[Risk factors for fetal and neonatal brain injury]. / Fattori di rischio per il danno cerebrale fetale e neonatale.

Epidemiological studies have suggested a strong association of fetal and neonatal brain damage with fetal infections and free radical release. Intrauterine infection and hypoxia ischemia appear to share some characteristics, including high levels of cytokines and adhesion molecules. The relevance of the actions of cytokines to a variety of neurological disorders has opened a potentially fruitful area of research and therapeutic development.

Phenotypic tolerance: antibiotic enrichment of noninherited resistance in bacterial populations.

When growing bacteria are exposed to bactericidal concentrations of antibiotics, the sensitivity of the bacteria to the antibiotic commonly decreases with time, and substantial fractions of the bacteria survive. Using Escherichia coli CAB1 and antibiotics of five different classes (ampicillin, ciprofloxacin, rifampin, streptomycin, and tetracycline), we examine the details of this phenomenon and, with the aid of mathematical models, develop and explore the properties and predictions of three hypotheses that can account for this phenomenon: (i) antibiotic decay, (ii) inherited resistance, and (iii) phenotypic tolerance. Our experiments cause us to reject the first two hypotheses and provide evidence that this phenomenon can be accounted for by the antibiotic-mediated enrichment of subpopulations physiologically tolerant to but genetically susceptible to these antibiotics, phenotypic tolerance. We demonstrate that tolerant subpopulations generated by exposure to one concentration of an antibiotic are also tolerant to higher concentrations of the same antibiotic and can be tolerant to antibiotics of the other four types. Using a mathematical model, we explore the effects of phenotypic tolerance to the microbiological outcome of antibiotic treatment and demonstrate, a priori, that it can have a profound effect on the rate of clearance of the bacteria and under some conditions can prevent clearance that would be achieved in the absence of tolerance.

Schirmer tear test results in normal horses and ponies: effect of age, season, environment, sex, time of day and placement of strips.

Tear production was evaluated in 39 horses and 29 ponies using Schirmer tear test strips to determine whether diurnal or weekly fluctuations occur, whether location of strip placement has an effect, if values are the same for both eyes in an animal and whether sex, age, stabling vs. pasture and winter vs. summer had an effect. There was no test in which the raw score was less than 10 mm, although there were many occasions where tear wetting exceeded 35 mm. Analysis of the raw (continuous) scores by linear regression provided no evidence that signalment, housing or season or location of strip placement affected results. The distribution of tear test scores for a 'population' of eyes did not differ when the right eye was compared with the left eye or when the same eye was compared at different times on the same day. Individual test wetting values for opposing eyes measured at the same time, and also wetting values for the same eye measured at different times on the same day sometimes differed substantially. In winter maximum tear wetting exceeded 35 mm more frequently in the STT I than in the STT II even in housed horses and ponies, but there was no consistent significant difference. There appears to be wide variability in the STT I in normal horses and ponies.

Structural and kinetic characterization of native laccases from Pleurotus ostreatus, Rigidoporus lignosus, and Trametes trogii.

A comparative study has been performed on five native laccases purified from the three basidiomycete fungi Pleurotus ostreatus, Rigidoporus lignosus, and Trametes trogii to relate their different catalytic capacities to their structural properties. Spectroscopic absorption features and EPR spectra at various pH values of the five enzymes are very similar and typical of the blue oxidases. The analysis of the dependence of kinetic parameters on pH suggested that a histidine residue is involved in the binding of nonphenolic substrates, whereas both a histidine and an acidic residue may be involved in the binding of phenolic compounds. His and an Asp residue are indeed found at the bottom of a cavity which may be regarded as a suitable substrate channel for approaching to type 1 copper in the 3D homology models of the two laccases from Pleuorotus ostreatus (POXC and POXAlb) whose sequences are known.

Comparison of three fungal laccases from Rigidoporus lignosus and Pleurotus ostreatus: correlation between conformation changes and catalytic activity.

The conformation changes in solution of three fungal laccases in different environmental conditions were examined by circular dichroism (CD) and electron paramagnetic resonance (EPR) spectroscopy. CD measurements indicate that the secondary structure of proteins depends slightly on the pH or ionic strength, though the presence of salt could interfere in the molecular recognition process between substrates and enzymes. The enzymes, however, are highly destabilized by prolonged exposure to low pH or high temperature. The observed unfolding of the proteins coincides with their inactivation and, in some cases, with precipitation. On the other hand, these conditions do not determine the disruption of the geometric arrangement of their metal centres, and this fact suggests that these centres represent the more stable core of the proteins.

A comparative study of two isoforms of laccase secreted by the "white-rot" fungus Rigidoporus lignosus, exhibiting significant structural and functional differences.

Two isoforms of laccase were obtained as the predominant phenol-oxidases in defined medium liquid cultures of the "white-rot" fungus Rigidoporus lignosus (R. lignosus). A characterization of the two laccases was made in terms of molecular mass, isoelectric point, metal content and N-terminal sequence. Furthermore, in order to gain information on the structural features related to the metal centers, a study of their geometric arrangement and their redox ability was made. It turned out that the two isoenzymes greatly differed with regard to pH stability, catalytic and copper centers features. It is proposed that all such differences are dependent on the amino acid sequences, which cause a distortion of the copper sites, thus accounting for the redox potential values and kinetic properties.

[Notes on the development of treatment protocols in epithelial head and neck tumors]. / Nota sintetica sulla evoluzione dei protocolli terapeutici nei tumori epiteliali testa-collo.

Observation of data relating to a lengthy period of clinical activity in the field of head and neck tumours has provided the opportunity for drawing a number of conclusions as regards the prophylaxis of such situations as well as chemo-radiosurgical operating schedules. As regards prophylaxis, particular stress is laid on the worrying number of late diagnoses. In matters of therapy, emphasis is laid on the need for more specific immunological assessments in patients, to guide the physician's decision. The interest of extensive chemotherapeutic experience, which is especially abundant in non-surgical patients, is stressed for the purpose of getting ready for all future developments in the field.