Space colonization by branching trachea explains the morphospace of a simple respiratory organ.

Branching morphogenesis helps increase the efficiency of gas and liquid transport in many animal organs. Studies in several model organisms have highlighted the molecular and cellular complexity behind branching morphogenesis. To understand this complexity, computational models have been developed with the goal of identifying the "major rules" that globally explain the branching patterns. These models also guide further experimental exploration of the biological processes that execute and maintain these rules. In this paper we introduce the tracheal gills of mayfly (Ephemeroptera) larvae as a model system to study the generation of branched respiratory patterns. First, we describe the gills of the mayfly Cloeon dipterum, and quantitatively characterize the geometry of its branching trachea. We next extend this characterization to those of related species to generate the morphospace of branching patterns. Then, we show how an algorithm based on the "space colonization" concept (SCA) can generate this branching morphospace via growth towards a hypothetical attractor molecule (M). SCA differs from other branch-generating algorithms in that the geometry generated depends to a great extent on its perception of the "external" space available for branching, uses few rules and, importantly, can be easily translated into a realistic "biological patterning algorithm". We identified a gene in the C. dipterum genome (Cd-bnl) that is orthologous to the fibroblast growth factor branchless (bnl), which stimulates growth and branching of embryonic trachea in Drosophila. In C. dipterum, this gene is expressed in the gill margins and areas of finer tracheolar branching from thicker trachea. Thus, Cd-bnl may perform the function of M in our model. Finally, we discuss this general mechanism in the context of other branching pattern-generating algorithms.

Is higher nursing home quality more costly?

Widespread issues regarding quality in nursing homes call for an improved understanding of the relationship with costs. This relationship may differ in European countries, where care is mainly delivered by nonprofit providers. In accordance with the economic theory of production, we estimate a total cost function for nursing home services using data from 45 nursing homes in Switzerland between 2006 and 2010. Quality is measured by means of clinical indicators regarding process and outcome derived from the minimum data set. We consider both composite and single quality indicators. Contrary to most previous studies, we use panel data and control for omitted variables bias. This allows us to capture features specific to nursing homes that may explain differences in structural quality or cost levels. Additional analysis is provided to address simultaneity bias using an instrumental variable approach. We find evidence that poor levels of quality regarding outcome, as measured by the prevalence of severe pain and weight loss, lead to higher costs. This may have important implications for the design of payment schemes for nursing homes.

Assessing the impact of national antibiotic campaigns in Europe.

Because of evidence of causal association between antibiotic use and bacterial resistance, the implementation of national policies has emerged as a interesting tool for controlling and reversing bacterial resistance. The aim of this study was to assess the impact of public policies on antibiotic use in Europe using a differences-in-differences approach. Comparable data on systemic antibiotics administered in 21 European countries are available for a 11-year period between 1997 and 2007. Data on national campaigns are drawn from the public health literature. We estimate an econometric model of antibiotic consumption with country fixed effects and control for the main socioeconomic and epidemiological factors. Lagged values and the instrumental variables approach are applied to address endogeneity aspects of the prevalence of infections and the adoption of national campaigns. We find evidence that public campaigns significantly reduce the use of antimicrobials in the community by 1.3-5.6 defined daily doses per 1,000 inhabitants yearly. This represents an impact of roughly 6.5-28.3 % on the mean level of antibiotic use in Europe between 1997 and 2007. The effect is robust across different measurement methods. Further research is needed to investigate the effectiveness of policy interventions targeting different social groups such as general practitioners or patients.

Quality incentives in a regulated market with imperfect information and switching costs: capitation in general practice.

We model a system akin to the British National Health Service (NHS), in which general practictioners (GPs) are paid by capitation from general taxation. GPs are horizontally and vertically differentiated and compete for patients via their imperfect observed quality. We show that for any given capitation fee quality is lower and the incentive effects of the fee on quality are smaller when there is imperfect information. There are diminishing welfare gains from improving patient information but increasing welfare gains from reducing switching costs. GPs do not act efficiently to improve patient information via advertising or to reduce the costs of switching.

Pulmonary hypertension associated with human immunodeficiency virus infection. Report of two cases and review of the literature.

Recent reports have suggested a possible association between HIV-1 infection and "idiopathic" pulmonary hypertension (PH), but the pathogenetic role of the viral agent has not been fully defined yet. We report the cases of two white males positive for human immunodeficiency virus type 1 (HIV-1) who presented with clinical and hemodynamic diagnosis of pulmonary hypertension. They were heterosexual, non-hemophiliac, heroin abusers with no signs of clinical AIDS. Neither one of the patients had opportunistic lung infections or any other cause of secondary pulmonary hypertension. In one case, peculiar clinical and electrocardiographic features of PH were associated with signs of thrombotic thrombocytopenic purpura (TTP). The association between PH and HIV-1 infection might be explained by a severe alteration of pulmonary endothelial cell homeostasis secondary to HIV-1 viral infection.

Intravitreal and systemic foscarnet in the treatment of AIDS-related CMV retinitis.

Cytomegalovirus retinitis is the most frequent ocular opportunistic infection in AIDS patients. Untreated, it is always a progressive and destructive disease of the retina that results in blindness. Specific treatment is therefore mandatory to halt the progression of the retinal lesions. The authors report their experience in the treatment of CMV retinitis with foscarnet in 25 AIDS patients; the drug is an analog of pyrophosphate, virostatic against all herpes-class viruses including CMV. Foscarnet was successful in halting the progression of CMV retinitis during induction treatment (180 mg/kg/day) by either a TID (three times a day) or a BID (twice a day) regimen, and in healing retinal lesions during maintenance (90 mg/kg/day) in 14 out of 19 patients. Five patients had a relapse of retinitis during maintenance. In these patients a brief course of intravitreal foscarnet, in association with the lowest dosage of the drug administered systematically (90 mg/kg/day), was effective in healing the retinal lesions. The main systemic side effects, such as renal impairment and electrolytic disturbances, were observed only during the induction treatment, and only in one case was it necessary to stop the therapy.