MFI, BEA and FAU zeolite scavenging role in neonicotinoids and radical species elimination.

Ecotoxicity caused by neonicotinoid pesticides is largely due to oxidative stress on non-target species. Due to the fact that reactive radical species reach the environment, materials intended for pesticide removal should be applicable for the simultaneous removal of reactive radicals, as well. This work uses the spectroscopic, adsorptive and antioxidant responses from MFI, FAU and BEA zeolites as descriptors of their potential environmental importance. Different network structures and Si/Al ratios were correlated with excellent zeolite adsorption properties, as over 200 mg g-1 of investigated neonicotinoids, acetamiprid and imidacloprid, was achieved in one cycle. Additionally, after two regeneration steps, over 450 mg g-1 adsorbed pesticides were retained, in three adsorption cycles. Overall the best results were detected for the FAU zeotype in both tested applications, insecticide adsorption and radical-scavenging performance, with and without insecticides present. The proposed mechanism for adsorption relies on kinetic investigation, isotherm modelling and spectroscopic post-adsorption analysis and targets zeolite hydroxyl/siloxane groups as active sites for insecticide adsorption via hydrogen bonding. Neat, well-defined zeolite structures enable their prospective application in ecotoxic species removal.

Control of human and plant fungal pathogens using pentaene macrolide 32, 33-didehydroroflamycoin.

AIMS: The aim of this study was to address the toxicity of recently described polyene macrolide 32, 33-didehydroroflamycoin (DDHR) on a wide range of fungal pathogens and its potential to control plant fungal diseases. METHODS AND RESULTS: The antifungal activity of DDHR in vitro was examined against common human and plant pathogenic fungi using a broth microdilution assay and a disk diffusion assay. Minimum inhibitory concentrations ranged from 12·5 to 35 µg ml(-1) . A radial growth inhibition assay showed that DDHR inhibited mycelia growth, inducing mycelial necrosis and affecting sporulation. During the in vivo assay on apple fruits administration of DDHR 1 h before fungal inoculation inhibited spreading of the infection. Importantly, DDHR exhibited no phytotoxic effects on the model plant, Capsicum annum, verified by the plant growth rate and chlorophyll content. CONCLUSIONS: DDHR inhibits growth of various plant pathogens in vitro with the strongest activity against Alternaria alternata, Colletotrichum acutatum and Penicillium expansum, and protects apple fruits from decay. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of the inhibitory effect of DDHR on important pathogenic fungal isolates. DDHR could be a good scaffold for developing new antifungal agents for fruit and vegetable protection.

Didehydroroflamycoin pentaene macrolide family from Streptomyces durmitorensis MS405(T) : production optimization and antimicrobial activity.

AIMS: The aim of this study was to improve production of pentaene 32,33-didehydroroflamycoin (DDHR) in Streptomyces durmitorensis MS405 strain to obtain quantities sufficient for in depth analysis of antimicrobial properties. METHODS AND RESULTS: Through classical medium optimization conditions for stable growth, DDHR production within 7 days of incubation was established. Yields of 215 mg l(-1) were achieved in shake flask experiments in complex medium with mannitol as the primary carbon source. DDHR had poor antibacterial activity with minimal inhibitory concentrations (MIC) of 400 µg ml(-1) for Staphylococcus aureus and Bacillus subtilis, while MIC of 70 µg ml(-1) was determined for Candida albicans. Using flow cytometry and fluorescent microscopy, it was demonstrated that DDHR induced membrane damage in C. albicans followed by cell death. Combination studies with known antifungal nystatin showed that DDHR is a promising agent for the development of novel antimycotic treatments potentially less toxic for human cells. CONCLUSIONS: Pentaene didehydroroflamycoin has no antibacterial activity but can be further developed for the application in antifungal therapy. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first report on the stable and production in high yields of a novel pentaene family that acts on Candida cell membranes and can be used in combination with known antifungals. Polyenes are still antifungal antibiotics of choice, and therefore, isolation and production of new lead structures are highly significant.

Medium-chain-length polyhydroxyalkanoate production by newly isolated Pseudomonas sp. TN301 from a wide range of polyaromatic and monoaromatic hydrocarbons.

AIMS: The aim of this study was to convert numerous polyaromatic and monoaromatic hydrocarbons into biodegradable polymer medium-chain-length polyhydroxyalkanoate (mcl-PHA). METHODS AND RESULTS: Using naphthalene enrichment cultivation method, we have isolated seven bacterial strains from the river sediment exposed to petrochemical industry effluents. In addition to naphthalene, all seven strains could utilize between 12 and 17 different aromatic substrates, including toluene, benzene and biphenyl. Only one isolate that was identified as Pseudomonas sp. TN301 could accumulate mcl-PHA from naphthalene to 23% of cell dry weight. Owing to poor solubility, a method of supplying highly hydrophobic polyaromatic hydrocarbons to a culture medium was developed. The best biomass and mcl-PHA yields were achieved with the addition of synthetic surfactant Tween 80 (0.5 g l(-1)). We have shown that Pseudomonas sp. TN301 can accumulate mcl-PHA from a wide range of polyaromatic and monoaromatic hydrocarbons, and mixtures thereof, while it could also accumulate polyphosphates and was tolerant to the presence of heavy metal (100 mmol l(-1) cadmium and 20 mmol l(-1) nickel). CONCLUSIONS: A new Pseudomonas strain was isolated and identified with the ability to accumulate mcl-PHA from a variety of aromatic hydrocarbons. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first report on the ability of a bacterial strain to convert a range of polyaromatic hydrocarbon compounds to the biodegradable polymer (mcl-PHA). Mcl-PHA is gaining importance as a promising biodegradable thermoelastomer, and therefore, isolation of new producing strains is highly significant. Furthermore, this strain has the ability to utilize a range of hydrocarbons, which often occur as mixtures and could potentially be employed in the recently described efforts to convert waste materials to PHA.

Is insulin-dependent diabetes and obesity a predisposition for endometrial and pancreatic carcinoma?

Among 178 patients operated for endometrial carcinoma during a five-year period, 17 were re-operated at the Institute of Surgery (9.5%) because of pancreatic head carcinoma. The frequency of insulin-dependent diabetes was pointed out in patients-- 28% of those who were first diagnosed with endometrial carcinoma. Moreover in the same group diagnosed with endometrial carcinoma, we found 17 to have pancreatic carcinoma, and among those there were 12 cases that had diabetes (70.58%).

Ovulation stimulation after treatment for a molar pregnancy for or against?

The case of a 29-year-old patient who underwent invitro fertilization due to secondary sterility, after a spontaneous but molar pregnancy, is described. Afterwards there was no spontaneous conception for five years. With the couple's consent, we decided to perform in vitro fertilization, i.e., ovulation induction and the ICSI (intracytoplasmic sperm injection) method.

The significance of Doppler flow in early detection of uterine sarcoma in older primigravida pregnancies.

During a four-year period we analyzed the significance, sensitivity and sensibility of myoma Doppler flow during pregnancy in relation to the course and outcome of the pregnancy and to later histopathological findings. By following 36 older primigravidas with determined myomas, we observed the course of the pregnancies in all trimesters and analyzed myoma Doppler flow. In conditions where the resistance index showed the possibility of uterine sarcoma, the pregnancy was ended by surgery; not only was myomectomy performed but also complete uterine hysterectomy with the previous consent of the patient. Doppler flow was accepted as the authoritative parameter for non-invasive detection of a malignant process. Considering the obstetrical findings, other patients were delivered vaginally or operatively, but after puerperium they were subjected to control examinations and myomectomy because Doppler flow findings did not show any indications of sarcoma. By histopathological analysis, we received benign results in 31 cases, while in four cases where we decided on hysterectomy and surgical delivery, we received malignant results, i.e. leiomyosarcoma. In four cases of performed hysterectomy immediately after cesarean section, the resistance index (RI) of revascularization within the myoma was in the range between RI 0.30 +/- 0.02. Flows within the uterine artery were 0.54 +/- 0.03.

Gentamicin-resistance determinants confer background-dependent hygromycin B resistance.

Micromonospora strains that produce aminoglycoside antibiotics have a high level of resistance to their own products and to structurally similar antibiotics with a 4,6-disubstituted deoxystreptamine aminocyclitol component such as neomycin, kanamycin, or gentamicin, but these strains remain susceptible to other aminoglycosides such as neomycin and apramycin, in which the aminocyclitol component has different types of substitutions. Therefore, it was surprising that the aminoglycoside-producing Micromonospora strains examined here also showed high-level resistance to hygromycin B, in spite of the fact that this compound has a structurally different aminocyclitol component and a mode of antibacterial action that was also shown to differ somewhat from the mode of action of gentamicin-type antibiotics. When the resistance genes sgm and grm were cloned in Streptomyces lividans and E. coli, they conferred resistance to the expected aminoglycoside compounds but not to hygromycin B. In contrast, introduction of the same resistance genes to M. melanosporea produced resistance to hygromycin B as well. Such an apparent strain dependence in the expression of hygromycin B resistance was also observed with other genes from related genera that are also responsible for aminoglycoside resistance due to methylation of 16S rRNA: of these genes, only kgm assisted expression of hygromycin B resistance and only in the background of M. melanosporea. A possible mechanism for the background dependent of hygromycin B resistance is discussed.

Analysis of plasmid pMZ1 from Micromonospora zionensis.

Plasmid pMZ1, isolated from Micromonospora zionensis, was also able to replicate by the rolling circle mechanism in Micromonospora melanosporea and Streptomyces lividans. Southern hybridisation experiments with probe prepared from pMZ1 and immobilised M. zionesis DNA fragments separated on pulsed-field gel electrophoresis, indicated that the plasmid is present in the progenitor strain in both integrated and autonomous states. Thiostrepton resistant derivatives of pMZ1 plasmid, pMZS25 and pMZS34, were used to study conjugal transfer in M. melanosporea and S. lividans. A 3.4 kb NcoI-MluI fragment from pMZ1 cloned in pIJ702 (plasmid pIJNM3) was shown to be sufficient to promote plasmid transfer and pock formation in S. lividans.

Translational autoregulation of the sgm gene from Micromonospora zionensis.

The sisomicin-gentamicin resistance methylase gene (sgm) from Micromonospora zionensis (the producer of antibiotic G-52 [6-N-methyl-sisomicin]) encodes an enzyme that modifies 16S rRNA and thereby confers resistance to 4,6-disubstituted deoxystreptamine aminoglycosides. Here, we report that this gene is regulated on the translational level. The Escherichia coli lacZ gene and operon fusion system was used, and it was shown that an extra copy of the sgm gene decreases the activity of the fusion protein. These results suggested that expression of the sgm gene is regulated by the translational autorepression because of binding of the methylase to its own mRNA. It was shown by computer analysis that the same hexanucleotide (CCGCCC) is present 14 bp before the ribosome-binding site and in the C-1400 region of 16S rRNA, i.e., the region in which most of the aminoglycosides act. A deletion that removes the hexanucleotide before the gene fusion is not prone to negative autoregulation. This mode of regulation of the sgm gene ensures that enough methylase molecules protect the cell from the action of its own antibiotic. On the other hand, if all of the ribosomes are modified, Sgm methylase binds to its own mRNA in an autorepressive manner.

A genetic study of apramycin-resistant mutants of Escherichia coli.

The apramycin-resistant mutants of E. coli were isolated spontaneously. Mutations, aprA and aprB, conferring resistance to apramycin were located at 72 min on the E. coli genetic map where most of ribosomal genes were mapped. One of the mutants, carrying the aprB mutation, has an altered translational fidelity expressed as severe restriction of amber suppressor activity in vivo. The chromosome location and altered translational fidelity indicate that the apramycin-resistant phenotype could be a consequence of an alteration of the ribosomal structure.

Cloning and characterization of an aminoglycoside resistance determinant from Micromonospora zionensis.

The sisomicin-gentamicin resistance methylase (sgm) gene was isolated from Micromonospora zionensis and cloned in Streptomyces lividans. The sgm gene was expressed in Micromonospora melanosporea, where its own promoter was active, and also in Escherichia coli under the control of the lacZ promoter. The complete nucleotide sequence of 1,122 bp and a transcription start point were determined. The sequence contains an open reading frame that encodes a polypeptide of 274 amino acids. The methylation of 30S ribosomal subunits by Sgm methylase accounts adequately for all known resistance characteristics of M. zionensis, but expression of high-level resistance to hygromycin B is background dependent. A comparison of the amino acid sequence of the predicted Sgm protein with the deduced amino acid sequences for the 16S rRNA methylases showed extensive similarity of Grm and significant similarity to KgmB but not to KamB methylase.

Altered translational fidelity of a Salmonella typhimurium LT2 mutant resistant to the aminoglycoside antibiotic neamine.

A neamine-resistant mutant of Salmonella typhimurium LT2 with altered translational fidelity was isolated. The phenomenon was expressed in severe restriction of amber suppressor activity in vivo as well as in decreased misreading of poly(U) RNA in vitro. The mutation conferring resistance to neamine was mapped at 72 min on the Salmonella genetic map, where some of the ribosomal genes have already been mapped. This location indicates that the neamine-resistant phenotype as well as an altered translational fidelity could be a consequence of an alteration of the ribosomal structure.