Hot spots become cold spots: coevolution in variable temperature environments.

Antagonistic coevolution between hosts and parasites is a key process in the genesis and maintenance of biological diversity. Whereas coevolutionary dynamics show distinct patterns under favourable environmental conditions, the effects of more realistic, variable conditions are largely unknown. We investigated the impact of a fluctuating environment on antagonistic coevolution in experimental microcosms of Pseudomonas fluorescens SBW25 and lytic phage SBWΦ2. High-frequency temperature fluctuations caused no deviations from typical coevolutionary arms race dynamics. However, coevolution was stalled during periods of high temperature under intermediate- and low-frequency fluctuations, generating temporary coevolutionary cold spots. Temperature variation affected population density, providing evidence that eco-evolutionary feedbacks act through variable bacteria-phage encounter rates. Our study shows that environmental fluctuations can drive antagonistic species interactions into and out of coevolutionary cold and hot spots. Whether coevolution persists or stalls depends on the frequency of change and the environmental optima of both interacting players.

Vertically transmitted symbiont reduces host fitness along temperature gradient.

Parasites with exclusive vertical transmission from host parent to offspring are an evolutionary puzzle. With parasite fitness entirely linked to host reproduction, any fitness cost for infected hosts risks their selective elimination. Environmental conditions likely influence parasite impact and thereby the success of purely vertical transmission strategies. We tested for temperature-dependent virulence of Caedibacter taeniospiralis, a vertically transmitted bacterial symbiont of the protozoan Paramecium tetraurelia. We compared growth of infected and cured host populations at five temperatures (16­32 °C). Infection reduced host density at all temperatures, with a peak of −30% at 28 °C. These patterns were largely consistent across five infected Paramecium strains. Similar to Wolbachia symbionts, C. taeniospiralis may compensate fitness costs by conferring to the host a 'killer trait', targeting uninfected competitors. Considerable loss of infection at 32 °C suggests that killer efficacy is not universal and that limited heat tolerance restricts the conditions for persistence of C. taeniospiralis.

Assessment of pulmonary function in a follow-up of premature infants: our experience.

Respiratory diseases are a major cause of morbidity in neonates, especially preterm infants; a long term complication of prematurity such as bronchopulmonary dysplasia (BPD) is particularly relevant today. The exact role of the Pulmonary Function Test (PFT) in this area is not yet well defined; the PFT in newborns and infants - in contrast to what happens in uncooperative children and adults - are routinely used only in a few centers. The assessment of pulmonary function in newborns and infants, however, is nowadays possible with the same reliability that in cooperative patients with the possibility to extend the assessment of polmonary function from bench to bed. The assessment of pulmonary function must be carried out with non invasive and safe methods, at the bedside, with the possibility of continuous monitoring and providing adequate calculation and management of data. The ability to assess lung function helps to define the mechanisms of respiratory failure, improving the treatment and its effects and is therefore a useful tool in the follow-up of newborn and infant with pulmonary disease.

[Assessment of pulmonary function in a follow-up of premature infants: our experience]. / Valutazione della funzionalità respiratoria nell'ambito di un follow up respiratorio di neonati prematuri: la nostra esperienza.

Respiratory diseases are a major cause of morbidity in neonates, especially preterm infants; a long-term complication of prematurity such as bronchopulmonary dysplasia (BPD) is particularly relevant today. The exact role of the Pulmonary Function Test (PFT) in this area is not yet well defined; the PFT in newborns and infants--in contrast to what happens in uncooperative children and adults--are routinely used only in a few centers. The assessment of pulmonary function in newborns and infants, however, is nowadays possible with the same reliability that in cooperative patients with the possibility to extend the assessment of polmonary function from bench to bed. The assessment of pulmonary function must be carried out with non invasive and safe methods, at the bedside, with the possibility of continuous monitoring and providing adequate calculation and management of data. The ability to assess lung function helps to define the mechanisms of respiratory failure, improving the treatment and its effects and is therefore a useful tool in the follow-up of newborn and infant with pulmonary disease.

Role of atypical bacteria in children undergoing tonsillectomy because of severely recurrent acute tonsillopharyngitis.

The aim of this study was to verify the frequency of atypical bacterial infections in children undergoing tonsillectomy because of severely recurrent acute tonsillopharyngitis (AT) and the possible benefit of surgery in cases in which Mycoplasma pneumoniae and Chlamydophila pneumoniae seem to play a role in causing the recurrences. A total of 118 patients (76 males; mean age +/- standard deviation, 6.67 +/- 3.31 years) were enrolled: 59 underwent tonsillectomy because of severely recurrent AT and 59 underwent adenotonsillectomy because of obstructive sleep apnea syndrome (OSAS). The results show, for the first time, that the great majority of children with a history of severely recurrent AT (and, therefore, considered to be eligible for elective tonsillectomy) are infected by atypical bacteria, mainly M. pneumoniae, and that tonsillectomy seems to be effective in reducing the recurrence of both AT and acute respiratory disease during 12 months follow-up postsurgery.

Paranasal sinuses and middle ear infections: what do they have in common?

Otitis media and sinusitis are among the most common pediatric diseases and they share common features. Although the anatomy, physiology and disease processes are not identical, knowledge of the pathophysiology of middle ear disorders often provides to the pediatrician a useful understanding of sinus diseases. The same risk factors identified for otitis media may play a pivotal role in the development of sinusitis. Moreover, as both paranasal sinuses and middle ear acquire respiratory pathogens from nasopharynx, acute sinusitis is usually caused by the same bacterial pathogens that cause acute otitis media, with a major role for Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis, while anaerobes may predominate in chronic disease. A responsibility of bacterial biofilms in chronic sinusitis, similarly to otitis media, has been recently suggested. Biofilms, three-dimensional aggregates of bacteria, are refractory to antibiotics and thus might explain why some patients improve while on antibiotics but relapse after completion of therapy.