Search results for "Infectious"

The population genetics and evolutionary epidemiology of RNA viruses.

2004

Key Points The authors discuss the main mechanisms of RNA virus evolution — mutation, recombination, natural selection, genetic drift and migration, and how these interact to shape the genetic structure of populations.The quasispecies model of RNA virus evolution is explained and the question of whether this model provides an accurate description of RNA virus evolution is discussed.Experiments that can be carried out to test the basic principles of evolutionary theory are briefly described. The authors review what such experiments have told us about virus evolution and, more widely, what these experiments have revealed in terms of general evolutionary principles.RNA viruses evolve quickly, …

Facial masks in children: the position statement of the Italian pediatric society

2020

AbstractFacial masks may be one of the most cost-effective strategies to prevent the diffusion of COVID 19 infection. Nevertheless, fake news are spreading, alerting parents on dangerous side effects in children, such as hypercapnia, hypoxia, gut dysbiosis and immune system weakness. Aim of the Italian Pediatric Society statement is to face misconception towards the use of face masks and to spread scientific trustable information.

Pneumococcal conjugate vaccines: proceedings from an Interactive Symposium at the 41st Interscience Conference on Antimicrobial Agents and Chemothera…

2003

Globally, Streptococcus pneumoniae is a leading cause of invasive and noninvasive disease in infants and young children. The emergence of antibiotic-resistant strains has increased interest in prevention through immunization. Currently, the only available conjugate pneumococcal vaccine is a seven-valent formulation, PNCRM7. This paper presents excerpts from a symposium that provided an update of ongoing surveillance data and clinical trials evaluating pneumococcal conjugate vaccines. The topics addressed included: (1) PNCRM7 postmarketing safety data; (2) the impact of PNCRM7 in premature infants; (3) the direct and indirect effect of pneumococcal conjugate vaccines on colonization; (4) the…

Fever in pregnancy and congenital anomalies.

1979

Definition of criteria and indicators for the prevention of Healthcare-Associated Infections (HAIs) in hospitals for the purposes of Italian institut…

2017

Background. Healthcare-associated infections (HAIs) are an important issue in terms of quality of care. HAIs impact patient safety by contributing to higher rates of preventable mortality and prolonged hospita- lizations. In Italy, analysis of the currently available accreditation systems shows a substantial heteroge- neity of approaches for the prevention and surveillance of HAIs in hospitals. The aim of the present study is to develop and propose the use of a synthetic assessment tool that could be implemented homogenously throughout the nation. Methods. An analysis of nine international and of the 21 Italian regional accreditation systems was conducted in order to identify requirements a…

Novel path to apoptosis: small transmembrane pores created by staphylococcal alpha-toxin in T lymphocytes evoke internucleosomal DNA degradation.

1994

Peripheral-blood human T lymphocytes were treated with Staphylococcus aureus alpha-toxin. Membrane permeabilization was assessed by measuring efflux of K+ and Rb+ and influx of Na+, Ca2+, and propidium iodide. Cellular ATP and [3H]thymidine incorporation following lectin stimulation were measured as parameters for cell viability. Internucleosomal cleavage characteristic of programmed cell death was assessed by agarose gel electrophoresis and by quantifying low-molecular-weight, [3H]thymidine-labeled DNA fragments. Nanomolar concentrations of alpha-toxin evoked protracted, irreversible ATP depletion in both activated and resting T lymphocytes. Toxin-damaged cells also lost their ability to i…

Cytocidal effects of Escherichia coli hemolysin on human T lymphocytes.

1993

Escherichia coli hemolysin is the prototype of a large family of pore-forming toxins produced by gram-negative organisms. Besides its known cytotoxic activities against granulocytes, monocytes, endothelial cells, and renal epithelial cells, we now demonstrate that the toxin potently kills human T lymphocytes. Evidence based on different and independent approaches indicates that lymphocidal activity is due to formation of transmembrane pores. Additionally, cells prestimulated with phytohemagglutinin respond to low doses of E. coli hemolysin with DNA fragmentation similar to that observed in cells undergoing programmed cell death. Kinetic considerations lead us to conclude that DNA degradatio…

Caspase-dependent apoptosis during infection with Cryptosporidium parvum

1999

The protozoan parasite Cryptosporidium parvum causes persistent diarrhea and malnutrition in children and the diarrhea-wasting syndrome in AIDS. No therapy exists for eliminating the parasite in the absence of a healthy immune response. Although it had been reported that infection of intestinal cell lines with C. parvum leads to host cell death, the mechanisms of cytolysis have not been characterized. We show here that infection with C. parvum leads to typical apoptotic nuclear condensation and DNA fragmentation in host cells. Both nuclear condensation and DNA fragmentation are inhibited by a caspase inhibitor, showing that caspases are involved in this type of apoptosis. Finally, blocking …

Interferons increase cell resistance to Staphylococcal alpha-toxin.

2007

ABSTRACTMany bacterial pathogens, includingStaphylococcus aureus, use a variety of pore-forming toxins as important virulence factors. Staphylococcal alpha-toxin, a prototype β-barrel pore-forming toxin, triggers the release of proinflammatory mediators and induces primarily necrotic death in susceptible cells. However, whether host factors released in response to staphylococcal infections may increase cell resistance to alpha-toxin is not known. Here we show that prior exposure to interferons (IFNs) prevents alpha-toxin-induced membrane permeabilization, the depletion of ATP, and cell death. Moreover, pretreatment with IFN-α decreases alpha-toxin-induced secretion of interleukin 1β (IL-1β)…

Hepatitis C Virus NS3/4A Protease Inhibitors.

2008

Chronic hepatitis C virus infection is a global problem worldwide due to the lack of an effective therapy (the current standard of care treatment is effective in about 40-50% of the cases), and the difficulties in developing a protective vaccine. Chronic infection progresses to end-stage liver disease and liver failure in a considerable number of infected individuals. Once liver function is compromised, the only reliable therapeutic intervention is liver transplantation. Unfortunately, re-infection of the graft is unavoidable, and a new chronic hepatitis is early established in transplant recipients, that can result in graft loss. Thus, there is an urgent need for new, specifically targeted…