Highly sensitive FRET-based fluorescence immunoassay for detecting of aflatoxin B1 using magnetic/silica core-shell as a signal intensifier

Background: recently, some new nanobiosensors using different nanoparticles or microarray systems for detection of mycotoxins have been designed . However, rapid, sensitive and early detection of aflatoxicosis would be very helpful to distinguish high-risk persons

Objectives: we report a highly sensitive competitive immunoassay using magnetic/silica core shell as a signal intensifier for the determination of aflatoxin B1 using fluorescence resonance energy transfer [FRET] from Cd/Te quantum dots [antiaflatoxin B1 antibody immobilized on the surface of Cd/Te quantum dots] to Rhodamine 123 [Rho 123-labeled aflatoxin B1 bound to albumin]. The specific immune-reaction between the anti-aflatoxin B1 antibody on the QDs and the labeledaflatoxin B1 brings the Rho 123 fluorophore [acting as the acceptor] and the QDs [acting as the donor] in close spatial proximity and causes FRET to occur upon photo-excitation of the QDs. Using magnetic/silica core shell to intensify the obtained signal is the novelty of this study

Materials and Methods: Cd/Te QDs were synthesized by the simultaneous reduction of cadmium chloride and tellurium in the presence of sodium borohydride under nitrogen atmosphere. Magnetic nanoparticles were synthesized using FeSO[4] and FeCl[3] [1:2 molar ratio] and ammonia as an oxidizing agent under nitrogen atmosphere. The prepared magnetic nanoparticles shelled by silica using tetraethoxysilane in the presence of ammonia. Nanoparticles synthesis and monodispersity confirmed by TEM. Immobilization of Cd/Te QDs to antibodies and labeling of aflatoxin B1-albumin by Rho 123 were performed by EDC/NHS reaction in reaction mixture buffer, pH 6, at room temperature

Results: by using the magnetic/silica core shell sensitivity of the system changed from 2×10[-11] in our previous study to 2×10[-12] in this work. The feasibility of the method established by the detection of aflatoxin B1 in spiked human serum. There is a linear relationship between the decreased fluorescence intensity of Rho 123 with increasing concentration of aflatoxin B1 in spiked samples, over the range of 0.01-0.06 [micro]mol.mL[-1]

Conclusions: this homogeneous competitive detection scheme is simple, rapid and efficient, and does not require multiple separation steps and excessive washing

Actinomycosis in Iran: short narrative review article

Actinomycosis is an indolent, slowly progressive infection caused by anaerobic or microaerophilic bacteria, primarily of genus Actinomyces, which colonize the mouth, colon and vagina. Mucosal disruption may lead to infection virtually at any sites in the body. The aim of this study was to underline different features of actinomycosis and to represent total data about etiologic agents, clinical, diagnostic and therapeutic approaches these infections. From a total of 38 case reports or series, ninety one cases were obtained by using of relevant articles reported as recorded cases in Iran [1972 to 2012]. Analyzed data represented 21 cases of oral-servicofacial [23.1%], 7 cases of thoracic [7.7%], 17 cases of abdominal [18.7%], 21 cases of disseminated forms [23.1%] and 25 cases of others [27.5%]. Findings indicated more common of these infections in men [61.5%]. Actinomyces naeslundii [21 cases] was found as the most common causative agents in comparison with A. Israeli [15 cases], A. viscosus [3 cases] and A. bovis [1 case]. The most patients had been successfully treated with penicillin although some cases needed surgery along with antibiotic therapy. Since some clinical features of actinomycosis are similar to malignancies, so the differential diagnosis of invasive forms must be considered. This report emphasizes on the importance of differential diagnosis of actinomycosis from similar diseases by clinicians

[Microscopic examination in quantifying of Malassezia yeast in scalp and rapid diagnosis of fungi invasive condition: a brief report]

Malassezia Species are often commensal of the human skin and scalp that opportunistically in exist of particular predisposing factors, their proliferation increases; as, in dandruff and seborrheic dermatitis which both togather affect more than 50% of humans, the excess proliferation of yeast in scalp, leads to scalp-flaking and causes physical and mental disorder in peaple, spacially in youth that their health and hiar hygiene and beauty is more important for them. Thus, this survey has been done for rapid, easy and inexpensive method to diagnosis of abnormal proliferation and invasive condition of Malassezia yeast and can be more benefical for proper treatment. Sampling with scalpel scraping from scalp of volunteer persons that had not bathed at least two day ago were done and preparation of direct microscopic slides and staining with methylene blue were accomplished. Then, survey of morpholgic characteristics, yeast quantification and mycelium detection were done by direct microscopic examination. From 140 scalp samples of adult persons of both gender [male and female] with different age groups, observation of malassezia yeast in 93.5% [131] were positive and 6.5% [9] were negative in direct microscopic examination. Results of yeast quantification in positive cases were: mild or normal flora 25.2%, intermediate 24.5%, severe 50.3%. Detection of mycelium in positive cases were 22.9% [30] [P=0.007 df=2]. Application of an accessible, easy and inexpensive method and a determinated pattern [yeast quantification with direct microscopic examination] to distinguish normal flora from abnormal condition [excess proliferation and mycelium production] in cases of Malassezia yeasts can be more useful to rapid diagnosis of abnormal proliferation and invasive condition in order to initiate a proper antifungal treatment.

In-vitro activity of 10 antifungal agents against 320 dermatophyte strains using microdilution method in Tehran

Dermatophyte fungi are the etiologic agents of skin infections commonly referred to as ringworm. These infections are not dangerous but as a chronic cutaneous infections they may be difficult to treat and can also cause physical discomfort for patients. They are considered important as a public health problem as well. No information is available regarding the efficacy of antifungal agents against dermatophytes in Tehran. Therefore, in this study we evaluated the efficacy of 10 systemic and topical antifungal medications using CLSI broth microdilution method [M38-A]. The antifungal agents used included griseofulvin, terbinafine, itraconazole, ketoconazole, fluconazole, voriconazole, clotrimazole, ciclopiroxolamine, amorolfine and naftifine.Fifteen different species of dermatophytes which were mostly clinical isolates were used as follows; T. mentagrophytes, T. rubrum, E. floccosum, M. canis, T. verrucosum, T. tonsurans,M. gypseum, T. violaceum, M. ferruginum,M. fulvum, T. schoenleinii, M. racemosum, T. erinacei,T.eriotriphon and Arthrodermabenhamiae. The mean number of fungi particles [conidia] inoculated was 1.25 x 10[4] CFU/mL. Results were read after 7 days of incubation at 28 °C. According to the obtained results,itraconazole and terbinafine showed the lowest and fluconazole had the greatest MIC values for the most fungi tested. Based on the results, it is necessary to do more research and design a reliable standard method for determination of antifungal susceptibility to choose proper antibiotics with fewer side effects and decrease antifungal resistance and risk of treatment failure

In vitro susceptibility of aflatoxigenic and non-aflatoxigenic aspergillus flavus strains to conventional antifungal agents

Presently appearance of resistance to antifungal agents among Aspergillus species is dramatically increasing. The objective of this study was to look at the in vitro activities of antifungal drugs against Iranian clinical [from nail, bronchoalveolar lavage, paranasal sinus] isolated A. flavus strains. The susceptibility of 45 aflatoxigenic and non-aflatoxigenic Aspergillus flavus strains were evaluated to six antifungal agents [caspofungin, itraconazole, amphotericin B, ketoconazole, fluconazole, nystatin] using CLSI M38-A2 broth microdilution method. The results indicated that 57.1%, 28.6% of aflatoxigenic and 25.8%, 6.5% of nonaflatoxigenic isolates were susceptible to caspofungin, amphotericin B respectively. All isolates but one aflatoxigenic strain were sensitive to ketoconazole. All 45 strains showed to be resistant to nystatin. Also 64.28%, 92.9% of aflatoxigenic and 64.51%, 100% of non-aflatoxigenic isolates were resistant to fluconazole and itraconazole in ranking order. There was no statistically significant difference between the susceptibilities of aflatoxigenic and non-aflatoxigenic strains of A. flavus to tested antifungal agents