fused to the Fc region of a human IgG1. By choosing a human antibody fragment as the immune moiety and a human RNase as the effector moiety, an immunoRNase would be both nonimmunogenic and nontoxic, as it becomes toxic only when the scFv promotes its internalization by target cells. The alternative strategy of compact antibodies was aimed at producing therapeutic agents with an increased half-life, prolonged tumor retention and the ability to recruit host effector functions. Moreover, the bivalency of compact antibodies can be exploited to construct bispecific antibodies, as well as for other therapeutic applications.