Stefano Colombo

Nasal resistances are useful in identifying children with severe obstructive sleep apnea before polysomnography

OBJECTIVE In this study, we would like to show that anterior rhinometry measurement of nasal resistance would be a simple and useful test to identify severe obstructive sleep apnea (OSA) in a population of children affected by adenotonsillar hypertrophy. METHODS Seventy-three consecutive children (44 males; mean age 5.4+/-1.2 years) with adenotonsillar hypertrophy, who complained sleep-disordered breathing, were studied. All the parents completed a questionnaire concerning the childrens sleeping habits and sleep complaints before consultation; each child underwent a general paediatric examination and an evaluation of craniofacial features and upper airway patency. In all 73 children polysomnography was performed and anterior rhinometry nasal patency was measured. RESULTS The diagnosis of OSA was confirmed in 44/73 patients (60%). Total nasal resistance showed a significant direct correlation with apnea hypopnea index, arousal index, snoring time, percentage of sleep time spent at SaO(2)<90% and a significant inverse correlation with total sleep time, sleep efficiency and the mean of SaO(2)% during sleep. Total nasal resistance was significantly related to snoring, mouth breathing and daytime sleepiness. The receiver operator characteristics (ROC) curve indicates that in the range of age of our sample a nasal resistance value of 0.59 Pa/cm(3)/s has a sensitivity of 91% and specificity of 96% for identifying the children with adenotonsillar hypertrophy affected by OSA. CONCLUSIONS Our study shows that in children with adenotonsillar hypertrophy nasal resistance seems to be risk factor for OSA. The anterior rhinometry appears as a useful tool in routine evaluation of sleep-disordered breathing in these patients.

Virome-associated antibiotic-resistance genes in an experimental aquaculture facility

We report the comprehensive characterization of viral and microbial communities within an aquaculture wastewater sample, by a shotgun sequencing and 16S rRNA gene profiling metagenomic approach. Caudovirales had the largest representation within the sample, with over 50% of the total taxonomic abundance, whereas approximately 30% of the total open reading frames (ORFs) identified were from eukaryotic viruses (Mimiviridae and Phycodnaviridae). Antibiotic resistance genes (ARGs) within the virome accounted for 0.85% of the total viral ORFs and showed a similar distribution both in virome and in microbiome. Among the ARGs, those encoding proteins involved in the modulation of antibiotic efflux pumps were the most abundant. Interestingly, the taxonomy of the bacterial ORFs identified in the viral metagenome did not reflect the microbial taxonomy as deduced by 16S rRNA gene profiling and shotgun metagenomic analysis. A limited number of ARGs appeared to be mobilized from bacteria to phages or vice versa, together with other bacterial genes encoding products involved in general metabolic functions, even in the absence of any antibiotic treatment within the aquaculture plant. Thus, these results confirm the presence of a complex phage-bacterial network in the aquaculture environment.

Streptococcus thermophilus urease activity boosts Lactobacillus delbrueckii subsp. bulgaricus homolactic fermentation

The proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in the yogurt consortium enhances the growth rate and size of each population. In contrast, the independent growth of the two species in milk leads to a slower growth rate and a smaller population size. In this study, we report the first evidence that the urease activity of S. thermophilus increases the intracellular pH of L. delbrueckii in the absence of carbon source. However, in milk, in the presence of lactose the alkalizing effect of urea-derived ammonia was not detectable. Nevertheless, based on glucose consumption and lactic acid production at different pHin, L. delbrueckii showed an optimum of glycolysis and homolactic fermentation at alkaline pH values. In milk, we observed that ammonia provided by urea hydrolysis boosted lactic acid production in S. thermophilus and in L. delbrueckii when the species were grown alone or in combination. Therefore, we propose that urease activity acts as an altruistic cooperative trait, which is costly for urease-positive individuals but provides a local benefit because other individuals can take advantage of urease-dependent ammonia release.

Product Differentiation and Collusion Sustainability When Collusion Is Costly

A widely debated question in recent years by both strategy theorists and antitrust practitioners is what role product differentiation between firms plays in their ability to sustain a collusive agreement in order to reduce the strength of competition and gain higher profits. This paper addresses the following question: What happens to the “product differentiation--collusion sustainability” relationship when setting up and maintaining an agreement is costly? We show that introducing collusion costs into the discussion has relevant implications. Indeed, sufficiently high collusion costs modify the underlying market structure, thus altering the product differentiation--collusion sustainability relationship with respect to the case where collusion costs are absent or low. In particular, if the gains from collusion are increasing decreasing with the degree of product differentiation, the relationship between product differentiation and collusion sustainability is always positive negative, whereas if the gains from collusion are inverted U-shaped, the relationship is inverted U-shaped too. These results stress the importance of considering those markets where the coordination between firms is sufficiently costly as structurally different from those markets where coordination has no costs for firms.

Viromes As Genetic Reservoir for the Microbial Communities in Aquatic Environments: A Focus on Antimicrobial-Resistance Genes

Despite studies of viromes isolated from aquatic environments are becoming increasingly frequent, most of them are limited to the characterization of viral taxonomy. Bacterial reads in viromes are abundant but the extent to which this genetic material is playing a role in the ecology of aquatic microbiology remains unclear. To this aim, we developed of a useful approach for the characterization of viral and microbial communities of aquatic environments with a particular focus on the identification of microbial genes harbored in the viromes. Virus-like particles were isolated from water samples collected across the Lambro River, from the spring to the high urbanized Milan area. The derived viromes were analyzed by shotgun metagenomic sequencing looking for the presence, relative abundance of bacterial genes with particular focus on those genes involved in antimicrobial resistance mechanisms. Antibiotic and heavy metal resistance genes have been identified in all virome samples together with a high abundance of reads assigned to cellular processes and signaling. Virome data compared to those identified in the microbiome isolated from the same sample revealed differences in terms of functional categories and their relative abundance. To verify the role of aquatic viral population in bacterial gene transfer, water-based mesocosms were perturbed or not perturbed with a low dose of tetracycline. The results obtained by qPCR assays revealed variation in abundance of tet genes in the virome and microbiome highlighting a relevant role of viral populations in microbial gene mobilization.

Should a firm engage in behaviour-based price discrimination when facing a price discriminating rival? A game-theory analysis

This article analyses the pricing policy equilibria emerging in a duopoly when one firm may choose whether to engage in behaviour-based price discrimination or uniform pricing while the rival price discriminates. The question we address is: should a firm price discriminate when facing a price discriminating rival? Our main conclusion is that, if the consumers are sufficiently myopic, it is better to choose uniform pricing instead of price discrimination. This is in contrast with the consensus reached in classic price discrimination theory, and it shows that it may be better for a firm to unilaterally renounce to price flexibility when facing a flexible firm.

Imperfect Behavior‐Based Price Discrimination

In this article, we develop a model encompassing behavior-based discriminatory pricing as a limit case of a more general framework where firms have incomplete information about consumers’ purchase histories. We show that information accuracy has a nonmonotonic impact on profits and the worst situation for firms is when information accuracy is intermediate. We also discuss welfare and consumer surplus implications of information accuracy. Although welfare monotonically decreases with the level of information accuracy, there is an inverse U-shape relationship between consumers surplus and information accuracy.

A comment on “welfare reducing licensing”

Abstract This comment points out the existence of flaws in the proof of the main proposition proposed by Fauli-Oller and Sandonis (2002) [Fauli-Oller, R., Sandonis, J., 2002. Welfare reducing licensing. Games Econ. Behav. 41, 192–205] and corrects them.

DOES BEHAVIOUR‐BASED PRICE DISCRIMINATION FOSTER FIRMS’ DIFFERENTIATION?

We study the impact of behaviour‐based price discrimination on the incentive of the firms to differentiate their products. We consider both ‘standard’ and ‘extreme’ behaviour‐based price discrimination: the latter always reduces the incentive to differentiate with respect to uniform pricing, while the former fosters differentiation if the consumers are sufficiently forward‐looking and/or the firms are sufficiently myopic.

Should I stay or should I go? Founder’s decision to leave an entrepreneurial venture during an industrial crisis

Abstract We investigate if while experiencing an intensely negative industry-specific shock, skilled entrepreneurs may decide to leave the firm they founded, whereas founders who are less endowed with human capital may decide to continue their activity. Developing a stylised theoretical framework of the issue intended to derive the necessary and sufficient conditions for the emergence of this phenomenon, this study explores its occurrence in Italy during the ICT industry crisis from early 2000–2003 by analysing the individual stay/leave decision of a sample of 201 founders of 79 start-ups operating in the ICT services market.