Modeling Ventilator-Induced Lung Injury and Neutrophil Infiltration to Infer Injury Interdependence

Acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI) are heterogeneous conditions. The spatiotemporal evolution of these heterogeneities is complex, and it is difficult to elucidate the mechanisms driving its progression. Through previous quantitative analyses, we explored the distributions of cellular injury and neutrophil infiltration in experimental VILI and discovered that VILI progression is characterized by both the formation of new injury in quasi-random locations and the expansion of existing injury clusters. Distributions of neutrophil infiltration do not correlate with cell injury progression and suggest a systemic response. To further examine the dynamics of VILI, we have developed a novel computational model that simulates damage (cellular injury progression and neutrophil infiltration) using a stochastic approach. Optimization of the model parameters to fit experimental data reveals that the range and strength of interdependence between existing and new damaged regions both increase as mechanical ventilation patterns become more injurious. The interdependence of cellular injury can be attributed to mechanical tethering forces, while the interdependence of neutrophils is likely due to longer-range cell signaling pathways.

Open questions in the social lives of viruses

Social interactions among viruses occur whenever multiple viral genomes infect the same cells, hosts, or populations of hosts. Viral social interactions range from cooperation to conflict, occur throughout the viral world, and affect every stage of the viral lifecycle. The ubiquity of these social interactions means that they can determine the population dynamics, evolutionary trajectory, and clinical progression of viral infections. At the same time, social interactions in viruses raise new questions for evolutionary theory, providing opportunities to test and extend existing frameworks within social evolution. Many opportunities exist at this interface: Insights into the evolution of viral social interactions have immediate implications for our understanding of the fundamental biology and clinical manifestation of viral diseases. However, these opportunities are currently limited because evolutionary biologists only rarely study social evolution in viruses. Here, we bridge this gap by (1) summarizing the ways in which viruses can interact socially, including consequences for social evolution and evolvability; (2) outlining some open questions raised by viruses that could challenge concepts within social evolution theory; and (3) providing some illustrative examples, data sources, and conceptual questions, for studying the natural history of social viruses.

Spatiotemporal distribution of cellular injury and leukocytes during the progression of ventilator-induced lung injury

Supportive mechanical ventilation is a necessary lifesaving treatment for acute respiratory distress syndrome (ARDS). This intervention often leads to injury exacerbation by ventilator-induced lung injury (VILI). Patterns of injury in ARDS and VILI are recognized to be heterogeneous; however, quantification of these injury distributions remains incomplete. Developing a more detailed understanding of injury heterogeneity, particularly how it varies in space and time, can help elucidate the mechanisms of VILI pathogenesis. Ultimately, this knowledge can be used to develop protective ventilation strategies that slow disease progression. To expand existing knowledge of VILI heterogeneity, we document the spatial evolution of cellular injury distribution and leukocyte infiltration, on the micro- and macroscales, during protective and injurious mechanical ventilation. We ventilated naïve mice using either high inspiratory pressure and zero positive end-expiratory pressure ventilation or low tidal volume with positive end-expiratory pressure. Distributions of cellular injury, identified with propidium iodide staining, were microscopically analyzed at three levels of injury severity. Cellular injury initiated in diffuse, quasi-random patterns, and progressed through expansion of high-density regions of injured cells termed "injury clusters." The density profile of the expanding injury regions suggests that stress shielding occurs, protecting the already injured regions from further damage. Spatial distribution of leukocytes did not correlate with that of cellular injury or ventilation-induced changes in lung function. These results suggest that protective ventilation protocols should protect the interface between healthy and injured regions to stymie injury propagation.

Acceptability of male circumcision and predictors of circumcision preference among men and women in Nyanza Province, Kenya

Numerous epidemiologic studies report significant associations between lack of male circumcision and HIV-1 infection, leading some to suggest that male circumcision be added to the limited armamentarium of HIV prevention strategies in areas where HIV prevalence is high and the mode of transmission is primarily heterosexual. This cross-sectional survey of 107 men and 110 women in Nyanza Province, Kenya, assesses the attitudes, beliefs, and predictors of circumcision preference among men and women in a traditionally non-circumcising region. Sixty per cent (n=64) of uncircumcised men and 69% (n=68) of women who had uncircumcised regular partners reported that they would prefer to be circumcised or their partners to be circumcised. Men's circumcision preference was associated with the belief that it is easier for uncircumcised men to get penile cancer, sexually transmitted diseases, and HIV/AIDS, and that circumcised men have more feeling in their penises, enjoy sex more, and confer more pleasure to their partners. Women with nine or more years of school were more likely to prefer circumcised partners. Men who preferred to remain uncircumcised were concerned about the pain and cost of the procedure, and pain was a significant deterrent for women to agree to circumcision for their sons. If clinical trials prove circumcision to be efficacious in reducing risk of HIV infection, it is likely that the procedure will be sought by a significant proportion of the population, especially if it is affordable and minimally painful.

Feasibility of medical male circumcision in Nyanza Province, Kenya

BACKGROUND

Over forty observational studies have reported a protective effect of male circumcision against HIV-I acquisition, leading some to suggest that male circumcision be added to the limited armamentarium of HIV prevention strategies.

OBJECTIVES

To evaluate the feasibility and requirements of implementing medical male circumcision in Nyanza Province of Kenya a quasi-experimental design was implemented to assess clinicians' knowledge of male circumcision and to assess the effectiveness of a one day educational intervention in one district. A cross sectional survey assessed the availability of necessary instruments and surgical supplies.

RESULTS

None of the participating ten health facilities had all the necessary instruments and supplies to safely perform male circumcisions. Though most clinicians reported training about circumcision, most lacked sufficient knowledge to perform the procedure, and few were familiar with the process of informed consent. We demonstrated that a didactic educational workshop significantly improved providers' knowledge of male circumcision.

CONCLUSIONS

Since increasing numbers of young men and parents are requesting male circumcision services in many parts of sub-Saharan Africa, health providers must undergo further training in the performance of the procedure and the process of informed consent. Many health facilities will have to be provided with the instruments and supplies necessary to perform male circumcision safely.

Health care providers' experience reporting child abuse in the primary care setting. Pediatric Practice Research Group

OBJECTIVES

To describe (1) primary care providers' experiences identifying and reporting suspected child abuse to child protective services (CPS) and (2) variables affecting providers' reporting behavior.

DESIGN AND METHODS

Health care providers (76 physicians, 8 nurse practitioners, and 1 physician assistant) in a regional practice-based network completed written surveys that collected information about the demographic characteristics of each provider and practice; the provider's career experience with child abuse; and the provider's previous year's experience identifying and reporting suspected child abuse, including experience with CPS.

RESULTS

All providers (N = 85) in 17 participating practices completed the survey. In the preceding 1 year, 48 respondents (56%) indicated that they had treated a child they suspected was abused, for an estimated total of 152 abused children. Seven (8%) of 85 providers did not report a total of 7 children with suspected abuse (5% of all suspected cases). A majority of providers (63%; n = 29) believed that children who were reported had not benefited from CPS intervention, and 21 (49%) indicated that their experience with CPS made them less willing to report future cases of suspected abuse. Providers who had some formal education in child abuse after residency were 10 times more likely to report all abuse than were providers who had none.

CONCLUSIONS

Primary care providers report most, but not all, cases of suspected child abuse that they identify. Past negative experience with CPS and perceived lack of benefit to the child were common reasons given by providers for not reporting. Education increases the probability that providers will report suspected abuse.