Antimicrobial and cytotoxic activity of silver nanoparticles synthesized from two haloalkaliphilic actinobacterial strains alone and in combination with antibiotics.

AIMS: Presently, the effective antimicrobial agents have been limited by the emergence of microbial strains with multidrug resistance and biofilm formation potential. In the present study, we report remarkable antimicrobial activity of silver nanoparticles (AgNPs) synthesized from Streptomyces calidiresistens IF11 and IF17 strains, including inhibition of biofilm formation and synergistic effect of AgNPs and antibiotics against selected bacteria and yeasts. Cytotoxic effect of AgNPs on mammalian cell lines was also evaluated. METHODS AND RESULTS: Analysis of biosynthesized AgNPs by Fourier Transform Infrared Spectroscopy and transmission electron microscopy revealed their spherical shape, small size in the range of 5-50 and 5-20 nm, respectively, as well as the presence of capping agents. Study of antimicrobial activity of AgNPs against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Candida albicans and Malassezia furfur evaluated by minimum inhibitory concentration (MIC) and minimum biocidal concentration (MBC) assays revealed that MICs of AgNPs from IF11 and IF17 strains against bacteria and yeasts were found to be in the range of 16-128 and 8-256 µg ml-1 , while MBCs were in the range of 48-192 and 32-256 µg ml-1 respectively. AgNPs inhibited biofilm formation of microbial strains, which was tested by using crystal violet stain. The highest synergistic effect determined by fractional inhibitory index of AgNPs with antibiotic (kanamycin or tetracycline) was found against Staph. aureus; while in case of yeasts, M. furfur showed highest sensitivity to AgNPs-ketoconazole combination (FIC = 0·12). The cytotoxic activity of AgNPs towards HeLa and 3T3 cell lines was studied by MTT assay. The IC50 of AgNPs estimated against mouse fibroblasts was found to be 8·3 and 28·3 µg ml-1 and, against HeLa cell line, 28·5 and 53·8 µg ml-1 respectively. CONCLUSIONS: It can be concluded that AgNPs synthesized from S. calidiresistens IF11 and IF17 strains have potential as an effective antimicrobial and cytotoxic agent, especially when used in combination with antibiotics/antifungal agents. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicates potential application of biogenic silver nanoparticles as an antimicrobial agent in nanomedicine.

Evaluation of cytotoxicity, immune compatibility and antibacterial activity of biogenic silver nanoparticles.

The study was focused on assessment of antibacterial activity, cytotoxicity and immune compatibility of biogenic silver nanoparticles (AgNPs) synthesized from Streptomyces sp. NH28 strain. Nanoparticles were biosynthesized and characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, nanoparticle tracking analysis system and zeta potential. Antibacterial activity was tested against Gram-positive and Gram-negative bacteria; minimal inhibitory concentration was recorded. Cytotoxicity was estimated using L929 mouse fibroblasts via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Biocompatibility of AgNPs was performed using THP1-XBlue™ cells. Biogenic AgNPs presented high antibacterial activity against all tested bacteria. Minimum inhibitory concentration of AgNPs against bacterial cells was found to be in range of 1.25-10 µg/mL. Silver nanoparticles did not show any harmful interaction to mouse fibroblast cell line, and no activation of nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) cells was observed at concentration below 10 µg/mL. The half-maximal inhibitory concentration (IC50) value was established at 64.5 µg/mL. Biological synthesis of silver can be used as an effective system for formation of metal nanoparticles. Biosynthesized AgNPs can be used as an antibacterial agent, which can be safe for eukaryotic cells.

Study of silver nanoparticles synthesized by acidophilic strain of Actinobacteria isolated from the of Picea sitchensis forest soil.

AIMS: In the present work the acidophilic actinobacteria strain was used as a novel reducing agent for the cheap, green and single-step synthesis of nanostructure silver particles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized by spectroscopy, dynamic light scattering and electron microscopy approach. The antimicrobial activity of silver nanoparticles against clinical strains such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis and Salmonella infantis alone and in combination with antibiotics were studied. METHODS AND RESULTS: The crystalline and stable biosynthesized silver nanoparticles ranged in size from 4 to 45 nm and were mostly spherical in shape being characterized evolving several analytical techniques. The bioAgNPs inhibited growth of most bacterial strains. The highest antimicrobial activity was observed against Ps. aeruginosa (10 mm), followed by Staph. aureus, B. subtilis and Pr. mirabilis (all 8 mm). The lower activity was noticed for E. coli and Kl. pneumoniae (6 and 2 mm, respectively). Moreover, the synergistic effect of bio(AgNPs) with various commercially available antibiotics was also evaluated. The most significant results were observed for bio(AgNPs) combined with tetracycline, kanamycin, ampicillin and neomycin, followed by streptomycin and gentamycin against E. coli, Salm. infantis and Kl. pneumoniae. The most resistant bacteria to commercial antibiotics was Pr. mirabilis. CONCLUSION: The Streptacidiphilus sp. strain CGG11n isolated from acidic soil can be used to efficiently synthesize the bioactive nanoparticles using inexpensive substances in an eco-friendly and nontoxic manner. The present work provides helpful insight into the development of new antimicrobial agents with the synergistic enhancement of the antibacterial mechanism against pathogenic micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: The synthesized silver bionanoparticles from Streptacidiphilus sp. strain CGG11n possess potent inhibitory effect that offers valuable contribution to pharmaceutical associations.

Acidophilic actinobacteria synthesised silver nanoparticles showed remarkable activity against fungi-causing superficial mycoses in humans.

Superficial mycoses are limited to the most external part of the skin and hair and caused by Malassezia sp., Trichophyton sp. and Candida sp. We report extracellular biosynthesis of silver nanoparticles (AgNPs) by acidophilic actinobacteria (SF23, C9) and its in vitro antifungal activity against fungi-causing superficial mycoses. The phylogenetic analysis based on the 16S rRNA gene sequence of strains SF23 and C9 showed that they are most closely related to Pilimelia columellifera subsp. pallida GU269552(T). The detection of AgNPs was confirmed by visual observation of colour changes from colourless to brown, and UV-vis spectrophotometer analysis, which showed peaks at 432 and 427 nm, respectively. These AgNPs were further characterised by nanoparticle tracking analysis (NTA), Zeta potential, Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The FTIR analysis exhibited the presence of proteins as capping agents. The TEM analysis revealed the formation of spherical and polydispersed nanoparticles in the size range of 4-36 nm and 8-60 nm, respectively. The biosynthesised AgNPs were screened against fungi-causing superficial mycoses viz., Malassezia furfur, Trichophyton rubrum, Candida albicans and C. tropicalis. The highest antifungal activity of AgNPs from SF23 and C9 against T. rubrum and the least against M. furfur and C. albicans was observed as compared to other tested fungi. The biosynthesised AgNPs were found to be potential anti-antifungal agent against fungi-causing superficial mycoses.

Schistosoma japonicum infection and rectal carcinoid tumour: underreported coincidence or neglected association?

Schistosoma japonicum infection associated with a rectal carcinoid in an asymptomatic 44-year-old female from the Philippines is described. A systematic review of the literature could not identify similar reports, suggesting a rare coincidence. However, epidemiological data on the frequency of both conditions as well as published results of a colorectal screening programme from China indicate that underreporting of this concurrence is likely. Moreover, several studies suggest a causal link between schistosomiasis caused by S. japonicum and more common gastrointestinal malignancies such as colorectal carcinoma. Hence the presented case and the apparent neglect of this observation in the current literature allow speculation on a role of S. japonicum in the pathogenesis of rare gastrointestinal neoplasms such as carcinoid tumours as well. Future reports on similar observations could help to determine the need for systematic investigations and are strongly encouraged.

[Karyometry of BBN-induced precancerosis of the urothelium : An experimental analysis]. / Karyometrie BBN-induzierter Präkanzerosen des Urothels : Eine experimentelle Analyse.

BACKGROUND: The morphology of experimental precancerous lesions of the urinary bladder has been interpreted quite differently by various authors. OBJECTIVES: The aim of this investigation was to quantify these lesions by karyometry and, thus, to gain a more reliable understanding of the process. MATERIALS AND METHODS: A total of 60 Wistar rats were fed with N­butyl-N-(4-hydroxybutyl)nitrosamine (BBN) at a concentration of 0.05 % in their drinking water to induce preneoplastic changes of the urothelium. After the second week of BBN exposition, 6 animals were killed every 2 weeks up to week 20. Smears of the scraped off urothelium of 3 urinary bladders of each group were analyzed cytologically and karyometrically. RESULTS: BBN exposition led to statistically significant changes of the karyometric values using the χ2 test to differentiate the control animals from the ones that had ingested BBN and the 2­week groups from each other. These changes consisted mainly in significant deviations of the size of the nuclear area within the different groups. CONCLUSION: Morphological and karyometrical analysis showed that biologically relevant stages in the development of chemically induced urothelial precancerous lesions could be realized much earlier than had been assumed in recent publications. Karyometric analysis offered a valid basis to describe the early morphologic alterations of carcinogenesis.

[The ultrastructure of epithelial and myoepithelial oncocytes in the human parotid gland (author's transl)]. / Die Ultrastruktur epithelialer und myoepithelialer Onkozyten in der Glandula parotis des Menschen.

Oncocytes are well known to occur in the tissue of many organs for over 30 years. Their origin and function are less well known. We observed different types of oncocytes in a human parotid gland with the electron microscope. Besides a hyperplasia of mitochondria they show more or less advanced signs of membrane degeneration of these organelles. On the basis of our findings we discuss oncocyte formation as a special form of cellular aging in an otherwise healthy gland.

Application of the Weibull distribution to describe the vertical distribution of cesium-137 on a slope under permanent pasture in Luxembourg.

The application of solutions of the Advection-Dispersion-Equation (ADE) for soil profiles is sometimes questionable. An alternative method, based on the Weibull distribution, has been developed, which can approximate the vertical distribution of radiocesium (137Cs) and allows extrapolation to account for the complete inventory. The structure of the equation allows simple parameters describing the soil depth profile to be derived. Reliable estimates of the total 137Cs inventory can help to explain the lateral distribution. This equation was used to analyse the 137Cs-activities of Chernobyl fall-out measured on a slope under permanent pasture in Luxembourg.

[Frequency of recurrences and tumor progression on superficial bladder carcinoma (author's transl)]. / Rezidivhäufigkeit und Tumorprogression superficialer Harnblasenkarzinome.

A retrospective study with an adequate follow-up of three years or longer of 315 superficial transitional cell carcinomas (Ta--T2) is reported. Patients had transurethral resection in 80% and open excision or resection in 20% for cure or control. It is demonstrated, that in addition to the grade and the stage of the tumor, multifocal tumor growth and whether it is a primary or recurrent tumor influence the frequency of recurrences and the tumor progression. The overall percentage of recurrences after resection of Ta, T1 and T2 tumors within three years is 60%. A primary tumor recurs in 45%, the first recurrence in 84%, solitary tumors in 46% and multifocal tumors in 73%. Tumor progression is observed in solitary tumors in 24%, in multifocal tumors in 44%, in primary and recurrent Ta and primary T1 tumors in 20 to 25%, in recurrent T1 tumors in 56%. Therefore, when planning therapy, stage, grade, multifocal tumor growth and whether it is a primary or recurrent tumor should be considered. Ta tumors can be treated sufficiently by transurethral resection, even in case of several recurrences; more aggressive therapy should be considered, when multifocal or recurrent T1 or T2 tumors recur again as invasive carcinomas.

Rapid identification of Helicobacter pylori by capillary electrophoresis: an overview.

Helicobacter pylori can cause gastritis and peptic ulcers and is directly associated with the development of gastric cancer. There are many types of diagnostic methods used to identification H. pylori (invasive and non-invasive), but these methods usually require time-consuming and laborious procedures and therefore are not capable of fast diagnosis in cases of emergency. This contribution describes the new achievements, interdisciplinary significance and some future directions in the application of capillary electrophoresis for determination of H. pylori.

Generic composition and physiological and cultural properties of heterotrophic bacteria isolated from soil, rhizosphere and mycorrhizosphere of pine (Pinus silvestris L.).

Among the bacteria studied Arthrobacter globiformis was predominating in the root zone, while in the non-rhizosphere soil most numerous were Bacillus circulans and A. globiformis. Ammonifiers were more numerous among the root zone bacteria than among the root free soil organisms. The reverse was noted with bacteria capable of hydrolysing starch, cellulose, pectin and chitin.

Metabolic activity of bacteria isolated from soil, rhizosphere and mycorrhizosphere of pine (Pinus silvestris L.).

Casamino acids were found to be the best substrate for bacteria isolated from soil, rhizosphere and mycorrhizosphere of pine. Most active with this substrate were however the root zone bacteria. Glucose was oxidized similarly by the bacteria isolated from the three sources.

Motile cells in the mucosa of the cloacal urodaeum and proctodaeum of the hen. An electron microscopic study.

Motile cells (mast cells, granulocytes, lymphoid cells) are described in the mucosa of the cloacal urodaeum and proctodaeum of the female domestic fowl. Diffuse lymphoid tissue with lymphatic nodules occurs in the urodaeum at the ureteral ostium. Small local aggregations of lymphoid tissue can be observed in the mucosa of the proctodaeum. Cells originating from these sites penetrate the basal lamina of the epithelium and are then found between the epithelial cells. In the subepithelial layers the motile cells sometimes are in contact with each other. Mast cells (tissue basophils) form contact zones, resembling desmosomes or half desmosomes, with smooth muscle cells. In the mast cells three types of granules can be distinguished. Their ultrastructure is discussed in comparison with that in similar cells of the guinea pig.

Scanning electron microscope observations of microvascular anastomosis in the rat carotid artery.

Microvascular anastomosis is gaining increasing significance in the field of replantation and reconstructive surgery. Although traumatic interference is minimized by microsurgery, thrombotic occlusions remain the major reason for clinical failure. With the improvement of suturing technique studies were directed towards the causes of failure using light and scanning electron microscopy. Our study was focussed on the latter aspect. The left common carotid artery of 55 albino rats was transsected and re-anastomosed by the eccentric biangulation technique. The suture-lines were observed after various postsurgical intervals, ranging from 12 hours up to 14 months. Twelve hours after the anastomosis had been performed, the most striking alterations of the endothelium were not found at the suture line, as was expected, but in those parts of the vessels, which were caught by the clamps. The injury leads to sloughing of the endothelium in extensive areas. The exposed subendothelial layer of connective tissue is covered with aggregates of thrombocytes. The suture itself does not lead to thrombus formation. After 14 days, healing is almost complete with total regeneration of the endothelium. From the 21st postoperative day on, the inner lining can no longer be differentiated from that found in experimental animals after 14 months.

Prognostic parameters in superficial bladder cancer: an analysis of 315 cases.

A retrospective study of 315 patients with superficial transitional cell carcinoma (stages Ta to T2) and an adequate followup of 3 years or longer is reported. Transurethral resection was done in 80 per cent of the patients and open excision or resection was done in 20 per cent for cure or control. We herein demonstrate that, in addition to grade and stage, multifocal tumor growth and whether the tumor is primary or recurrent influence the frequency of recurrences and tumor progression. The over-all recurrence rate after resection of stages Ta, T1 and T2 tumors within 3 years was 60 per cent. Recurrences after a primary tumor were noted in 45 per cent of the patients and were followed by a second recurrence in 84 per cent, with solitary tumors occurring in 46 and multifocal tumors in 73 per cent. Tumor progression was observed in 24 per cent of patients with solitary tumors, 44 per cent of those with multifocal tumors, 20 to 25 per cent of those with primary and recurrent stage Ta and primary stage T1 tumors, and 56 per cent of those with recurrent stage T1 tumors. Therefore, when therapy is planned stage, grade, multifocal tumor growth and whether the tumor is primary or recurrent should be considered. Stage Ta tumors can be treated sufficiently by transurethral resection even in the case of several recurrences. More aggressive therapy should be considered when multifocal or recurrent stage T1 or T2 tumors recur as invasive carcinomas.