In vitro candidacidal activity of a synthetic killer decapeptide (KP) against Candida albicans cells adhered to resin acrylic discs.

BACKGROUND: Oral Candida spp., and C. albicans in particular, are considered as important aetiological agents in the pathogenesis of denture-induced stomatitis. Several studies have reported that C. albicans is able to easily adhere to different medical devices, such as vascular and urinary catheters or acrylic denture surfaces, and that adhesion is a fundamental step in the initial pathogenic process of colonization and further possible infection. Recently, a synthetic decapeptide (KP) derived from the sequence of a single-chain recombinant anti-idiotypic antibody, acting as a functional internal image of a microbicidal, broad spectrum yeast killer toxin, has been reported to kill in vitro C. albicans cells and to exert a therapeutic activity against experimental mucosal and systemic candidiasis. METHODS: The aim of this study was to evaluate, through a CFU assay, the candidacidal activity of KP on sanded acrylic resin discs, previously colonized by C. albicans cells. RESULTS AND CONCLUSIONS: At 100 microg/ml KP showed over 90% of killing activity on C. albicans cells adhered to resin discs, when compared with a scramble peptide used as control. The results of this study suggest a potential effect of KP on C. albicans cells adhered on the surface of resin materials, such as prosthetic dentures.

Engineered killer mimotopes: new synthetic peptides for antimicrobial therapy.

This review deals with a novel approach to produce synthetic antibiotic peptides (killer mimotopes), similar to those described for the conversion of epitopes into peptide mimotopes, allowing their use as surrogate vaccines. Synthetic peptides pertaining to the complementary determining regions (CDRs) of a recombinant antiidiotypic antibody (PaKTscFv), which mimic the wide spectrum of microbicidal activity of a killer toxin produced by the yeast Pichia anomala (PaKT), have proven to act as structural or functional mimotopes of PaKT. This activity appeared to be mediated by interaction with specific cell wall killer toxin receptors (KTRs), mainly constituted by beta glucans. Killer mimotopes have shown in vitro an impressive microbicidal activity against Candida albicans. They were adopted as a model of PaKT- and PaKTscFv-susceptible microorganisms. Optimization through alanine scanning led to the generation of an engineered decapeptide (KP) of a CDR-L1 pertaining antibody fragment with an enhanced in vitro microbicidal activity. It had a potent therapeutic effect against experimental vaginal and systemic candidiasis in normal and immunodeficient mice caused by flucanozole susceptible and resistant yeast isolates. KP exerted a microbicidal activity in vitro against multidrug-resistant eukaryotic and prokaryotic pathogenic microorganisms, which was neutralized by interaction with laminarin (beta 1,3-glucan). To our knowledge, KP represents the prototype of an engineered peptide fragment derived from a microbicidal recombinant antiidiotypic antibody. It is capable of exerting antimicrobial activity in vitro and a therapeutic effect in vivo presumably acting through interaction with the beta glucan KTR component in the cell walls of pathogenic microorganisms.

Internal tandem duplications of Flt3 gene (Flt3/ITD) predicts a poor post-remission outcome in adult patients with acute non-promyelocytic leukemia.

Despite progress in AML therapy, most patients eventually relapse, even the ones with normal or favorable karyotype. Since survival is poor once relapse occurs, new genetic tools above karyotype at diagnosis are needed to predict leukemia free survival. Recently, Flt3/ITD has been reported as an independent marker for clinical outcome in most studies concerning adult AML patients. To assess the prognostic relevance of activating mutations of Flt3, pretreatment samples of 100 not-M3 AML patients, all of them subjected to an intensive chemotherapy regimen, were analyzed for Flt3/ITD; 25/100 patients had one or more Flt3-ITD. Flt3/ITD patients had higher WBC count (P = 0.005), a lower incidence of a preceding MDS (P = 0.004) and most of them had a normal karyotype. Flt3/ITD had no impact on CR achievement while karyotype remained the most powerful prognostic factor (HR 2.8 95% CI 1.2 6.3). However, post-remission outcome was significantly worsened by the presence of Flt3/ITD. Median RFS of the Flt3/ITD patients was 5 vs. 27 months compared to the patients with wild-type Flt3 (P = 0.0002); moreover, Flt3/ITD patients had a significantly poorer post-remission survival (11 vs. 38 months, P = 0.01). On multivariate analysis, the presence of Flt3-ITD significantly affected relapse free survival and post-remission survival (HR 3.1 and 2.1, respectively). Thus, post-remission outcome highly depends on Flt3 status. Flt3 mutations identify patients at high risk of relapse, who should prospectively receive, according to age, either more aggressive or alternative therapeutic approaches.

Biotechnological approaches to the production of idiotypic vaccines and antiidiotypic antibiotics.

The potential therapeutic activity of a killer toxin produced by the yeast Pichia anomala (PaKT) characterized by its wide spectrum of antimicrobial activity has been exploited through the simulation of its interaction with the specific cell wall receptor (KTR) of PaKT-sensitive microorganisms by the idiotypic network. Killer antiidiotypes (PaKTantiId) produced by idiotypic vaccination with a PaKT-neutralizing monoclonal antibody have proven to confer active and passive immunoprotection in experimental models of systemic and vaginal candidiasis. PaKTantiId-like human anti-KTR antibodies are naturally produced in infections caused by PaKT-sensitive microorganisms. PaKTantiId in its monoclonal and recombinant formats as well as expressed on human commensal bacteria have shown microbicidal activity in vitro and a therapeutic effect in experimental models of infection caused by PaKT-sensitive microorganisms. New perspectives of idiotypic vaccination and antiidiotypic antibiotic therapy and biotechnological approaches to the production of trandisease idiotypic vaccines and wide-spectrum antiidiotypic antibiotics (killer mimotopes) will be discussed as effective tools to fight epidemiologically important mucosal and systemic microbial infections.

Killer anti-idiotypes in the control of fungal infections.

Killer anti-idiotypes (KTantild) bear the internal image of a Pichia anomala toxin (KT), characterized by microbicidal activity against prokaryotic and eukaryotic pathogenic microorganisms presenting specific cell wall receptors (KTR). KTantiId produced by idiotypic vaccination with a KT-neutralizing monoclonal antibody confer active and passive immunoprotection in experimental models of systemic and vaginal candidiasis. KTantild-like human natural anti-KTR antibodies are produced in natural infections caused by KT-sensitive microorganisms. KTantiId in the monoclonal and recombinant forms show therapeutic activity in experimental vaginal candidiasis and Pneumocystis carinii pneumonia. Human commensal bacteria expressing KTantild or killer mimotopes synthesized from the sequence of KtantiId, may represent effective tools to combat fungal infections.

In vitro activity of monoclonal and recombinant yeast killer toxin-like antibodies against antibiotic-resistant gram-positive cocci.

BACKGROUND: Monoclonal (mAbKT) and recombinant single-chain (scFvKT) anti-idiotypic antibodies were produced to represent the internal image of a yeast killer toxin (KT) characterized by a wide spectrum of antimicrobial activity, including gram-positive cocci. Pathogenic eukaryotic and prokaryotic microorganisms, such as Candida albicans, Pneumocystis carinii, and a multidrug-resistant strain of Mycobacterium tuberculosis, presenting specific, although yet undefined, KT-cell wall receptors (KTR), have proven to be killed in vitro by mAbKT and scFvKT. mAbKT and scFvKT exert a therapeutic effect in vivo in experimental models of candidiasis and pneumocystosis by mimicking the functional activity of protective antibodies naturally produced in humans against KTR of infecting microorganisms. The swelling tide of concern over increasing bacterial resistance to antibiotic drugs gives the impetus to develop new therapeutic compounds against microbial threat. Thus, the in vitro bactericidal activity of mAbKT and scFvKT against gram-positive, drug-resistant cocci of major epidemiological interest was investigated. MATERIALS AND METHODS: mAbKT and scFvKT generated by hybridoma and DNA recombinant technology from the spleen lymphocytes of mice immunized with a KT-neutralizing monoclonal antibody (mAb KT4) were used in a conventional colony forming unit (CFU) assay to determine, from a qualitative point of view, their bactericidal activity against Staphylococcus aureus, S. haemolyticus, Enterococcus faecalis, E. faecium, and Streptococcus pneumoniae strains. These bacterial strains are characterized by different patterns of resistance to antibiotics, including methicillin, vancomycin, and penicillin. RESULTS: According to the experimental conditions adopted, no bacterial isolate proved to be resistant to the activity of mAbKT and scFvKT. CONCLUSIONS: scFvKT exerted a microbicidal activity against multidrug resistant bacteria, which may represent the basis for the drug modeling of new antibiotics with broad antibacterial spectra to tackle the emergence of microbial resistance.

[The clinical, angiographic and procedural predictors of thrombosis and restenosis in Micro stent II (AVE) coronary stents]. / Predittori clinici, angiografici e procedurali di trombosi e di restenosi in stent coronarici Micro stent II (AVE).

The aim of the study was to assess the incidence and the predictors of thrombosis and restenosis in Micro stent II AVE. In a sample of 197 stents successfully implanted in 181 consecutive patients, the incidence of thrombosis was 4.1%. The multivariate analysis showed the minimum lumen diameter post-stenting to be the only independent predictor of overall thrombosis. In fact, we found that the risk of thrombosis increases as the minimal lumen diameter decreases. Angiographic follow-up was available in 74% of the stents at 6.8 +/- 4.1 months and stent restenosis occurred in 26.2% of cases. Independent predictors of restenosis (multivariate linear discriminant analysis) were: 1) nominal stent diameter (the risk of restenosis decreases as the stent diameter increases); 2) the ratio between the diameter of the balloon carrying the stent measured at the maximum pressure/nominal stent diameter (the risk increases as the ratio decreases); 3) stented vessel (the risk increases in the following order: right coronary < circumflex < left anterior descending); 4) the American Heart Association classification of lesion morphology (the risk increases in the order A < B < C); 5) a lower risk was found in the absence of diabetes mellitus.

A transphyletic anti-infectious control strategy based on the killer phenomenon.

A strategy for the prevention and control of candidiasis, pneumocystosis, and tuberculosis, based on the idiotypic network of the yeast killer effect has been envisaged. Anti-idiotypic antibodies representing the internal image of a candidacidal, pneumocysticidal, and mycobactericidal killer toxin from Pichia anomala and idiotypes of killer toxin-neutralizing monoclonal antibodies mimicking the specific cell wall receptor of sensitive microorganisms might provide a unique approach for engineering innovative antibiotics and vaccines active against taxonomically unrelated pathogenic microorganisms. The rationale of the strategy relies on a phenomenon of microbial competition which has been mutated by the immune system in the response to natural infections.

Neonatal mouse immunity against group B streptococcal infection by maternal vaccination with recombinant anti-idiotypes.

We investigated whether immunization with recombinant anti-idiotypic antibody fragments mimicking the conformation of the capsular antigen can protect against infection by group B streptococcus, an important neonatal pathogen. Single-chain fragment-variable anti-idiotypes competed with the type III carbohydrate for binding to type-specific antibodies and elicited, in mice, the production of protective immunoglobulins reacting against the type III polysaccharide. Moreover, maternal immunization with soluble or phage-displayed fragments protected neonatal mice against streptococcal infection. These data indicate that recombinant anti-idiotypic antibodies may be useful in developing protein images of relevant carbohydrate epitopes and, ultimately, in preventing infections by encapsulated bacteria.

Mycobactericidal activity of human natural, monoclonal, and recombinant yeast killer toxin-like antibodies.

Human natural (KTAb), murine monoclonal (KTMAb), and single-chain recombinant (KTScFv) candidacidal antibodies representing the internal image of a killer toxin from the yeast Pichia anomala (KT), characterized by a wide spectrum of antibiotic activity, exerted a lethal effect against a KT-sensitive multidrug-resistant isolate of Mycobacterium tuberculosis. KTMAb and KTScFv were produced by the hybridoma and DNA technologies, respectively, from the spleen lymphocytes of animals immunized with the idiotype of a KT-neutralizing MAb (MAb KT4), while KTAb were purified against MAb KT4 from the vaginal fluid of women infected with Candida albicans cells bearing an idiotype-like KT cell wall receptor. Mycobactericidal activity was related to the binding of KTAb, KTMAb, and KTScFv to the cell surface of KT-sensitive bacterial cells and was prevented by specific absorption of KT-like antibodies onto MAb KT4. These data identify a novel potentially useful immunotherapeutic approach to tuberculosis.

[Reliability of M-mode and B-mode echocardiography in detection of left intra-atrial masses (author's transl)]. / Affidabilita' della ecocardiografia M-mode/B-mode nella identificazione delle masse intra-atriali sinistre.

Although the role of echocardiography in the detection of left atrial masses is well established, reliability of the method is yet unknown. In 312 patients who underwent cardiac surgery, echocardiographic and anatomic findings were confronted. Pre-operative diagnosis was confirmed in the 8 cases with prolapsing tumors: in the remaining patients we had 5 false positive and 9 false negative diagnosis. So in our experience, sensibility has 73.5 and specificity 98.20.

[Fixed subvalvular left ventricular outflow tract obstruction. Comparison of the diagnostic usefulness of mono- and bi-dimensional echocardiography]. / Ostacolo all'efflusso del ventricolo sinistro sottovalvolare fisso. Confronto tra utilità diagnostica della ecocardiografia mono-bidimensionale.

Because Cross-Sectional Echocardiography offers the advantage of correct spatial orientation, it is said to permit a more exact localization of the level of the outflow tract obstruction and a determination of the nature of the lesion. Our experience confirms that B-Mode Echo is more reliable in diagnosing an extensive sub-valvular narrowing, while the existence of a thin sub-valvular membrane can also be detected by M-Mode examination. The latter has moreover proven very useful in that it records indirect signs of obstruction, such as a mid-systolic closure of the aortic cusps. We therefore suggest that both methods should be employed in studying these patients.

[The pathology of mitral porcine valves. Echocardiographic relief in 5 cases with intra-para-prosthetic regurgitation (author's transl)]. / Patologia delle protesi mitraliche porcine. Rilievi ecocardiografici in cinque casi con rigurgito intra-para-protesico.

Echocardiograms were performed in five patients with severe mitral porcine valve insufficiency due to the para-valvular leak in three cases and to a torn and flail cusp in two cases. We believe that diastolic fluttering of the vusps, decrease or increase of diastolic slope of either the stent or the anterior leaflet as well as decrease of the amplitude of motion of the leaflets cannot be regarded as typical diagnostic features as previously described. In our experience specific signs are only represented by a chaotic diastolic movement of one or both leaflets.

[Right atrial angiosarcoma. report of a case treated successfully by surgery (author's transl)]. / Angiosarcoma dell'atrio destro. Aspetti clinici, ecocardiografici ed istologici in un caso operato con successo.

A 32 years old male presented with symptoms and signs of congestive heart failure. The echocardiographic and angiographic examinations demonstrated a large right atrial tumor prolapsing in the right ventricle through the tricuspid orifice. The patient underwent successful surgical resection of the tumor. Histologically in the lesion was diagnosed as angiosarcoma.

[Mitral insufficiency due to rupture of chordae tendineae. The diagnostic usefulness of M-mode echocardiography (author's transl)]. / Insufficienza mitralica da rottura di corde tendinee. Utilità diagnostica della ecocardiografia bidimensionale.

Mitral insufficiency due to ruptured chordae tendinaee is not easily diagnosed by M-mode Echocardiography: of the several patterns that have been described, none has proven quite reliable. Two-dimensional study, on the other hand, seems to be more useful in that it permits to identify an abnormal movement of the involved leaflet which appears quite characteristic. Out of a group of 14 patients we were able to diagnose chordal rupture in 5 proven cases. Further investigation is necessary to ascertain specificity and sensitivity if this echo pattern.