Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành y đề tài: Molecular mechanisms of autoimmunity triggered by microbial infection...
Harrison's Internal Medicine Chapter 132. Infections Caused by Listeria monocytogenes
Infections Caused by Listeria monocytogenes: Introduction
Listeria monocytogenes is a food-borne pathogen that can cause serious infections, particularly in pregnant women and immunocompromised individuals. A ubiquitous saprophytic environmental bacterium, L. monocytogenes is also a pathogen with a broad host range. Humans are probably accidental hosts for this microorganism. L.
Harrison's Internal Medicine Chapter 114. Molecular Mechanisms of Microbial Pathogenesis
Molecular Mechanisms of Microbial Pathogenesis: Introduction
Over the past three decades, molecular studies of the pathogenesis of microorganisms have yielded an explosion of information about the various microbial and host molecules that contribute to the processes of infection and disease.
Numerous virus–target cell interactions have been described, and it is now clear that different viruses can use similar host-cell receptors for entry. The list of certain and likely host receptors for viral pathogens is long. Among the host membrane components that can serve as receptors for viruses are sialic acids, gangliosides, glycosaminoglycans, integrins and other members of the immunoglobulin superfamily, histocompatibility antigens, and regulators and receptors for complement components.
Encounters with Epithelial Cells
Over the past decade, many bacterial pathogens have been shown to enter epithelial cells (Fig. 114-2); the bacteria often use specialized surface structures that bind to receptors, with consequent internalization. However, the exact role and the importance of this process in infection and disease are not well defined for most of these pathogens. Bacterial entry into host epithelial cells is seen as a means for dissemination to adjacent or deeper tissues or as a route to sanctuary to avoid ingestion and killing by professional phagocytes.
Encounters with Phagocytes
Phagocytosis and Inflammation Phagocytosis of microbes is a major innate host defense that limits the growth and spread of pathogens. Phagocytes appear rapidly at sites of infection in conjunction with the initiation of inflammation. Ingestion of microbes by both tissue-fixed macrophages and migrating phagocytes probably accounts for the limited ability of most microbial agents to cause disease.
Transmission to New Hosts
As part of the pathogenic process, most microbes are shed from the host, often in a form infectious for susceptible individuals. However, the rate of transmissibility may not necessarily be high, even if the disease is severe in the infected individual, as transmissibility and virulence are not linked traits.
Prosthetic valve endocarditis arising within 2 months of valve surgery is generally the result of intraoperative contamination of the prosthesis or a bacteremic postoperative complication. The nosocomial nature of these infections is reflected in their primary microbial causes: coagulase-negative staphylococci (CoNS), S. aureus, facultative gram-negative bacilli, diphtheroids, and fungi. The portals of entry and organisms causing cases beginning 12 months after surgery are similar to those in community-acquired native valve endocarditis.
Its central theme was derived from a comprehensive essay entitled “Infectious History” that he published several years earlier in Science (Lederberg, 2000; reprinted as Appendix WO-1). Under the heading, “Evolving Metaphors of Infection: Teach War No More,” Lederberg argued that “[w]e should think of each host and its parasites as a superorganism with the respective genomes yoked into a chimera of sorts.”
Nonimmunologic Mechanisms Nonimmunologic mechanisms that protect against pneumonia include filtration of air as it passes through the nasopharynx, the glottal reflex, laryngeal closure, the cough reflex, clearance of organisms from the lower airways by ciliated cells, and ingestion by pulmonary macrophages and PMNs of small bacterial inocula that manage to reach alveolar spaces. Respiratory virus infection, chronic pulmonary disease, or heart failure compromises these mechanisms, predisposing to the development of pneumococcal pneumonia.
Acute Sinusitis Just as the pathogenesis and microbial etiology of acute rhinosinusitis are similar to those of otitis media, so are the principles of diagnosis and treatment. The diagnosis is often empirical, and the less rigorously it is made, the more irrelevant antibiotics are likely to be.
This comprehensive volume covers the major viral, bacterial and fungal diseases in fi n- and
shellfi shes. It completes the three-volume series on fi sh diseases and disorders; Volume I
(published in 1995) is on parasitic diseases in fi n- and shellfi shes while Volume II (published
in 1998) deals with non-infectious disorders in fi nfi sh. Reviews in the three volumes
are written by international authorities that are actively working in the area or have contributed
greatly to our understanding of specifi c piscine diseases or disorders.
The book Cell Interaction focuses on various processes that occur within and outside the cells. Cell interactions are important for functioning of many organ systems: cell adhesion, tissue development, cellular communication, inflammation, tumor metastasis, and microbial infection. Key features include developmental cell interactions, immune and neural cell interactions, cell interactions in normal and disease conditions and advanced level methods to evaluate cell interactions.
Resistance towards the responsible pathogens are also seen in developed countries. The
situation has worsened often due to limited resource available to investigate and provide
reliable susceptibility data on which rational treatments can be based as well as means to
optimize the use of antimicrobial agents. The emergence of multi-drug-resistant isolates in
tuberculosis, acute respiratory infections and diarrhea, often referred to as diseases of
poverty, has had its greatest toll in developing countries.
Malaria, caused by four species of Plasmodium, of which Plasmodium falciparum is the most
dangerous, remains the world's most devastating human parasitic infection. This chapter deals with
the properties and uses of important drugs used to treat and prevent this infection. Highly effective
agents that act against asexual erythrocytic stages of malarial parasites responsible for clinical
attacks include chloroquine, quinine, quinidine, mefloquine, atovaquone, and the artemisinin
The AIDS epidemic has resoundingly illustrated this principle: the immunodeficiency of many HIV-infected patients permits the development of life-threatening fungal infections of the lung, blood, and brain. Other than the capsule of C. neoformans, specific fungal antigens involved in tissue invasion are not well characterized. Both fungal and protozoal pathogens undergo morphologic changes to spread within a host. Yeast-cell forms of C. albicans transform into hyphal forms when invading deeper tissues.
Listeria monocytogenes is a food-borne pathogen that can cause serious infections, particularly in pregnant women and immunocompromised individuals. A ubiquitous saprophytic environmental bacterium, L. monocytogenes is also a pathogen with a broad host range. Humans are probably accidental hosts for this microorganism. L. monocytogenes is of interest not only to clinicians but also to basic scientists as a model intracellular pathogen that is used to study basic mechanisms of microbial pathogenesis and host immunity. ...
Maliciously modiﬁed devices are already a reality. In
2006, Apple shipped iPods infected with the RavMonE
virus . During the cold war, the CIA sabotaged oil
pipeline control software, which was then allowed to
be “stolen” by Russian spies . Conversely, Russian
agents intercepted and modiﬁed typewriters which were
to be used at the US embassy in Moscow; the modiﬁca-
tions allowed the Russians to copy any documents typed
on said typewriters .
This book is an introduction to the exciting new
field of ecological genomics, for use in MSc courses
and by those beginning their PhD studies.
When we became involved in a national research
programme on ecological genomics, or ecogenomics
as it became known, we realized that information
on this newly emerging subject needed to be
brought together. In order to start up a research
programme in such a new discipline, not only the
students, but also we as teachers, had to get to grips
with the subject.
Over the past three decades, molecular studies of the pathogenesis of microorganisms have yielded an explosion of information about the various microbial and host molecules that contribute to the processes of infection and disease. These processes can be classified into several stages: microbial encounter with and entry into the host; microbial growth after entry; avoidance of innate host defenses; tissue invasion and tropism; tissue damage; and transmission to new hosts.