Inflammatory and mechanical factors of allergen-induced bronchoconstriction in mild asthma and rhinitis.

We studied whether different bronchial responses to allergen in asthma and rhinitis are associated with different bronchial inflammation and remodeling or airway mechanics. Nine subjects with mild asthma and eight with rhinitis alone underwent methacholine and allergen inhalation challenges. The latter was preceded and followed by bronchoalveolar lavage and bronchial biopsy. The response to methacholine was positive in all asthmatic but in only two rhinitic subjects. The response to allergen was positive in all asthmatic and most, i.e., five, rhinitic subjects. No significant differences between groups were found in airway inflammatory cells or basement membrane thickness either at baseline or after allergen. The ability of deep inhalation to dilate methacholine-constricted airways was greater in rhinitis than in asthma, but it was progressively reduced in rhinitis during allergen challenge. We conclude that 1) rhinitic subjects may develop similar airway inflammation and remodeling as the asthmatic subjects do and 2) the difference in bronchial response to allergen between asthma and rhinitis is associated with different airway mechanics.     

Fungal parasitism in freshwater calanoid population: ecological consequences and possible mechanisms involved in the infection process

This paper reports the results of a study on a zoosporic fungus (Saprolegniaceae) parasitizing populations of Eudiaptomus intermedius (Copepoda, Calanoida) in mountain lakes located in the Northern Apennines, Italy. The dynamics of this infectious process was previously described in one of the lakes of the study area. The virulence is particularly high at the end of the calanoid reproductive phase, when the fungal hyphae penetrate the host eggs provoking their degeneration. Here new data are presented and the phenology of the host–parasite interaction is comparatively analyzed in different years and in different sites. The occurrence of the parasite was assessed at a regional scale. Possible mechanisms involved in the pathogen dispersal and in the host recognition are proposed, and the ecological impact of the fungal parasitism on the calanoid populations is discussed.     

Recent ostracods (Crustacea,Ostracoda) found in lowland springs of the provinces of Piacenza and Parma (Northern Italy)

The “fontanili” are artificial aquatic ecosystems, typical of the lowland plains of Northern Italy, exploiting natural resurgences of deep groundwater. These habitats are characterized by low variation in hydrologic, hydrochemical and thermal conditions throughout the year. Proper management is required to prevent the spring clogging by biomass accumulation. In spite of their importance as refugia for endangered species, many springs were completely abandoned in the last years and several of them will disappear. We report the results of a study carried out in 2001 on 31 springs of the provinces of Piacenza and Parma, distributed in seven areas defined on hydrological and geological considerations. Physical and chemical variables and parameters of waters were measured and ostracod samples were collected. Most of the springs showed high nitrate concentration, due to a diffuse pollution of agricultural origin. Twelve ostracod species in four families were identified. Ostracod valves were analysed by scanning electron microscopy. Cypria ophtalmica was found in all the springs; other relatively common species were Cyclocypris laevis,Notodromas persica, and Prionocypris zenkeri.The maximum number of species per site was four. Cypridopsis vidua,P. zenkeri, and N. persicashowed a very localized distribution in the study area. The ostracod fauna of the “fontanili” was compared to other species assemblages found in spring habitats and to the available information on recent freshwater ostracods reported for Italy.     

Aeromonas Hydrophila and its Relation with Drinking Water Indicators of Microbiological Quality in Argentine

In Argentine, water municipal supplies disinfection is carried out by chlorine. We have isolated Aeromonas hydrophilafrom a chlorinated water supply in Buenos Aires that fulfilled Argentinean microbiological quality standards. It is an aquatic organism that could produce cytotoxins and enterotoxins associated with acute gastroenteritis and wound infections in human and hemorrhagic septicaemia of fish, reptiles and amphibians. The isolated strain produced protein bands at isoelectric point in the range of 4.6–5.3 lightly labile at 56°C and heat labile at 100°C non cholera antitoxin reactive in electrofocusing assay (IEF) and showed hemolytic activity thermolabile at 56°C and 100°C in 5% rabbit erythrocytes in phosphate buffered saline. A cytotoxic effect thermolabile at 56°C and 100°C and a cytotonic activity were demonstrated in Vero cell cultures. Survival assay of A. hydrophilaand indicator organisms would show no correlation between their contamination sources. Biofilms production could explain the persistence of this gram negative pathogen organism in chlorinated tap water. A water system supply maintenance program and pasteurisation may be performed in spite of water chlorination.     

Tetracycline affects abnormal properties of synthetic PrP peptides and PrP(Sc) in vitro

Prion diseases are characterized by the accumulation of altered forms of the prion protein (termed PrP(Sc)) in the brain. Unlike the normal protein, PrP(Sc) isoforms have a high content of beta-sheet secondary structure, are protease-resistant, and form insoluble aggregates and amyloid fibrils. Evidence indicates that they are responsible for neuropathological changes (i.e. nerve cell degeneration and glial cell activation) and transmissibility of the disease process. Here, we show that the antibiotic tetracycline: (i) binds to amyloid fibrils generated by synthetic peptides corresponding to residues 106-126 and 82-146 of human PrP; (ii) hinders assembly of these peptides into amyloid fibrils; (iii) reverts the protease resistance of PrP peptide aggregates and PrP(Sc) extracted from brain tissue of patients with Creutzfeldt-Jakob disease; (iv) prevents neuronal death and astrocyte proliferation induced by PrP peptides in vitro. NMR spectroscopy revealed several through-space interactions between aromatic protons of tetracycline and side-chain protons of Ala(117-119), Val(121-122) and Leu(125) of PrP 106-126. These properties make tetracycline a prototype of compounds with the potential of inactivating the pathogenic forms of PrP.     

Prophylaxis and treatment of bacterial infections: do we need new strategies?

Bacterial infections in patients with hematologic malignancies still represent a severe and life-treating problem. Several observational studies during the last decade have revealed that neutropenic patients with fever are a heterogeneous population with various differences regarding response to initial therapy, development of serious complications and mortality. The role of neutropenia as main risk factor for infections in hematologic patients and the definition of different level of risk related to neutrophils count and duration of neutropenia have been extensively studied and different categories of patients based on the risk of infection, mostly the condition of neutropenia, have been clearly defined. The strategies on antimicrobial therapy and supportive care in hematologic patients need to be continuously assessed, in fact new conditions favouring the occurrence of infectious complications in patients with hematologic malignancies have progressively emerged. The use of oral prophylactic antibiotics in neutropenic cancer patients is still a matter of debate. Before 2005, several trials showed how the prevention of infection can be extremely important in this setting of patients but none was conclusive. In 2005 two meta-analysis and two large randomized clinical trials gave new evidence that antibacterial prophylaxis can reduce in neutropenic patients several important outcomes including mortality. The use of the empiric antibacterial therapy represents the cornerstone of the antimicrobial strategies in the febrile neutropenic patients leading, over the span of 20 years, to a dramatic decrease of deaths: Actually beta-lactam monotherapy is commonly used for the empiric treatment of febrile neutropenia. Recently, large randomized clinical trials and meta-analysis showed that the addition of an aminoglycoside and/or a glycopeptides results in a more favourable outcome only in selected severe infections. The use of antibiotics should be prudent and safe also in neutropenic hematologic patients to prevent emergence of microbial resistance, to save costs, to reduce toxicity. For this reasons, according to the evidence, antibacterial prophylaxis should be restricted to high risk hematologic patients and empiric parenteral antibiotic monotherapy should be recommended in case of febrile neutropenia limiting the use of amynoglicosides and glycopeptides. In the next future, a major effort should be made to state in hematologic patients new risk factors which could more accurately define subgroups for targeted anti-infective strategies.     

Beta2-microglobulin isoforms display an heterogeneous affinity for type I collagen

It has been claimed that beta2-microglobulin (beta2-m) interacts with type I and type II collagen, and this property has been linked to the tissue specificity of the beta2-m amyloid deposits that target the osteo-articular system. The binding parameters of the interaction between collagen and beta2-m were determined by band shift electrophoresis and surface plasma resonance by using bovine collagen of type I and type II and various isoforms of beta2-m. Wild-type beta2-m binds collagen type I with a Kd of 4.1 x 10(-4) M and type II with 2.3 x 10(-3) M. By the BIAcore system we monitored the binding properties of the conformers of the slow phase of folding of beta2-m. The folding intermediates during the slow phase of folding do not display any significant difference with respect to the binding properties of the fully folded molecule. The affinity of beta2-m truncated at the third N-terminal residue does not differ from that reported for the wild-type protein. Increased affinity for collagen type I is found in the case of N-terminal truncated species lacking of six residues. The Kd of this species is 3.4 x 10 (-5) M at pH 7.4 and its affinity increases to 4.9 x 10(-6) M at pH 6.4. Fluctuations of the affinity caused by beta2-m truncation and pH change can cause modifications of protein concentration in the solvent that surrounds the collagen, and could contribute to generate locally a critical protein concentration able to prime the protein aggregation.     

Biodegradation of chemically modified flax fibers in soil and in vitro with selected bacteria

The extent and rate of degradation of flax (Linum usitatissimum) fibers, both in the native state and after surface chemical modification (acetylation or poly(ethylene glycol), PEG, grafting), was investigated under laboratory conditions in two different biodegrading environments. Degradation of the fibers under aerobic conditions by the action of the microorganisms present in soil is assessed with the ASTM 5988-96 method by monitoring carbon dioxide evolution. In vitro biodegradation experiments were carried out by exposing the fibers to a pure culture of Cellvibrio fibrovorans bacteria and measuring the mass loss as a function of time. Despite the complexity of the system, the results of degradation in soil were satisfactorily reproducible, although the absolute rates were found to change in different experiments using the same soil. The degradation rate of acetylated fibers in soil nearly equals that of unmodified fibers, whereas in the pure culture, acetylated fibers biodegrade slower than native fibers. The opposite happens with the PEG-grafted fibers, which degrade slower than unmodified flax in soil and at a comparable rate upon in vitro exposure to the bacterial culture. The different biodegradation kinetics observed in the two biodegrading environments were attributed to differences of biocenoses, abiotic factors, and biodegradation assessing methods. Nevertheless, the final extent of biodegradation was the same for modified and unmodified fibers both in soil and in the pure culture, showing that the surface chemical modifications applied do not significantly affect biodegradability of the flax fibers.     

Time-Lapse Imaging of Conformational Changes in Supercoiled DNA by Scanning Force Microscopy

Most of the scanning force microscopy (SFM) images of supercoiled DNA on untreated mica thus far reported have not shown tight plectonemic structure seen by electron microscopy, but instead less coiled molecules and sometimes a partly "condensed" state with intimate chain-chain interactions. By observing time-lapse images of conformational changes of DNA induced by decreasing ionic strength of imaging buffer in solution SFM, we could show that the process of water rinsing, an indispensable step for preparation of dried samples, may be responsible for some of the conformational anomalies in the images previously reported. We have studied several protocols to observe supercoiled DNA molecules by SFM and discuss the merits and the demerits. Images obtained following uranyl acetate treatment may be ideal for the detection of DNA damage, as the supercoiled and nicked forms are easily distinguishable.