Structural formation of multifunctional NiMoO4 nanorods for thermoelectric applications.

We report on the synthesis and characterization of NiMoO4 (NMO) nanorods via the hydrothermal method. The High-Resolution Scanning Electron Microscopy (HRSEM) image reveals the nanorod morphology of NMO. The formation of mixed phase α,ß-NMO is confirmed and the crystallite size of the nanorods is measured to be 40 nm from the XRD data. The structural formation of NMO is confirmed by Raman, FTIR, and XPS. The content of Ni, Mo and O was identified from XPS. NMO is optically active in the visible region with the band gap of 3.085 eV. The presence of four oxygen anions in the chemical formula gives the maximum electrical resistivity of 102 Ω m at 313 K and the material exhibits n-type semiconducting nature which is observed through Seebeck measurement and the Hall coefficient. The n-type semiconducting properties are observed due to the material being richer in Mo than Ni. The attained maximum Seebeck value of -159.723 µV K-1 at 513 K is comparable with that of other good thermoelectric materials at low temperatures. A decrease in the value of thermal conductivity was observed as a function of increasing temperature; NMO has the minimum thermal conductivity of 3.851 W m-1 K-1 at 513 K.

Stroke mimic: Perfusion magnetic resonance imaging of a patient with ictal paralysis.

We present an uncommon case of clinically diagnosed window period stroke subsequently recognised on diffusion - perfusion MRI as ictal paralysis due to focal inhibitory seizures or negative motor seizures. This case highlights the importance of MRI with perfusion imaging in establishing the diagnosis of stroke mimics and avoiding unnecessary thrombolysis.

The antibiotic rifampicin is a nonsteroidal ligand and activator of the human glucocorticoid receptor.

The glucocorticoid receptor (GR) belongs to a superfamily of ligand-regulated nuclear steroid hormone receptors. The steps in the signal transduction pathway leading to the biological effects of glucocorticoids (GCs) include sequentially binding of the steroid to the GR ligand binding domain (LBD), receptor transformation, nuclear translocation and either positive or negative gene transactivation. Rifampicin (RIF) is a macrocyclic antibiotic used as an antituberculosis agents. As the incidence of tuberculosis has been increasing, in part because of the AIDS epidemic, a growing number of patients are being exposed to the adverse effects of this antibiotic. Indeed, this compound, as are the GCs, is often implicated in noxious drug interactions, because of its strong ability to induce drug-metabolizing enzymes. Moreover, in humans, RIF, as are the GCs, has been described as a potential immunodepressor, associated notably with the reduction of mitogenic responsiveness of human peripheral blood lymphocytes. Here, we report that RIF activates the human glucocorticoid receptor (hGR). Transient expression of wild-type, deleted or mutated GRs; sucrose density gradient sedimentation; and the BIAcore technique strongly suggest that RIF binds to the receptor with the physiological consequence that this antibiotic acts as an immunodepressor. Given the wide use of RIF in the treatment of coinfection of tuberculosis and HIV, this report is highly relevant to current medical practice.

[Movember health care initiative 2019: prostate cancer screening at the University Hospital Frankfurt]. / Urologische Prostatakrebsvorsorge im Rahmen der Movember-Gesundheitsinitiative 2019 am Universitätsklinikum Frankfurt.

BACKGROUND: Men die earlier than women in Germany. Men also have impaired access to cancer screening compared to women. OBJECTIVES: Our Movember campaign 2019 at University Hospital Frankfurt (UKF) aimed at improving health care awareness in the context of prostate cancer checkup. MATERIALS AND METHODS: In November 2019, every male employee of the UKF with a minimum age of 45 yrs (or 40 yrs with a first degree relative with prostate cancer) was offered a free prostate cancer checkup. This checkup contained digital rectal examination (DRE), transrectal ultrasound and PSA (prostata-specific antigen) testing. RESULTS: Overall, 121/840 employees (14.4%) participated in the Movember campaign. A first degree relative with prostate cancer was reported in overall by 14% of the participants (n = 17). At least one prior prostate cancer check up had 33%. A total of 2.5% (n = 3) had one prior negative prostate biopsy. Median age was 54 yrs (interquartile range 50-58). Median PSA level was 0.9 ng/ml and median free-PSA 0.3 ng/ml. A suspicious DRE was found in 5% (n = 6). After stratification according to age (≤ 50 yrs vs. > 50 yrs), participants over 50 yrs had a significantly higher PSA level (1.0 ng/ml vs. 0.7 ng/ml, p < 0.01) and had more frequently at least one prior prostate cancer checkup in the past (42.0 vs. 12.1%, p < 0.01). All suspicious DREs were in the cohort > 50 yrs. Overall, 32.2% (n = 39) had at least a suspicious checkup. A total of 3.3% (n = 4) had suspicious PSA levels. 17.4% (n = 21) of the participants had a suspicious PSA ratio (< 20%) only. During follow-up, 6 prostate biopsies were performed, with the detection of one case of intermediate-risk prostate cancer (Gleason 3 + 4, pT3a, pPn1, pNx, R0). CONCLUSION: Overall, 121 employees participated in our Movember Prostate cancer checkup campaign with measurement of the PSA level. Suspicious results were recorded in 32.2%. One employee was diagnosed and successfully treated with an intermediate-risk prostate cancer.

[Awareness of clinical relevance of malignant testicular cancer among university students : The value of ​prevention campaigns]. / Das Bewusstsein bezüglich der klinischen Relevanz von bösartigen Hodentumoren unter Studierenden : Der Stellenwert von Aufklärungskampagnen.

BACKGROUND: Early detection of localized testicular cancer is associated with a significantly better prognosis compared to advanced tumor stages. Testicular cancer prevention campaigns like "Hodencheck.de" launched by the German Society of Urology or the international campaign "Movember Foundation" want to inform and raise awareness about testicular cancer and other male cancers. This study aimed to evaluate to which extent public prevention campaigns may influence the behavior of young men and women in Germany. OBJECTIVES: Questionnaires were used to ask students at the University of Frankfurt, Germany, whether they are familiar with the currently most widespread testicular cancer prevention campaigns and whether testicular examinations for cancer screening were performed by themselves, a partner or a physician. RESULTS: Only a minority of the students were aware of the testicular cancer prevention campaigns "Hodencheck.de" and/or "Movember Foundation"; 79.9% of the male and 83.6% of female students had not heard of the two mentioned prevention campaigns. Significantly more male (35.2%) compared to female students (28.9%) knew that testicular cancer is the most common cancer in young men. Of the men, 48.9% had already palpated their testicles, while only 12.4% of the women had already palpated the partner's testicles for cancer screening. Students knowing about the testicular cancer prevention campaigns performed significantly more testicular examinations for screening purposes. CONCLUSIONS: Our study demonstrates that current testicular cancer prevention campaigns are little known amongst German university students. However, the knowledge of testicular cancer prevention campaigns resulted in an increased awareness and an increased willingness for testicular (self-) examinations.

Crystal structure determination of two pyridine derivatives: 4-[(E)-2-(4-meth-oxy-phen-yl)ethen-yl]-1-methyl-pyridin-1-ium hexa-fluoro-λ6-phosphane and 4-{(E)-2-[4-(di-methyl-amino)-phen-yl]ethen-yl}-1-phenyl-1λ5-pyridin-1-ylium hexa-fluoro-λ6-phosphane.

The title mol-ecular salts, C16H16NO+·PF6 -, (I), and C21H21N2 +·PF6 -, (II), are pyridine derivatives. In compound (I), the cation comprises a methyl N-substituted pyridine ring and a meth-oxy-substituted benzene ring connected by a C=C double bond. The F atoms of the PF6 - anion are disordered over two sets of sites with refined occupancy factors of 0.614 (7):0.386 (7). In compound (II), the cation comprises a pyridine ring attached to unsubstituted phenyl ring and a di-methyl-aniline ring, which are connected by a C=C double bond. The anion is PF6 -. In both salts, the cation adopts an E configuration with respect to the C=C bond. The pyridine ring makes a dihedral angle of 9.86 (12)° with the meth-oxy-substituted benzene ring in compound (I) and 11.2 (3)° with the di-methyl-amine-substituted benzene ring in compound (II). In compound (I), the crystal packing is stabilized by weak C-H⋯F inter-molecular inter-actions which result in R 4 3(14) ring motifs, forming mol-ecular sheets running parallel to (03). These are further stabilized by weak P-F⋯π interactions. In compound (II), the crystal packing is stabilized by C-H⋯F inter-actions, which result in R 6 6(40) ring motifs, forming mol-ecular sheets running parallel to (101) and these are further connected by π-π inter-actions.

Curcumin combined with exposure to visible light blocks bladder cancer cell adhesion and migration by an integrin dependent mechanism.

OBJECTIVE: Although the natural compound curcumin exerts antitumor properties in vitro, its clinical application is hampered due to rapid metabolism. Light exposure following curcumin application has been demonstrated to improve curcumin's bioavailability. Therefore, this investigation was directed towards evaluating whether light exposure in addition to curcumin application enhances curcumin's efficacy against bladder cancer cell adhesion and migration. MATERIALS AND METHODS: RT112, UMUC3, and TCCSUP cells were incubated with low curcumin concentrations (0.1-0.4 µg/ml) and then exposed to 1.65 J/cm2 visible light for 5 min. Controls remained untreated or were treated with curcumin or light alone. Cell adhesion to Human umbilical vein endothelial cells (HUVECs), to immobilized collagen or fibronectin and chemotactic behavior, integrin α and ß receptor expression with functional relevance, as well as focal adhesion kinase (total and phosphorylated FAK) were evaluated. RESULTS: Curcumin plus light, but neither curcumin nor light alone, significantly altered tumor cell adhesion and suppressed chemotaxis. Integrin α and ß subtypes were dissimilarly modified, depending on the cell line. Suppression of pFAK was noted in RT112 and UMUC3, but not in TCCSUP cells. The integrins α3, α5, and ß1 were involved in curcumin's regulation of adhesion and migration. Blocking studies revealed α3, α5, and ß1 to be associated with TCCSUP adhesion and migration, whereas α5 and ß1, but not α3 contributed to UMUC3 adhesion and migration. Integrin α5 and ß1 controlled RT112 chemotaxis as well, but only α5 was involved in the RT112 adhesion process. CONCLUSIONS: Combining curcumin with light exposure enhances curcumin's anti-tumor potential.

[Prostate MRI spectroscopy]. / Spectroscopie par résonance magnétique de la prostate.

MRI spectroscopy is a non invasive method for detecting active metabolites used as markers. Chorine and citrate are used for analyzing prostate cancer. MRI spectroscopy combines morphologic imaging and metabolic cartography. This combination allows a new approach for the diagnosis of prostate cancer in patients with negative biopsy and high Levels of PSA. With MRI spectroscopy the Local staging of prostate cancer has a better accuracy than with MRI alone. It can also be used for the diagnosis of residual disease and recurrence in patients treated with conservative therapy.

Interactions of the human, rat, Saccharomyces cerevisiae and Escherichia coli 3-methyladenine-DNA glycosylases with DNA containing dIMP residues.

In DNA, the deamination of dAMP generates 2'-deoxy-inosine 5'-monophosphate (dIMP). Hypoxanthine (HX) residues are mutagenic since they give rise to A.T-->G.C transition. They are excised, although with different efficiencies, by an activity of the 3-methyl-adenine (3-meAde)-DNA glycosylases from Escherichia coli (AlkA protein), human cells (ANPG protein), rat cells (APDG protein) and yeast (MAG protein). Comparison of the kinetic constants for the excision of HX residues by the four enzymes shows that the E.coli and yeast enzymes are quite inefficient, whereas for the ANPG and the APDG proteins they repair the HX residues with an efficiency comparable to that of alkylated bases, which are believed to be the primary substrates of these DNA glycosylases. Since the use of various substrates to monitor the activity of HX-DNA glycosylases has generated conflicting results, the efficacy of the four 3-meAde-DNA glycosylases of different origin was compared using three different substrates. Moreover, using oligo-nucleotides containing a single dIMP residue, we investigated a putative sequence specificity of the enzymes involving the bases next to the HX residue. We found up to 2-5-fold difference in the rates of HX excision between the various sequences of the oligonucleotides studied. When the dIMP residue was placed opposite to each of the four bases, a preferential recognition of dI:T over dI:dG, dI:dC and dI:dA mismatches was observed for both human (ANPG) and E.coli (AlkA) proteins. At variance, the yeast MAG protein removed more efficiently HX from a dI:dG over dI:dC, dI:T and dI:dA mismatches.

Cytokine targeting in tumors using a bispecific antibody directed against carcinoembryonic antigen and tumor necrosis factor alpha.

The use of tumor necrosis factor alpha (TNFalpha) in cancer therapy is limited by its short circulatory half-life and its severe systemic side effects. To overcome these limitations, we evaluated the capability of a bispecific antibody (BAb) directed against carcinoembryonic antigen (CEA) and human TNFalpha to target this cytokine in tumors. A BAb was constructed by coupling the Fab' fragments from an anti-CEA monoclonal antibody (MAb) to the Fab' fragments from an anti-TNFalpha MAb via a stable thioether linkage. The double specificity of the BAb for CEA and TNFalpha was demonstrated using a BIAcoreTM two-step analysis. The affinity constants of the BAb for CEA immobilized on a sensor chip and for soluble TNFalpha added to the CEA-BAb complex were as high as those of the parental MAbs (1.7 x 10(9) M-1 and 6.6 x 10(8) M-1, respectively). The radiolabeled 125I-labeled BAb retained high immunoreactivity with both CEA and TNFalpha immobilized on a solid phase. In nude mice xenografted with the human colorectal carcinoma T380, the 125I-labeled BAb showed a tumor localization and biodistribution comparable to that of 131I-labeled anti-CEA parental F(ab')2 with 25-30% of the injected dose (ID)/g tumor at 24 h and 20% ID/g tumor at 48 h. To target TNFalpha to the tumor, a two-step i.v. injection protocol was used first, in which a variable dose of 125I-labeled BAb was injected, followed 24 or 48 h later by a constant dose of 131I-labeled TNFalpha (1 microg). Mice pretreated with 3 microg of BAb and sacrificed 2, 4, 6, or 8 h after the injection of TNFalpha showed a 1.5- to 2-fold increased concentration of 131I-labeled TNFalpha in the tumor as compared to control mice, which received TNFalpha alone. With a higher dose of BAb (25 microg), mice showed a better targeting of TNFalpha with a 3.2-fold increased concentration of 131I-labeled TNFalpha in the tumor: 9.3% versus 2.9% ID/g in control mice 6 h after TNFa injection. In a one-step injection protocol using a premixed BAb-TNFalpha preparation, similar results were obtained 6 h postinjection (3.5-fold increased TNFalpha tumor concentration). A longer retention time of TNFalpha was observed leading to an 8.1-fold increased concentration of TNFalpha in the tumor 14 h postinjection (4.4 versus 0.5% ID/g tumor for BAb-treated and control mice, respectively). These results show that our BAb is able, first, to localize in a human colon carcinoma and, there, to immunoabsorb the i.v.-injected TNFalpha, leading to its increased concentration at the tumor site.

Characterization of a new intrabody directed against the N-terminal region of human p53.

Genes encoding the rearranged immunoglobulin heavy and light chain variable regions of DO-1, a monoclonal antibody directed against human p53, have been used to construct a single-chain antibody. DO-1 recognizes an N-terminal epitope in the region involved in the transactivation function of p53 and the binding of Mdm2. The DO-1 single chain scFv expressed in the periplasm of E. coli or at the surface of the filamentous phage M13 retained the immunological specificity and affinity of the full length antibody. Furthermore, the DO-1 recombinant antibody was able to inhibit the in vitro binding of Hdm2, and was shown to be a powerful protecting agent of p53's DNA binding activity at 37 degrees C. The DO-1 single-chain antibody has been used to construct single-chain intracellular antibodies (intrabodies) for expression in the cytoplasm and the nucleus of mammalian cells. These anti-p53 intrabodies were additionally modified by addition of a Ckappa domain to increase cytoplasmic and nuclear stability. Here we show that expression of the DO-1 single-chain antibody in the H1299 cell line results in an inhibition of p53's transactivation function. The DO-1 intrabody is a useful tool to study those functions of p53 driven by the N-terminal region of the protein.

Extracellular ATP increases cytosolic free calcium in thymocytes and initiates the blastogenesis of the phorbol 12-myristate 13-acetate-treated medullary population.

Exogeneous nucleotides or nucleosides may influence lymphocyte functions such as proliferation and cytotoxicity. We report that ATP, and to a lesser extent ADP, at concentrations as low as 0.3 mM, are highly mitogenic for medullary mature thymocytes, when added in combination with phorbol myristate acetate (PMA), which is only weakly mitogenic by itself. Under the same conditions, the other nucleotides (AMP; GTP, ITP, 2'd-deoxyATP), the non-hydrolysable ATP analogs (p[NH]ppA, pp[CH2]pA) and adenosine are unable to trigger thymocyte blastogenesis. p[NH]ppA, a potent inhibitor of ATP hydrolysis, potentiates the ATP mitogenic effect. In contrast, T-cell-enriched splenocytes do not proliferate in response to ATP + PMA. These data and measurements of interleukin 2 synthesis suggest that ATP may efficiently deliver in thymocytes the calcium signal necessary for the initiation of blastogenesis (in medullary cells). Indeed, among all nucleotides tested, only ATP or ADP were able to increase the intracellular free calcium level in thymocytes, but not in splenocytes. Our results led us to suggest that thymocytes express on their surface receptors specific for ATP, which might be P2 type nucleotide receptors and could be involved in the lymphocyte response through the regulation of intracellular free calcium levels.

Studies of (Na+ + K+)-sensitive ATPase activity in pig lymphocytes. Effects of concanavalin A.

(Na+ + K+)-ATPase activity is demonstrated in plasma membranes from pig mesenteric lymph nodes. After dodecyl sulfate treatment plasma membranes have an 18-fold higher (Na+ + K+)-ATPase activity, while their ouabain-insensitive Mg2+-ATPase is markedly lowered. A solubilized (Na+ +K+)-ATPase fraction, obtained by Lubrol WX treatment of the membranes, has very high specific activity (21 mumol Pi/h per mg protein). Concanavalin A has no effect on these partially purified (Na+ + K+)-ATPase, while inhibits (40%) this activity in less purified fractions which still contain Mg2+-ATPase activity.

Alamethicin or detergent permeabilization of the cell membrane as a tool for adenylate cyclase determination.

Treatment of mouse lymphocytes with very low concentrations of alamethicin or Lubrol PX induces spontaneous permeabilization of the plasma membrane to ATP and allows determination of adenylate cyclase activity in whole cells. The permeabilized cells retain responsiveness to hormones (isoproterenol, adenosine analogs) and to fluoride. The main advantage of this new method is that it does not require any homogenization step, and thus adenylate cyclase activities can be accurately and reproducibly measured with very low amounts of cells. It should be especially useful for the study of purified lymphocyte subpopulations.

Adenosine-induced cyclic AMP increase in pig lymphocytes is not related to adenylate cyclase stimulation.

Adenosine-cyclic AMP relationships have been studied in pig mesenteric lymph node lymphocytes. The early 2--3-fold increase in cyclic AMP accumulation elicited by adenosine and 2-chloroadenosine, an adenosine deaminase-resistant analogue, could not be correlated to similar effects on the adenylate cyclase activity of disrupted cell preparations, but rather to the competitive inhibition of the low Km (0.17 muM) cyclic AMP phosphodiesterase. The existence of adenosine receptors coupled to lymphocyte adenylate cyclase, which had been proposed by several authors, could not be confirmed by this study Adenosine-cyclic AMP relationships do not appear to be involved in concanavalin A stimulation of pig lymphocytes.

Unmasking of membrane enzyme activities and the problem of subcellular localization of adenylate cyclase in pig lymph node lymphocytes.

A large-scale purification of plasma membranes from pig lymph node lymphocytes is described. Centrifugation on a discontinuous sucrose density gradient was performed in a zonal rotor. Adenylate cyclase activity of untreated fractions displayed a profile different from that of plasma membrane enzymatic markers and was maximal at higher density. However, when latent adenylate cyclase was unmasked by Lubrol PX treatment, its maximum was shifted to lower density and was no longer significantly different from that of plasma membrane markers. These results are discussed in terms of cell surface topography.

The proposed 5'-nucleotidase inhibitor in human leukemic cells is an artefact.

It is now well established that human lymphoblastoid cell lines showing immaturity characters display ecto-5'-nucleotidase activities lower than normal levels. A recent paper (Sun, A.S., Holland, J.F. and Ohnuma, T. (1983) Biochim. Biophys. Acta 762, 577-584) mentioned that this phenomenon resulted from the presence of a 5'-nucleotidase inhibitor in these cell lines. We demonstrate here that the use of 5'-[3H]AMP as a substrate, and inadequate analysis of the products formed, led them to a misinterpretation. [3H]Adenosine derived from 5'-[3H]AMP hydrolysis was further transformed into [3H]inosine by the adenosine deaminase activity of the leukemic cell lines tested; [3H]inosine was precipitated with the excess substrate and was not taken into account in the ecto-5'-nucleotidase determination, which led the authors to confuse this adenosine deaminase activity with a 5'-nucleotidase inhibitor. We did not observe 5'-nucleotidase inhibition by leukemic cell cytosol when convenient assay methods were used and showed that the presence of such an inhibitor remains to be established.

Effect of HIV-1 peptide presentation on the affinity constants of two monoclonal antibodies determined by BIAcore technology.

We studied two monoclonal antibodies (MAbs 9-11 and 41-1) which are specific for dominant and conserved epitopes located on HIV-1 transmembrane Gp41. These MAbs recognize both Gp41 and a synthetic HIV-1 envelope peptide (39GC) which is a fragment of Gp41. The interactions between MAbs 9-11 and 41-1 and 39GC either coupled to a sensor chip or to alkaline phosphatase were investigated using BIAcore technology. The association and dissociation rate constants as well as the affinity constants were determined. BIAcore technology allows real-time determination of the interaction between two molecules without the need for any labeling, neither isotopic nor enzymatic. The peptide 39GC was immobilized by coupling to dextran on the BIAcore biosensor through a disulfide bond with a cysteine residue added to the N-terminus of the synthetic peptide. The two native cysteine residues located in the loop of Gp41 were protected by ethylcarbamoyl residues (CONHC2H5); this chemical modification prevented the formation of the S-S bridge and in particular the internal loop. We specifically studied the interaction between the MAbs and either the protected peptide or the peptide whose cysteine residues had been deprotected in situ by alkaline treatment. The results showed that MAb 41-1 recognized 39GC either protected (Ka = 7.6 x 10(6) M-1) or unprotected (Ka = 1.48 x 10(8) M-1), whereas MAb 9-11 recognized only the unprotected form (Ka = 2.18 x 10(8) M-1). Our results suggest that the epitope MAb 9-11 is directed against a part of the peptide sequence which includes the two native cysteines. The difference in affinity observed for MAb 41-1 between the protected and the unprotected forms of 39GC was found to be due to a lower rate of dissociation for unprotected 39GC; these results illustrate the importance of peptide conformation on antibody recognition and might be explained by a conformational change due to reconstitution of the internal loop following deprotection of the thiol groups. MAbs 9-11 and 41-1 also recognized 39GC conjugated to alkaline phosphatase and deprotected. We observed a difference between the rate constants for MAb 41-1 binding to free peptide and its binding to the peptide-enzyme conjugate which might be due to changes in peptide flexibility. In contrast, the rate constants of MAb 9-11 were the same in both experiments, suggesting that the rigidity of the internal loop prevents changes in 9-11 epitope conformation.

Streptabody, a high avidity molecule made by tetramerization of in vivo biotinylated, phage display-selected scFv fragments on streptavidin.

Phage display is a powerful method of isolating of antibody fragments from highly diverse naive human antibody repertoires. However, the affinity of the selected antibodies is usually low and current methods of affinity maturation are complex and time-consuming. In this paper, we describe an easy way to increase the functional affinity (avidity) of single chain variable fragments (scFvs) by tetramerization on streptavidin, following their site-specific biotinylation by the enzyme BirA. Expression vectors have been constructed that enable addition of the 15 amino acid biotin acceptor domain (BAD) on selected scFvs. Different domains were cloned at the C-terminus of scFv in the following order: a semi-rigid hinge region (of 16 residues), the BAD, and a histidine tail. Two such recombinant scFvs directed against the carcinoembryonic antigen (CEA) were previously selected from human non-immune and murine immune phage display libraries. The scFvs were first synthesized in Escherichia coli carrying the plasmid encoding the BirA enzyme, and then purified from the cytoplasmic extracts by Ni-NTA affinity chromatography. Purified biotinylated scFvs were tetramerized on the streptavidin molecule to create a streptabody (StAb). The avidity of various forms of anti-CEA StAbs, tested on purified CEA by competitive assays and surface plasmon resonance showed an increase of more than one log, as compared with the scFv monomer counterparts. Furthermore, the percentage of direct binding of 125I-labeled StAb or monomeric scFv on CEA-Sepharose beads and on CEA-expressing cells showed a dramatic increase for the tetramerized scFv (>80%), as compared with the monomeric scFv (<20%). Interestingly, the percentage binding of 125I-labeled anti-CEA StAbs to CEA-expressing colon carcinoma cells was definitely higher (>80%) than that obtained with a reference high affinity murine anti-CEA mAb (30%). Another advantage of using scFvs in a StAb format was demonstrated by Western blot analysis, where tetramerized anti-CEA scFv could detect a small quantity of CEA at a concentration 100-fold lower than the monomeric scFv.