Kinetics of hybridization to human DNA of heterogeneous nuclear RNA isolated from normal human lymphoblasts and acute leukemia blast cells

Heterogeneous nuclear RNA was extracted from normal PHA-stimulated human lymphocytes and acute myeloid leukemia blast cells. Experiments were performed to determine the hybridization kinetics of these RNAs to human DNA. The best least squares solutions indicate in the hybridization reaction of both normal and leukemic RNA two main components. For leukemic cell RNA the rate constants of both components were significantly different from that of normal cell RNA. In particular, the difference between the rate constants of the second slower component suggests that the slowly hybridizing sequences in leukemic cell RNA have a degree of repetition higher than that of the corresponding sequences of normal cell RNA.     

N-acetylcysteine prevents TNF-induced mitochondrial damage,apoptosis and viral particle production in HIV-infected U937 cells

It has been hypothesized that reactive oxygen intermediates (ROI) can activate human immunodeficiency virus (HIV) replication and that HIV can trigger programmed cell death (PCD). In this work, we studied PCD in U937 cultured cells chronically infected with HIV and exposed to tumor necrosis factor alpha (TNFα). This cytokine has been shown to induce apoptosis in some cell types and to produce intracellular free radical species including ROI. In addition, it was also demonstrated that HIV-induced PCD observable in U937 infected cells can be favored by TNF exposure. In one of our recent works, evidence was presented that the thiol supplier N-acetylcysteine (NAC) can ‘protect’, at least partially, HIV-infected cells from PCD and determine a significant decrease in viral progeny. In the present work, we demonstrate (a) that apoptosis can be easily induced by TNF only in infected U937 cells and not in control wild-type cells, (b) that daily treatment of TNF-exposed cells with low concentrations of NAC is able to impair viral progeny formation as early as 24 h, (c) that the mitochondrial damage induced by TNF is counteracted by preexposure to NAC, and (d) that NAC alone exerts changes in mitochondria which may be responsible for the protective effects exerted by this compound. Because of the radical producing capacity of TNF, these results seem to indicate that the protective effects of NAC may be due to the specific antioxidant nature of this substance which appears to be capable of impairing both the apoptotic machinery and viral replication by an intracellular mechanism involving mitochondrial integrity and function.     

The polar lipids of Clostridium psychrophilum, an anaerobic psychrophile

We have examined the polar lipids of Clostridium psychrophilum, a recently characterized psychrophilic Clostridium isolated from an Antarctic microbial mat. Lipids were extracted from cells grown near the optimal growth temperature (+ 5 °C) and at − 5 °C, and analyzed by two-dimensional thin layer chromatography and liquid chromatography coupled with mass spectrometry. The major phospholipids of this species are: cardiolipin, phosphatidylethanolamine, and phosphatidylglycerol. Phosphatidylserine and lyso-phosphatidylethanolamine were found as minor components. The most abundant glycolipids are a monoglycosyldiradylglycerol (MGDRG) and a diglycosyldiradylglycerol (DGDRG). The latter was only seen in cells grown at − 5 °C. An ethanolamine-phosphate derivative of N-acetylglucosaminyldiradylglycerol was seen in cells grown at − 5 °C and an ethanolamine-phosphate derivative of MGDRG was found in cells grown at + 5 °C. All lipids were present in both the all acyl and plasmalogen (alk-1′-enyl acyl) forms with the exception of PS and MGDRG, which were predominantly in the diacyl form. The significance of lipid changes at the two growth temperatures is discussed.     

Rhamnolipids are conserved biosurfactants molecules: implications for their biotechnological potential

A range of isolates of Pseudomonas aeruginosa from widely different environmental sources were examined for their ability to synthesise rhamnolipid biosurfactants. No significant differences in the quantity or composition of the rhamnolipid congeners could be produced by manipulating the growth conditions. Sequences for the rhamnolipid genes indicated low levels of strain variation, and the majority of polymorphisms did lead to amino acid sequence changes that had no evident phenotypic effect. Expression of the rhlB and rhlC rhamnosyltransferase genes showed a fixed sequential expression pattern during growth, and no significant up-regulation could be induced by varying producer strains or growth media. The results indicated that rhamnolipids are highly conserved molecules and that their gene expression has a rather stringent control. This leaves little opportunity to manipulate and greatly increase the yield of rhamnolipids from strains of P. aeruginosa for biotechnological applications.     

Cunninghamella elegans biomass optimisation for textile wastewater biosorption treatment: an analytical and ecotoxicological approach

The effect of pre-treatments on the composition of Cunninghamella elegans biomass and on its biosorption yields in the treatment of simulated textile wastewaters was investigated. The inactivated biomass was subjected to physical treatments, such as oven drying and lyophilisation, and chemical treatments using acid or alkali. The wastewater colour, COD and toxicity variations were evaluated. The lyophilisation sped up the biosorption process, whereas the chemical pre-treatment changed the affinity of biomass for different dyes. The alkali per-treated biomass achieved the highest COD reduction in the treatment of alkali wastewaters, probably because no release of alkali-soluble biomass components occurred under the alkaline pH conditions. Accordingly, only the acid pre-treated biomass decreased the COD of the acidic effluent. The ecotoxicity test showed significant toxicity reduction after biosorption treatments, indicating that decolourisation corresponds to an actual detoxification of the treated wastewaters. Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analyses of biomasses allowed highlighting their main chemical and physical properties and the changes induced by the different pre-treatments, as well as the effect of the chemical species adsorbed from wastewaters.     

Influence of Culture Medium on Fungal Biomass Composition and Biosorption Effectiveness

Zygomycetes such as Cunninghamella elegans seem to be promising biosorbents for pollutants removal from wastewaters because of their particular cell wall characteristics. In this article the effect of ten culture media on C. elegans biomass composition was investigated by means of Fourier transform infra red spectroscopy (FTIR). Biomasses grown on starches from potatoes and cereals were characterised by high amount of chitin and polysaccharides, the glucose gave rise to a biomass rich in acidic polysaccharides and lipids. By contrast, biomasses grown on corn steep liquor were poor in acidic polysaccharides and, when N sources and micronutrients were added, rich in proteins. The lipid content of the biomass generally increased by halving nutrients. Biosorption yields of these biomasses towards four wastewater models were assessed in terms of colour, salts and toxicity reduction. The biomasses rich in proteins and acid polysaccharides were less effective in removing reactive and direct dyes, whereas those rich in cationic polysaccharides showed a higher affinity for these dyes. Both chromatography and FTIR analyses showed that biomasses cultured in halved C and N had the highest affinity for salts. The wastewaters detoxification was quite always achieved, with values often lower that the Italian legal threshold limit.     

S-nitrosoglutathione incorporated in poly(ethylene glycol) matrix: potential use for topical nitric oxide delivery.

Incorporation of nitric oxide (NO) donors in non-toxic polymeric matrices can be a useful strategy for allowing topical NO delivery. We have incorporated the NO-donor S-nitrosoglutathione (GSNO) into a liquid poly(ethylene glycol) (PEG)/H2O matrix through the S-nitrosation of GSH by a NO/O2 gas mixture. Kinetic measurements of GSNO decomposition associated with NO release were performed at 25, 35, and 45 degrees C in the dark and under irradiation with UV/Vis light, lambda>480 nm and lambda=333 nm. NO release from the liquid matrix to the gas phase was confirmed by mass spectrometry. The PEG/H2O matrix stabilizes GSNO leading to expressive reductions in the initial rates of thermal and photochemical NO release, compared to aqueous GSNO solution. This matrix effect is assigned to diffusional constrains imposed on the escape of the NO and GS radicals formed in the solvent cage. This effect allows the storage of PEG-GSNO formulations for extended periods (more than 65 days at freezer) with negligible decomposition. PEG-GSNO formulation seems therefore to be applicable in topical NO delivery and GSNO displays potential as a percutaneous absorption enhancer. Moreover, the rate of NO release can be locally increased by irradiation with visible light.     

Antimicrobial resistance and production of toxins in Escherichia coli strains from wild ruminants and the alpine marmot

Escherichia coli strains isolated from 81 fecal samples from red deer (Cervus elaphus), roe deer (Capreoulus capreoulus), chamois (Rupicapra rupicapra) and alpine marmot (Marmota marmota) living in the Stelvio National Park, Italy, were examined for antimicrobial resistance and production of toxic factors. Direct plating of specimens on media containing antimicrobial drugs allowed us to isolate resistant strains of E. coli from 10 of 59 (17%) specimens examined by this technique. Nine of 31 specimens from red deer (29%) contained resistant strains. Different animals were likely colonized by the same resistant strain of E. coli. Conjugative R plasmids were found in four strains isolated from the marmot, roe deer and chamois. A strain from red deer produced heat-stable enterotoxin and another strain produced both hemolysin and cytotoxic necrotizing factor. A marmot isolate produced hemolysin alone. No strains were found to produce heat-labile enterotoxin or verotoxins.     

Differential effects of c-myb and c-fes antisense oligodeoxynucleotides on granulocytic differentiation of human myeloid leukemia HL60 cells

To gain some insight into the role of c-myb and c-fes in myeloid differentiation, the authors have analyzed the ability of HL60 cells to differentiate in response to several different inducers after inhibition of c-myb and c-fes function. This function has been inhibited almost completely by using deoxynucleotides complementary to two 18-nucleotide sequences of c-myb and c-fes encoding mRNA. After 5 days in culture, in several separate experiments with different oligomer preparations, more than 90% growth inhibition was observed in c-myb antisense-treated HL60 cells. At this time, independent of the differentiation inducer used, c-myb antisense-treated HL60 cells differentiate only along the monocytic pathway, whereas in sense oligomer-treated cultures, retinoic acid and dimethyl sulfoxide induced granulocytic differentiation. No perturbation of the HL60 cell growth was observed after 5 days of treatment with antisense c-fes oligomer. However, induction to granulocytic differentiation by retinoic acid and dimethyl sulfoxide resulted in progressive cell death, whereas monocytic differentiation by other differentiation inducers was only marginally affected. These results suggest that granulocytic, unlike monocytic, differentiation requires c-myb-conditioned proliferation and the activity of the protein encoded by c-fes.